Pistons and Rings

updated 2019-12

Contents:

1. Piston Rings  2. Ring Info
3. Pistons Ring  4. Piston Info

 


1. Piston Rings

 

Listed as: D x h x w xxx Listed as: D x h1/h2 x w xxx Listed as: D x h1/h2 x w1/w2 xxx Listed as: N or  I xxxxxxxxxxx

GN gap (aka FG)
pin on side of groove

 

Meanings:
D
is the cylinder diameter that the ring would have a 0.004 to 0.008″ gap in
height is the thickness up-and-down. T & L rings have 2 heights, outer & inner
width is the depth inward-and-out. L rings have two widths, outer and inner
type C = Common “square”  shape (cross-section)
type T = Trapezoidal “slant top” shape (cross-section)
type L = L-shape  aka  “Dykes”  shape (cross-section)

GI gap style
pin inside groove

gap GN Grano Normale gap style is for ring pin on side of ring groove
gap GI  Grano Interno = gap style is for ring pin in center of ring groove
gap (blank) is for L-ring gap style, ring is like a GI but groove is like a GN
price is for each ring, unless noted.  All rings are for 50cc engines, unless noted.

                           R I N G S

0  size x height x width  type gap price     part number  applications
36.50
 x 1.50 1./x 1.7/0.7  C  N  $10.0 0 0000  222812 Tomos MC36 36cc
38.00 x 1.50 1./x 1.7/0.7  C   I   $10.0 0 0215.100.100 Sachs 1979-on 504,505 1C,1D upper
38.00 x 1.50 1./x 1.7/0.7  C  N  cont..  00.. 000000000 Zanetti (front engine)
38.00 x 1.5/1.3 x 1.60 /7  T  N  $17.0 0..0000 223707 Tomos A55 (2001-06) superseded in ’07 to 236802
38.00 x 1.50 1./x 1.7/0.7  C  N  $$9.0 0..0000 236802 Tomos A35 (1991-06), Tomos A55 (2007-on)
38.00 x 1.50 1./x 1.7/0.7  C  N  cont..  0 000.672.5110 Derbi 1976-1986 lower only, Odyssey, Solo
38.00 x 2.0/1.0 x 1.5/0.5  L  N  $10.0 0 000.802.5110 Derbi 1976-1986 upper (fits Puch loose inner)
38.00 x 2.0/1.0 x 1.7/0.7  L  N  $21.0 0 328.110.9601 Puch 1979-1980 deluxe models upper
38.00 x 2.00 1./x 1.7/0.7  $13.0 0 331.110.1601 Puch rounded edge for aluminum cylinder
38.00 x 2.00 1./x 1.7/0.7  $$9.0 0 320.110.0601 Puch except some ’79-80 upper
38.00 x 2.00 1./x 1.7/0.7  C  N  cont..  0 0215.009.000 Sachs 504, 505 1A,1B both, 1C,1D lower
38.00 x 2.00 1./x 1.7/0.7  C  N  cont..  0..0000 044754 Tomos A3 1975-1990, AMF BHE900 rear engine
38.00 x 2.00 1./x 1.7/0.7  C  N  cont..  00.000 26.1001 Morini S5K, S5K2, 2M, 3M, F48
38.00 x 2.50 x 1.50.7/0.7  C  N  $11.0 71.0802.0 4600 Minarelli V1 1hp 20mph, Sears Allstate, early Puch
38.00 x 2.50 1./x 1.7/0.7  C flat  N/A     0.00000000000 Solex 45cc 1946-1954  use 38.00 x 2.50 C N
38.20 x 1.50 1./x 1.7/0.7  C  N  $10.0 0..0000 182518 Piaggio 79-later & some 78s lower ring
38.20 x 2.00 1./x 1.7/0.7  C  N  $16.0 00..000 166945 Piaggio 78-80 USA-type, must file down a 077775
38.00 x 2.00 1./x 1.7/0.7  C  N  cont..  0000.0 26.1002 1os Morini S5K, S5K2, 2M, 3M, F48
38.20 x 2.0/1.0 x 1.8/.75  L  N  $14.0 0..0 000182519 Piaggio 79-later & some 78s upper ring
38.20 x 2.50 x 1.50.7/0.7  C  N  none.. 71.0852.7 4610 Minarelli 1os V1 1hp 20mph, Sears Allstate, early Puch
38.25 x 2.0/1.0 x 1.5/0.5  L  N  $11.0 000.802.5110 1os Derbi 1976-1986 upper ring
38.25 x 1.50 1./x 1.7/0.7  C  N  $15.0 0 000.672.2511 1os Derbi lower
38.40 x 1.50 1./x 1.7/0.7  C  N  $14.0 00 000  132515 std or 1os Piaggio lower ring, 79-later & some 78s
38.40 x 1.5/1.3 x 1.60 /7  T  N   N/A    0 000   3010010 Kinetic TFR (Vespa Si remake) 95-later
38.40 x 2.00 1./x 1.7/0.7  C  N  $12.0 0 0000  077775 Piaggio 77-earlier & some 78s, early Kinetic
38.40 x 2.0/1.0 x 1.8/.75  L  N  none.. 0 000   G.68473 std or 1os Piaggio upper ring, 79-later & some 78s
38.40 x 2.50 x 1.50.7/0.7  C  N  $9.00 71.0852.7 4620 Minarelli 2os V1 1hp 20mph, Sears Allstate, early Puch
38.50 x 1.50 1./x 1.7/0.7  C  N  $12.0 0 0000  227758 1os Tomos A35
38.50 x 2.00 1./x 1.7/0.7  C  N  $10.0 0 0000  044751 1os Tomos A3
38.60 x 1.50 1./x 1.7/0.7  C  N  $9.00 000000 137693 1os or 2os Piaggio  
38.60 x 2.00 1./x 1.7/0.7  C  N  $14.0 0 00000  98196 1os Sachs 504, 505, 2os Piaggio 79- lower
38.60 x 2.0/1.0 x 1.8/.75  L  N  $13.0 0 00000 137690 1os or 2os Piaggio upper ring, 79-later & some 78s
38.70 x 1.50 1./x 1.7/0.7  C  N  $16.0 71.0803.0 4635 Minarelli V1 (US 1979-on and some ’78)
38.80 x 2.0/1.0 x 1.65/.6  L  N  $11.0  4.7470.5140 Demm Smily upper
38.80 x 1.50 x 1.50.7/0.7  C  N  cont..  0000 68.0116.0 Minarelli P4 (export al-cyl, Compact System, Radiale) upper
38.80 x 2.0/1.0 x 1.8/.75  L  N  $11.0  000000
137691 2os Piaggio upper ring
38.80 x 1.50 x 1.50.7/0.7  C  N  $10.0 71.0805.0 4640 Minarelli V1 (US to-1978)
38.80 x 1.50 x 1.50.7/0.7  C  N  cont..  0000 68.0115.0 Minarelli P4 (export iron-cyl, Sport Quadro) both
38.80 x 1.50 x 1.50.7/0.7  C  N  cont.. 
0000
68.0115.0 Minarelli P4 (export al-cyl, Compact System, Radiale) lower
38.80 x 1.50 x 1.50.7/0.7  C  N 
cont..  00.00   137694 2os Piaggio upper ring
38.80 x 1.50 1./x 1.7/0.7  C   I   N/A 00000   22350-65 Aermacchi Harley Davidson M50 1965-66 stroke 42
38.80 x 2.00 1./x 1.7/0.7  C  N  $10.0 00 4.7470.5100 Demm Smily lower
39.00 x 1.00 1./x 1.7/0.7  C  N  $19.0 0.000   26.1060 Morini S5N, S5GS kids off road, both
39.00 x 1.2/1.0 x 1.70 /7  T   I    N/A
   13011.GE2.305a Honda NS50 upper
39.00 x 1.20 x 1.85 /0..7  C   I   $10.0
13011.GE2.305b Honda NS50 lower
39.00 x 1.50 1./x 1.7/0.7  C  N  $10.0 71.0855.7 4650 1os Minarelli  V1, P4, P4 (alum cyl) lower
39.00 x 1.50 1./x 1.7/0.7  C  N  cont..   00.00  26.1044 Morini S5R, S5T, S5E, S5ET kids off road, lower
39.00 x 1.50 1./x 1.7/0.7  C   I   $10.0 0000 22351-65 1os Aermacchi Harley Davidson M50 1965-66
39.00 x 2.00 1./x 1.7/0.7  C   I   $12.0 000000   22148 Motobecane (GI after June 1976)
39.00 x 2.00 1./x 1.7/0.7  C  N  $10.0 000000   22148 Motobecane (FG before July 1975), DiBlasi mini-cycle
39.00 x 2.0/1.0 x 1.8/0.7  L  N  $11.0   00000 26.1003 Morini S5R, S5T alum. cylinder (upper ring)
39.03 x 2.00 1./x 1.7/0.7  C   I   $14.0 00 00  2812200 Jawa 207 1970-83 standard
39.20 x 1.50 1./x 1.7/0.7  C  N  $15.0 71.0855.7 4660 2os Minarelli V1, P4, P4 (al-cyl) lower
39.20 x 1.50 1./x 1.7/0.7  C   I   N/A    00000 22352-65 2os Aermacchi Harley Davidson M50 1965-66
39.25 x 1.2/1.0 x 1.70 /7  T   I   $19.013012.GE2.305a 1os Honda NS50 upper
39.25 x 1.20 x 1.85 /0..7  C   I   $10.0
13012.GE2.305b1os Honda NS50 lower
39.28 x 2.00 x 1.65 /0..7  C   I   $14.0 00 00  2812201 1os Jawa 207 1970-83
39.40 x 1.50 1./x 1.7/0.7  N   N/A    71.0855.7 4670 3os Minarelli V1, P4, P4 (al-cyl) lower
39.40 x 1.50 1./x 1.7/0.7  C   I   N/A   00000 22353-65 3os Aermacchi Harley Davidson M50 1965-66
39.40 x 2.50 1./x 1.7/0.7  C  N   N/A    000 0  0000000 Rizzato Califfo 1978 (Rizzato 119 engine)
39.50 x 1.2/1.0 x 1.70 /7  T   I    N/A   13013.GE2.305a 2os Honda NS50 upper
39.50 x 1.20 x 1.85 /0..7  C   I   $10.013013.GE2.305b 2os Honda NS50 lower
39.50 x 1.70 x 1.60 /0..7  C flat $10.0 00 0000  60817 Solex rings (3) no locating pins
39.53 x 2.00 x 1.65 /0..7  C   I   $19.0 00 00  2812202 2os Jawa 207 1970-83
39.60 x 1.50 1./x 1.7/0.7  C  N  $17.0 71.0855.7 4680 4os Minarelli  V1, P4, P4 (al-cyl) lower
39.80 x 1.50 1./x 1.7/0.7  C  N  $17.0 71.0855.7 4690 5os Minarelli V1, P4, P4 (al-cyl) lower
39.80 x 2.50 1./x 1.7/0.7  C  N 
$10    000 0  0000000 1os Rizzato Califfo 1978 (Rizzato 119 engine)
40.00 x 1.2/1.0 x 1.60 /7  T  N  $14.0 000 00  633086 China 49cc two-strokes upper, most
40.00 x 1.2/1.0 x 1.70 /7  T   I   $14 2W1.11610.0000a Yamaha YSR50 upper, PGO Star 50 upper, others
40.00 x 1.20 x 1.85 /0..7  C   I   $13 2W1.11610.0000b Yamaha YSR50 lower, PGO Star 50 lower, others
40.00 x 1.5/1.3 x 1.80 /7 
$14.0 13011.147.005a Dailim Trac, upper for Honda NC50,PA50,Yamaha QT50
40.00 x 1.50 1./x 1.7/0.7  C  N  $10.0 00 0000  55196 Batavus M48, M56, Trac (not Daelim), Flandria 
Bermuda
40.00 x 1.50 1./x 1.7/0.7  C  N 
cont..  13011.147.005b Honda lower for NC50,PA50, Yamaha QT50 lower
40.00 x 1.50 1./x 1.7/0.7  C  N 
cont..  000000   G7347 Benelli G2, 1965-75 Ward Riverside, Benelli mini-cycles
40.00 x 1.50 1./x 1.7/0.7  C  N 
cont..  00000  26.1044 Morini S5R, S5T alum. cylinder (lower ring)
40.00 x 1.50 1./x 1.7/0.7  C   I   $10.0  00000  551913 Morini MO Gyromat,Convert (early ’70s MO1,MO2)
40.00 x 1.50 1./x 1.7/0.7  C   I 
cont..     0F0.250.0111 Derbi 1986-1989 flat reed, Kreidler Flory
40.00 x 2.00 1./x 1.7/0.7  C  N  $10.0 00   307.021.00 Garelli all 1970’s, 00’s Avanti/Mont (most)
40.00 x 2.00 1./x 1.7/0.7  C  N cont..   00   307.021.00 Casal K177, 2000’s Hero Majestic Pacer
40.00 x 2.0/1.0 x 1.8/0.7  L  N   $11.0 0 310.001.00 Garelli Monza GT upper

40.00 x 2.50 1./x 1.7/0.7  C   I   $15.0 0000000  38315 Peugeot 102, 103 (almost all US models)
40.20 x 1.50 1./x 1.7/0.7  C  N  $22.0 0000   G7347/2 1os Benelli, 1os M Ward, filed down 40.25
40.20 x 2.00 1./x 1.7/0.7  C  N  $15.0 00   308.027.00 1os Garelli
40.25 x 1.00 1./x 1.7/0.7  C  N  $12.0 000..00 633087 1os China 49cc two-stroke scooter
40.25 x 1.5/1.3 x 1.80 /7  T  N   N/A    13021.147.005a 1os Honda NC50, PA50 upper
40.25 x 1.50 1./x 1.7/0.7  C  N  $15.013021.147.005b 1os Honda NC50, PA50 lower, 480511 1os Laura M48
40.30 x 1.50 1./x 1.7/0.7  C  N  $19.0 000000   4641b Minarelli V1HL and V1L lower, filed down 40.5
40.30 x 2.0/1.0 x 1.8/0.7  L  N   
N/A    000000   4641a Minarelli V1L upper
40.40 x 1.50 1./x 1.7/0.7  C  N   N/A    0000   G7347/4 2os Benelli  G2, 2os M Ward and mini-cycles
40.40 x 1.50 1./x 1.7/0.7   I   $$9.0 00 00   26.1045 Morini MO1, MO2, MO4, M1

40.40 x 2.00 1./x 1.7/0.7  C  N  $12.0 0 0  308.028.00 2os Garelli
40.50 x 1.5/1.3 x 1.80 /7  T  N   N/A   13031.147.005a 2os Honda NC50, PA50 upper
40.50 x 1.50 1./x 1.7/0.7  C  N  $12.013031.147.005b 2os Honda NC50, PA50 lower, 2os Laura M48
40.50 x 2.50 1./x 1.7/0.7   I   $12.0 00 0000  33648 1os Peugeot 102, 103 (some, but none in CA)
40.60 x 1.50 1./x 1.7/0.7  C  N  $16.0 00000 G7347/6 3os Benelli, 3os M Ward
40.60 x 1.50 1./x 1.7/0.7  C  N  cont..   71.0860.7 4651b 1os Minarelli V1L lower
40.60 x 1.50 1./x 1.7/0.7  C   I  $12.0 0000 26.1046/6 1os Morini MO1, MO2, MO4, M1
40.60 x 2.00 1./x 1.7/0.7  C  N  $10.0 0 0  308.029.00 3os Garelli
40.60 x 2.0/1.0 x 1.65/.6  L  N  $15.071.0860.7 4651a 1os Minarelli V1L upper
40.75 x 1.5/1.3 x 1.80 /7  T  N   N/A    13041.147.005a 3os Honda NC50, PA50 upper
40.75 x 1.50 1./x 1.7/0.7  C  N   N/A    13041.147.005b 3os Honda NC50, PA50 lower
40.80 x 1.50 1./x 1.7/0.7  C   I   $12.0 000   26.1046/8 2os Morini MO1, MO2, MO4, M1
40.80 x 1.50 1./x 1.7/0.7  C  N  $9.0 71.0860.7 4661b 2os Minarelli V1L lower
40.80 x 2.0/1.0 x 1.65/.6  L  N   N/A   71.0860.7 4661a 2os Minarelli V1L upper

40.80 x 2.00 1./x 1.7/0.7  C  N  $10.0  00  308.030.00 4os Garelli 

41.00 x 1.2/1.0 x 1.90 /7  T   I   
$14   
13010.GJ5.015a Honda TG50, NN50 Gyro upper
41.00 x 1.2/1.0 x 1.90 /7  C   I   N/A    13010.GJ5.015b Honda TG50, NN50 Gyro lower
41.00 x 1.5/1.3 x 1.80 /7  T   I   $14.0 0  12140-16B10 Suzuki FY50, FZ50, FA50 upper
41.00 x 1.50 1./x 1.7/0.7  C  N  $10.0 0000000  00000 Minarelli V1 Industriale 53cc stroke 42

41.40 x 1.50 1./x 1.7/0.7  C   I   $12.0 0000000  00000 Unknown only one
42.00 x 1.50 1./x 1.7/0.7  C  N   N/A    0 00000  00000 Minarelli V1 Carabela 58cc stroke 42
42.00 x 2.00 1./x 1.7/0.7  C  N  $12.0 0000000  00000 Unknown only two
42.00 x 1.50 1./x 1.7/0.7  C flat
$40/set    E660-00-50 Indian 4-stroke ring set comp(2) oil(1)
42.25 x 1.50 1./x 1.7/0.7  C flat
$40/set    E660-10-50 1os Indian 4-stroke set comp(2) oil(1)
42.50 x 1.50 1./x 1.7/0.7  C flat  N/A     
     E660-20-50 2os Indian 4-stroke set comp(2) oil(1)
42.75 x 1.50 1./x 1.7/0.7  C  N  $12.0 0000000  00000 big bore kit appr 60cc only two
43.00 x 1.50 1./x 1.7/0.7  C  N  $12.0 0000000  00000 big bore kit appr 60cc only one
43.00 x 2.0/1.0 x 1.65/.6  L   N  $16.0 0000000  00000 big bore kit appr 60cc only one
43.50 x 1.50 1./x 1.7/0.7  C  N  $10.0 0000000  00000 big bore kit appr 60cc

44.00 x 1.50 1./x 1.7/0.7  C  N  $10.0 0000000  G-591 Benelli Dynamo 65 59cc stroke 39
44.00 x 1.50 1./x 1.7/0.7  C  N 
cont..  00000    MF-554 big bore kit Peugeot 103 59cc
44.00 x 1.50 1./x 1.7/0.7  C   I    N/A    00000 22350-67 Aermacchi Harley Davidson M65 1967-72 64cc stroke 42
44.20 x 1.50 1./x 1.7/0.7  C   I    N/A    00000 22351-67 1os Aermacchi Harley Davidson M65 1967-72 64.5
44.40 x 1.50 1./x 1.7/0.7  C   I    N/A    00000 22352-67 2os Aermacchi Harley Davidson M65 1967-72 65cc

45.00 x 1.50 1./x 1.7/0.7  C  N   N/A    0 0000. 71.8187 Minarelli P4-70, P6-70 67cc
45.20 x 1.50 1./x 1.7/0.7  C  N   N/A    0 0000. 71.8187 1os Minarelli P4-70, P6-70 67cc
45.40 x 1.50 1./x 1.7/0.7  C  N   N/A    0 0000. 71.8187 2os Minarelli P4-70, P6-70 67cc  

 

 


2. Ring Information

 

Pinned or Not Pinned: Most moped piston rings are two-stroke style, where there are pins in the ring grooves of the piston that keep the rings from rotating around. Two stroke cylinders have holes or ports that the ring ends can snag on. So two stroke rings are pinned to the piston. Four stroke cylinders do not have any holes, so four stroke rings are not pinned. Knowing about those pins is important when installing.    

Getting the right rings: If your model is not in the applications, then you must measure the bore and the ring thickness. A calipers is the best tool to measure the bore (ring diameter) and ring thickness. Sometimes your rings might not be original, for many reasons. The piston might be aftermarket with thinner rings. The cylinder might be bored out to an oversize bore. Some mopeds came with more than one piston size or ring style.

Break a ring, how not to: Two stroke pistons have little pins (stumps, bumps) in the piston ring grooves that prevent the rings from rotating. Knowing where each ring locating pin is, and aligning the ring gap over the pin during cylinder installation, is the key to not breaking the ring. 

Measuring wear: A new piston ring is a the best tool to measure how worn a cylinder is. Conversely, a new cylinder is the best tool to measure how worn a ring is. To measure the wear of a ring, you need a perfectly round cylinder of a precisely known bore. A worn cylinder that has not been honed will still have it’s original new bore at the very top, above where the rings rub at. A new ring in a new cylinder should have a very small end gap of .004 to .008″. A worn but still OK cylinder with a new ring will have a gap of .0010 to .018″. A worn cylinder and ring both will have an end gap of over .020″(.5mm). A badly worn cylinder and/or ring will have a huge gap, over .030″(.75mm). You measure ring gap with a feeler gauge.

Classifying Jawa Rings

Classifying Piston Rings

Classifying rings: Rings get mixed up and are difficult to tell the size, unless a perfectly round cylinder of an appropriate size is available to place the ring in. If you try to squeeze a piston ring into a circle with just fingers, it inevitably becomes a very rounded polygon, or at best an ellipse. So the measurement becomes inaccurate. At right is how Myrons Mopeds’s Jawa piston rings were classified, using a piece of aluminum tubing with a tight fitting piston inside it to hold the tube round, and the test ring square. From top to bottom, 39.03 x 2.0, 39.28 x 2.0, 39.53 x 2.0, 39.78 x 2.0mm. Each ring increases in diameter by 0.25mm, so the circumference increases by Pi times that, or about 0.8mm. Here the inside of an old fishing pole tube is 39.78mm, perfect for the 3rd oversize 39.78 ring, on the bottom, with a gap of almost zero. Each gap is 0.8mm more because each ring is 0.25mm less diameter. It is important that the piston and ring fit the cylinder properly.   

Filing down: To make a ring slightly smaller, one of the two ring ends can be filed down, while preserving the shape. To reduce the size (diameter) by 0.20 mm, the end must be filed down by pi times that, 0.63 mm. When a filed down ring is installed in a cylinder smaller than it was designed for, two things change. The tension is greater, and the shape is slightly non-circular. So filed rings need a longer break-in period, to wear down the higher places. With 38 to 41 mm rings, the size can be reduced by 0.2mm with about 30 minutes of break-in, and by 0.5mm with about 2 hours of break-in. After break-in the rings have a mirror polish all around.

Why is the width not specified? Because the inner side of the ring does not touch anything. The ring has spring tension pushing it outwards, keeping the bottom (inner) surface from touching the bottom of the ring groove. So the ring width can be any amount, from about half the groove depth, to the groove depth. The exact ring width is not important. Exact ring height and diameter are important. 

 

 


3. Pistons

 


50cc pistons for sale here are listed by “pin”, the wrist pin thickness, and “upper”, the distance from the pin edge to the top edge. Pin ranges from 10 to 14mm. Upper ranges from 13 to 23mm.

Pistons in the same section have the same upper and pin dimensions, and so can potentially interchange, if the bore and maybe other things are the same. That is why pistons are listed by size rather than name.

For example, an oversize Peugeot 103 piston 40.5mm is perfect for a worn 40.4mm Morini MO1, after honing. They are both 12 pin and 16 upper, in the 12-16 section.

Alphabetical Name Index of Section Numbers
12-18
Batavus with Laura M48 engine
12-17 Benelli 1965-1980
12-23 Casal K177, others
10-19 Columbia with Solo 255 engine
12-22 Columbia with Sachs 505 engine

12-18 Daelim DP50, DK50 engine
12-22 Demm Smily

12-17 Derbi Variant, TT, RD50 1974-1986
12-18 Derbi Variant Sport 1986-90
14-24 Flandria Bermuda
12-18 Garelli Eureka, Noi, Gulp, VIP
12-22 Garelli Monza GT

12-16 Hero Majestic mid-90’s
10-20 Honda NC50, NA50, NU50, PA50
12-19 Honda NS50F
13-13 Indian AMI50 with PC50K1 re-make engine
14-18 Jawa Babetta 207 1970-83
12-16 Kawasaki AR50

12-20 Kinetic TFR with Piaggio re-make engine
12-19 Kreidler MP9, MP19
12-18 Laura M48, M56 engine

12-21 Minarelli V1L, V1HL engine
12-22 Minarelli V1, V1H engine
12-16 Morini MO1, MO2, MO4, M1, M101 engine
12-22 Morini S5K, S5K2, S5R, S5T engine
13-15 Motobecane 40, 50 with AV7 engine
10-19 Odyssey with Solo 254, 255 engine

12-16 Peugeot 102, 103 series
10-18 Puch MS50, others 50’s-60’s
12-17 Puch Maxi, others 1969-86
12-15 Rizzato 119 engine on Califfo
12-22 Sachs 504, 505 engine
10-18 Sears Allstate moped and early Puch

10-19 Solo 236, 237, 254, 255 engine
12-21 Suzuki FA50 Shuttle, FY50, FZ50
10-18 Tomos A3 engine 1974-91
12-17 Tomos A35 engine 1992-2006 (cyl says A5)
12-17 Tomos A55 engine 2002-18 (case says A52)

12-18 Trac 1981-96 with M56-remake engine
10-19 TYM M48-remake engine on Angel, Speed Bird
12-20 Vespa (Piaggio) Ciao, Bravo, Grande, Si
10-21 Vespa (Piaggio) Ciao, Si (1990’s Euro)
10-20 Yamaha QT50 Yamahopper, PW50

 

Notes:
Piston actual diameter is measured at skirt (bottom), where it is largest. 
All new pistons come with new rings, clips and pin, unless noted.
gap GN grano normale means side pin gap style (aka FG foro grano)                        
gap GI  grano interno means center pin gap style  (see photos above)

Meanings:  “size” = cylinder bore                
ring c1.5n means common (rectangular), 1.5mm thick,  normal gap style
ring c1.5i  means common (rectangular), 1.5mm thick,  internal gap style
ring t1.5n means trapezoidal (slanted top) 1.5mm outer, normal gap style

ring t1.5i 
means trapezoidal (slanted top) 1.5mm outer, internal gap style
ring L1.5  means “L“-shaped (aka Dykes), 1.5mm outer, L-ring gap style
“x” means that part of the number is unknown

 


10-18  1974-91 Tomos A3, 50’s-60’s Puch and Tomos

000000  part#   lower  @skirt  ring1   ring2   maker  price    38.0 bore, 10 pin, 18 upper
0000002074??     24.0  37.94  c2.0n  c2.0n  Mahle    none  original  Tomos A3 1.0hp (55 total height, 52 at edge)
000000207407    21.0  37.94  c2.0n  c2.0n  Mahle    none  original  Tomos A3 1.5hp (52 total height, 49 at edge)
000000207403    19.0  37.94  c2.0n  c2.0n  Mahle    $50   original  Tomos A3 2.0hp (50 total height, 47 at edge)
000000207403a  19.0  37.95  c1.5n  c1.5n  generic  $60   re-make Tomos A3
000000206200    18.0  37.9x  c2.0n  c2.0n  generic  none  re-make Tomos A3
000501.1006.2    ????  37.9x  c2.5n  c2.5n  Mahle  none  original Sears Allstate
000000  part#   lower  @skirt  ring1   ring2   maker  price    38.5 bore, 10 pin, 18 upper
000000202420    19.0  38.45  c2.0n  c2.0n  Mahle    none  original  Tomos A3 oversize

Tomos A3 piston

Tomos A3

18mm upper, 10 pin, 1950s-60's Puch

50’s-60’s Puch

Solo Piston

Tomos and Solo

Angel and Batavus pistons

Angel and Batavus

 
 
 
 
 
 

 

 


10-19  1976-80 Solo on Odyssey,Columbia, ’77-84 TYM Angel 

000000  part#   lower  @skirt  ring1  ring2   maker  price    38.0 bore, 10 pin, 19 upper
0000002200593  22.0  37.9x  c1.5n  c1.5n  Mahle    none  original  Solo piston “N”
0000002200600  22.0  37.9x  c1.5n  c1.5n  Mahle    none  original  Solo piston “U”
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.0 bore, 10 pin, 19 upper
0000000000000  15.0  39.92  c1.5n  c1.5n  generic  none  original  Angel/Speed Bird

A Batavus piston (12 x 33 mm pin) can substitute for an Angel piston (10 x 33 pin), if the piston pin needle bearing is changed. The 10x14x13 needle bearing (with 2mm rollers) needs to be 12x14x13. But there are none that thin (1mm rollers). So a bronze bushing 12x14x13 must be used instead of a needle bearing, like one from a Puch.  There are already oil holes in the Angel rod. Those holes need to extend through the bronze bushing to oil the pin.


10-20 1977-83 Honda NC50 PA50, Yamaha QT50 PW50

000000  part#   lower  @skirt  ring1  ring2   maker  price    40.0 bore, 10 pin, 20.5 upper
13101.147.000    18.0  39.95  t1.5n  c1.5n  Honda   none   original  Honda NC50 and PA50 (has decomp cut)
13101.147.000a  18.0  39.95  t1.5n  c1.5n  generic  $43.0 re-make Honda NC50, PA50
3L5.11630.00.00 17.5  39.9x  t1.5n  c1.5n  Yamaha  none   original  Yamaha QT50 Yamahopper and PW50

20mm upper (10mm pin) Honda NC50

Honda NC50, PA50

Honda NC50 and PA50 piston new

Honda NC50

20mm upper (10mm pin) Yamaha QT50 & PW50

Yamaha QT50, PW50

21mm upper, 10 pin, Vespa Euro models

Vespa Euro

21mm upper, 10mm pin Chinese scooters

Eton scooter

 

 

 

 

 

 


10-21  1990’s Vespa (Euro), China scooters

000000  part#   lower  @skirt  ring1  ring2   maker  price    38.2 bore, 10 pin, 21 upper
000000000000   17.0  38.13  L2.0n  c1.5n  Meteor  $60  original  Vespa 84-85 Ciao & Si, Euro models
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.0 bore, 10 pin, 21 upper
000000632964   18.0  39.9x  t1.2n  t1.2n  generic  $60   re-make E-Ton 50cc 2-stroke scooter
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.25 bore, 10 pin, 21 upper
000000632965   18.0  40.1x  t1.2n  t1.2n  generic  $60   re-make 1os E-Ton 50cc 2-stroke scooter

 

Rizzato

12-15  Rizzato 119 engine on Califfo, Atala


000  part#   lower  @skirt  ring1  ring2   maker  price    39.4 bore, 12 pin, 15 upper
000
000000   23.0  39.32  c2.5n  c2.5n  generic  none  original  Rizzato Califfo (no rings)
000  part#   lower  @skirt  ring1  ring2   maker  price    39.8 bore, 12 pin, 15 upper
000
000000   23.0  39.72  c2.5n  c2.5n  generic $65.0 original  1os Rizzato Califfo

This is an unusual design from the 1950’s, with the highest wrist pin. That allows transfer flow through the lower part of the piston, instead of around the sides completely. The top crown of the piston is a normal shallow dome, but with three equal large “bites” taken out of it. More about this later…


12-16  Peugeot 103 102, Morini MO1 MO2 M1 M101, 90’s Hero

000000  part#   lower  @skirt  ring1  ring2   maker  price    39.0 bore, 12 pin, 16 upper
00013001.1074  18.0  38.95  t1.2n  t1.2n  generic   none  original  Kawasaki AR50
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.0 bore, 12 pin, 16 upper
000000069707   17.0  39.88  c2.5i   c2.5i  Peugeot  $70   original  Peugeot Sort A
000000069708   17.0  39.89  c2.5i   c2.5i  Peugeot  $70   original  Peugeot Sort B
000000069709   17.0  39.90  c2.5i   c2.5i  Peugeot  $70   original  Peugeot Sort C (=AA)
000000069710   17.0  39.91  c2.5i   c2.5i  Peugeot  none  original  Peugeot Sort D (=BB)
000000000000   17.0  39.92  c1.5i   c1.5i  Asso 00  none  original  Verona (like MO1), 3mm skirt cut
000000000000   17.0  39.9x  c2.0n  c2.0n generic   none  original  Hero Pacer, Panther
000000069711   17.0  39.92  c2.5i   c2.5i  Peugeot  $70   original  Peugeot Sort E (=CC) most common
000000069712   17.0  39.93  c2.5i   c2.5i  Peugeot  $70   original  Peugeot Sort F (=DD)
00000MF553-F   17.0  39.93  c1.5i   c2.5i  generic   $70   re-make MMI for Peugeot
000000069713   17.0  39.94  c2.5i   c2.5i  Peugeot  $70   original  Peugeot Sort G (=EE)
000000069714   17.0  39.95  c2.5i   c2.5i  Peugeot  $70   original  Peugeot Sort H (=FF)
00000MF553-C   17.0  39.95  c2.5i   c1.5i  generic   $70   re-make MMI for Peugeot
000000069715   17.0  39.96  c2.5i   c2.5i  Peugeot  none  original  Peugeot Sort I (=GG)
00000069715a   17.0  39.97  c2.5i   c2.5i  Peugeot  none  original  Peugeot Sort HH
00000069715b   17.0  39.98  c2.5i   c2.5i  Peugeot  none  original  Peugeot Sort II
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.4 bore, 12 pin, 16 upper
000000000000   17.0  40.33  L2.0n  c1.5i  Asso       none  original  Morini MO4, 3mm sk. cut ASSO 1929MO4
00000023.0125  17.0  40.31  c1.5I   c1.5i  generic   none  original  Morini MO1,2, 3mm skirt cut  says nothing
00000023.0125  17.0  40.32  c1.5I   c1.5i  Asso       none  original  Morini MO1,2, 3mm skirt cut ASSO.W 2352
00000023.0134  17.0  40.32  c1.5I   c1.5i  Asso       none  original  Morini M1, zero skirt cut,   ASSO W 1929M1
00000023.0134  17.0  40.32  c1.5I   c1.5i  Meteor  $60  generic  Morini M1, zero skirt cut,   
00000023.0125  17.0  40.32  c1.5I   c1.5i  Asso       none  original  Morini MO1,2, 3mm skirt cut   ASSO 1929
00000023.0125  17.0  40.35  c1.5I   c1.5i  Asso       $70   original  Morini MO1,2, 5mm skirt cut ASSO.W 2351
00000023.0136  17.0  40.3x  c1.5I   c1.5i  Asso       none  original  Morini M101 variator engine
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.5 bore, 12 pin, 16 upper
000000069716   17.0  40.44  c2.5i   c2.5i  Peugeot  $60   original  1os Peugeot oversize Sort K
000000069717   17.0  40.45  c2.5i   c2.5i  Peugeot  $60   original  1os Peugeot oversize Sort L
000000069718   17.0  40.46  c2.5i   c2.5i  Peugeot  $60   original  1os Peugeot oversize Sort M
000000069719   17.0  40.47  c2.5i   c2.5i  Peugeot  $60   original  1os Peugeot oversize Sort N
000000069720   17.0  40.48  c2.5i   c2.5i  Peugeot  $60   original  1os Peugeot oversize Sort P
000000069721   17.0  40.49  c2.5i   c2.5i  Peugeot  $60   original  1os Peugeot oversize Sort Q
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.6 bore, 12 pin, 16 upper
000023.0126/6   17.0  40.53  c1.5i   c1.5i   Asso     $70   original  1os Mor MO1,2, 3mm skirt cut ASSO 1929
000023.0135/6   17.0  40.5x  c1.5i   c1.5i  Asso      none  original  1os Mor M1, zero skirt cut ASSO W 1929M1
000023.0136/6   17.0  40.5x  c1.5i   c1.5i  Asso      none  original  1os Morini M101 variator engine
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.8 bore, 12 pin, 16 upper
000023.0126/8   17.0  40.72  c1.5i   c1.5i  Asso      $75   original  2os Mor MO1,2, 3mm skirt cut ASSO 1929
000023.0135/8   17.0  40.7x  c1.5i   c1.5i  Asso      none  original  2os Mor M1, zero skirt cut ASSO W 1929M1
000023.0136/8   17.0  40.7x  c1.5i   c1.5i  Asso      none  original  2os Morini M101 variator engine
000000  part#   lower  @skirt  ring1  ring2   maker  price    41.0 bore, 12 pin, 16 upper
000023.0126/0   17.0  40.90  c1.5i   c1.5i  generic  $70  original  3os Mor MO1,2, 3mm skirt cut  says nothing

16mm upper, 12 pin, Peugeot

Peugeot 103

16mm upper height pistons Peugeot left and Morini right

Peugeot and Morini

Morini Pistons Nov 2013

.

 

 

 

 

16mm upper, 12mm pin, Morini piston #230136

Morini M101

1995 Hero Panther

1995 Hero Panther

 

 

 

 

 

 

Morini made a variety of 50cc engines. These pistons shown here are only for 1960’s to 80’s moped-type engines Morini MO, MO1, MO2, M1, MO2 foot shift, MO4, all 40.4mm. They also fit Verona, early Gyromat, and Benelli mopeds, originally 40.0mm, as an oversize. All of the rings and ring pin locations are the same.

Peugeot 1980 tiny

Peugeot 103 pistons have slightly different sizes.

Peugeot 103 pistons have slightly different sizes, aka “sorts”.
Left of the red line are the “standard” 40.0mm sorts A to II (39.88-39.98).
Right of the red line are the “oversize” 40.5mm sorts K to Q (40.45-40.50).
Upper half are chrome bore cylinders, pre-1979 with single letter sorts A to Q.
Lower half are nikasil bore cylinders, 1979-on with double letter sorts AA to II.

Peugeot 103 moped pistons are a very old design that has been in use at least since the 1950’s. The rings are thick, 2.5mm, like most old rings were. Peugeot 103 cylinders are all aluminum with a chrome plated (pre-1979) or nikasil plated (1979-on) cylinder wall. They expand along with the aluminum piston as they get hotter. Unlike a steel sleeve cylinder that fits slightly loose, when cold, and wiggles a tiny bit, these should be a light sliding fit, where the piston, without rings, pushes through by hand but does not fall through by it’s own weight. When the piston fit is too loose, it makes a tinkle sound when idling, and produces less torque. When it’s too tight, it simply won’t move easy, or at all, and when hot it will smear (melt off) the hot exhaust side and stick (seize). The procedure for “fitting” a Peugeot piston requires a flat stone cylinder hone (not a ball hone) for first making the cylinder wall flat by removing any high spots, and a Dremmel high speed rotary cutting tool for removing burrs from the edges of the ports, and a small round file for removing burrs and high spots from the piston, especially around the wrist pin holes. Sometimes just the act of pushing the wrist pin in and out will raise the corner edge and make the piston fit tighter. The bare piston is pushed into the cylinder in different ways. The high spots are located, by feel and sometimes vision, and removed. When all high spots are removed, and the piston still does not fall through under it’s own weight, then the fit is perfect.  Worn cylinders need slightly bigger pistons. So a worn “C” cylinder might need a D, E, or F piston. Badly worn or “gouged” cylinders need to be replaced (unless the gouges are lower than the exhaust port). Peugeot has made plenty of “oversize” (40.5mm instead of 40.0mm) pistons. But there are no 40.5 cylinders in California, only 40.0mm. That’s why Myrons Mopeds has 40.5 pistons but no cylinders. Too bad it’s expensive to bore out and re-plate a nikasil cylinder. It is an option, made possible by the half millimeter bigger pistons available.

 


12-17  1969-86 Puch, 91-18 Tomos, 74-86 Derbi, 65-80 Benelli

000000  part#   lower  @skirt  ring1  ring2   maker  price    36.5 bore, 12 pin, 17 upper
000000229803    18.0  36.43  c1.5n  c1.5n  Vertex  $55   original  Tomos MC36 36cc kids dirt bike
000000  part#   lower  @skirt  ring1  ring2   maker  price    38.0 bore, 12 pin, 17 upper
000000406300    19.0  37.91  c2.0n  c2.0n  generic $30   re-make Puch early 2000’s, way too small
000000406300    18.0  37.93  c2.0n  c2.0n  generic $40   re-make Puch Step II, made small to fit all
0000000037A-C  23.0  37.94  c2.0n  c2.0n   GOL     $60   re-make Puch, made in Italy by GOL
0000000037A-D  23.0  37.95  c2.0n  c2.0n   GOL     $60   re-make Puch,  made in Italy by GOL
000000the real 1 20.0  37.96  c1.5n  c1.5n  generic $55   re-make Puch,  made in Taiwan
000000233709    20.6  37.95  t1.5n   t1.5n  Vertex  none  original  Tomos A55 alu cyl, pre-07 with trap. rings
000000233709    20.6  37.95  c1.5n  c1.5n  Vertex  none  original  Tomos A55 alu cyl = 37.98 07-09 14140 37.98
000000409000    18.0  37.95  c1.5n  c1.5n  generic none  re-make Tomos A35
000000223747    18.0  37.95  c1.5n  c1.5n  Vertex  $68   original  Tomos A35 std, has windows on in side
0000.802.5090    23.0  37.95  L2.0n  c1.5n  Mahle   $70   original  Derbi 1976-86     says B
000000 000000   20.5  37.95  c2.0n  none   Mahle   $72   original  Puch ’84 alu 37.99 sort C  says 38 C 1734
349.110.0069/21 20.5  37.95  c2.0n  c2.0n  Mahle   none  original  Puch alu cyl 37.98 sort 1   says 38 1 1019
349.110.0069/22 20.5  37.96  c2.0n  c2.0n  Mahle   none  original  Puch alu cyl 37.99 sort 2   says 38 2 1019
349.110.0069/23 20.5  37.97  c2.0n  c2.0n  Mahle   none  original  Puch alu cyl 38.00 sort 3   says 38 3 1019
349.110.0069/24 20.5  37.98  c2.0n  c2.0n  Mahle   $65   original  Puch alu cyl 38.01 sort 4   says 38 4 1019
349.110.0069/25 20.5  37.99  c2.0n  c2.0n  Mahle   $75   original  Puch alu cyl 38.02 sort 5   says 38 5 1019
350.310.0069/03 22.0  37.95  c2.0n  c2.0n  Mahle   none  original  Puch HT cyl 38.00 sort 11 says 38 1 1116
350.310.0069/04 22.0  37.96  c2.0n  c2.0n  Mahle   none  original  Puch HT cyl 38.01 sort 22 says 38 2 1116
349.210.5069/11 23.0  37.95  L2.0n  c2.0n  Mahle   none  original  Puch HT cyl 38.00 sort 11 says 38.0 11 1593a
349.210.5069/22 23.0  37.96  L2.0n  c2.0n  Mahle   none  original  Puch HT cyl 38.01 sort 22 says 38.0 22 1593a
349.210.5069/33 23.0  37.97  L2.0n  c2.0n  Mahle   $65   original  Puch HT cyl 38.02 sort 33 says 38.0 33 1593a
000000  part#   lower  @skirt  ring1  ring2   maker  price    38.25 bore, 12 pin, 17 uppe
0000.802.5091    20.0  38.18  L2.0n  c1.5n  Mahle   $40   original  1os Derbi 1976-86 says 0.25 B or 0.25 C 
0000.802.5091    20.0  38.18  L2.0 L2.0n  Mahle   $40   original  1os Derbi  same but both rings L-type!

0000.802.5091    20.0  38.18  L2.0n  c1.5n  Mahle   $35   original  1os Derbi 1976-86 says 38.205 JG 0.045
349.310.4669/03 23.0  38.19  L2.0n  c2.0n  Mahle   $75   original  1os Puch HT cyl 11 says 38.25 11 1593a
349.310.4669/04 23.0  38.20  L2.0n  c2.0n  Mahle   $75   original  1os Puch HT cyl 22 says 38.25 22 1593a
000000  part#   lower  @skirt  ring1  ring2   maker  price    38.4 bore, 12 pin, 17 upper
0000.802.5092    20.0  38.3?  L2.0n  c1.5n  Mahle   none  original  2os Derbi 1976-1986
000000  part#   lower  @skirt  ring1  ring2   maker  price    38.5 bore, 12 pin, 17 upper
000000227334    20.5  38.4x  c1.5n  c1.5n  Vertex  none  original  1os Tomos A35
000000409001    20.x  38.4x  c1.5n  c1.5n  generic $60   re-make 1os Tomos A35
000000  part#   lower  @skirt  ring1  ring2   maker  price    38.7 bore, 12 pin, 17 upper
0000.802.5093    20.0  38.6x  L2.0n  c1.5n  Mahle   none  original  3os Derbi 1976-1986
000000  part#   lower  @skirt  ring1  ring2   maker  price    38.9 bore, 12 pin, 17 upper
0000.802.5094    20.0  38.8x  L2.0n  c1.5n  Mahle   none  original  4os Derbi 1976-1986
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.0 bore, 12 pin, 17 upper
00 70.06.04.00    18.0  39.9x  c1.5n  c1.5n  Asso    none  original  Benelli 1965-80 (old# G7346)
00 70.06.04.00a  18.0  39.95  c1.5n  c1.5n  GOL     $65   re-make Benelli 1965-80
000000000000    19.0  39.94  t1.5n   t1.5n  Yamaha $60   original  Yamaha model?  complete
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.2 bore, 12 pin, 17 upper
00 70.06.04.02    18.0  40.1x  c1.5n  c1.5n  Asso    none  original  1os Benelli 1965-80 (old# G7346/2)
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.25 bore, 12 pin, 17 upper
000000000000    19.0  40.22  t1.5n   t1.5n  Yamaha $30   original  1os Yamaha model?  without rings
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.4 bore, 12 pin, 17 upper
00 70.06.04.04    18.0  40.3x  c1.5n  c1.5n  Asso    none  original  2os Benelli 1965-80 (old# G7346/4)

17mm upper (12 pin) Puch

Puch

17mm upper (12 pin) Derbi Variant pre-'87

Derbi pre-’87

17mm upper, 12mm pin, Tomos A35 1992-06

Tomos A35

17mm upper, 12 pin, Benelli

Benelli

Tomos A55

 

 

 

 

 

 
 

12-18  86-89 Derbi, 70-90 Garelli, 72-80 Batavus, 81-89 Trac

000000  part#   lower  @skirt  ring1  ring2   maker  price    40.0 bore, 12 pin, 18 upper
0F0.250.0091/A   19.0  39.945 c1.5i   c1.5i   Mahle   none  original  Derbi 1986-1989 flat reed eng, Sort A
0F0.250.0091/B   19.0  39.95  c1.5i   c1.5i   Mahle   none  original  Derbi 1986-1989 flat reed eng, Sort B
0F0.250.0091/C   19.0  39.955 c1.5i   c1.5i   Mahle   none  original  Derbi 1986-1989 flat reed eng, Sort C
0F0.250.0091/D   19.0  39.96  c1.5i   c1.5i   Mahle   none  original  Derbi 1986-1989 flat reed eng, Sort D
0F0.250.0091/E   19.0  39.965 c1.5i   c1.5i   Mahle   none  original  Derbi 1986-1989 flat reed eng, Sort E
0000000408211  14.0  39.92   c1.5n  c1.5n  generic $70   re-make Daelim (Trac) aftermarket (rect. rings)
0000000408201  16.0  39.92   c2.0n  c2.0n  generic $60   re-make Garelli/Batavus aftermarket
000000 0??????   14.0  39.9x   t1.5n   t1.5n  generic none  original  Daelim (Trac) original (trap. rings)
0000000480580  14.0  39.95   c1.5n  c1.5n  Mahle   none  original  Batavus M48 original says 39.95
0000000080016  14.0  39.9x   c1.5n  c1.5n  Mahle   none  original  Batavus/Trac M56 original Sort A
0000000080017  14.0  39.9x   c1.5n  c1.5n  Mahle   none  original  Batavus/Trac M56 original Sort B
0000000080018  14.0  39.98   c1.5n  c1.5n  Mahle   none  original  Batavus/Trac M56 original Sort C
0000000080019  14.0  39.9x   c1.5n  c1.5n  Mahle   none  original  Batavus/Trac M56 original Sort D
0000000080020  14.0  40.0x   c1.5n  c1.5n  Mahle   none  original  Batavus/Trac M56 original Sort E
0000000 ??????   14.0  40.0x   c1.5n  c1.5n  Mahle   none  original  Batavus/Trac M56 original Sort F
00205058.2.150  xx.x   39.9x   c2.0n  c2.0n  Asso    none  original  flat top, Garelli alum cylinder 20, 25mph
00205088.2.150  xx.x   39.9x   c2.0n  c2.0n  Asso    none  original  flat top, Garelli alum. cylinder  30mph
00200001.2.150  16.0  39.9x   c2.0n  c2.0n  Asso    none  original  Garelli iron cylinder 20,30mph
00205053.2.150  17.0  39.9x   c2.0n  c2.0n  Asso    none  original  Garelli iron cylinder 25mph
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.2 bore, 12 pin, 18 upper
00200001.2.151  16.0  40.1x   c2.0n  c2.0n  Asso    none  original  1os Garelli iron cylinder 20, 30mph
00205053.2.151  17.0  40.1x   c2.0n  c2.0n  Asso    none  original  1os Garelli iron cylinder 25mph
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.25 bore, 12 pin, 18 upper
0000000480581  14.0  40.20   c1.5n  c1.5n  Mahle   $75   original  1os Batavus with Laura M48 engine
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.40 bore, 12 pin, 18 upper
00200001.2.152  16.0  40.3x   c2.0n  c2.0n  Asso    none  original  2os Garelli iron cylinder 20, 30mph
00205053.2.152  17.0  40.3x   c2.0n  c2.0n  Asso    none  original  2os Garelli iron cylinder 25mph
0000000534404  17.0  40.33   c2.0n  c2.0n  GOL     $55   re-make 2os Garelli (made in Italy)
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.60 bore, 12 pin, 18 upper
00200001.2.153  16.0  40.5x   c2.0n  c2.0n  Asso    none  original  3os Garelli iron cylinder 20, 30mph
00205053.2.153  17.0  40.5x   c2.0n  c2.0n  Asso    none  original  3os Garelli iron cylinder 25mph
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.80 bore, 12 pin, 18 upper
00200001.2.154  16.0  40.7x   c2.0n  c2.0n  Asso    none  original  4os Garelli iron cylinder 20, 30mph
00205053.2.154  17.0  40.7x   c2.0n  c2.0n  Asso    none  original  4os Garelli iron cylinder 25mph

18mm upper, 12 pin Daelim (Trac)

Daelim (Trac)

Batavus

18mm upper, 12 pin, Garelli

Garelli

Garelli piston markings

 

 

 

 

 

 

Asso

Garelli 4th oversize 40.8mm piston, made by Asso, says “40.8”. You can see it’s bigger. Middle, Garelli standard 40.0mm piston, made by Asso, says “40” and “S”. The “S” means scoria, Italian for exhaust. Right, Garelli standard 40.0mm piston, aftermarket. All three are oriented with the exhaust side down, like in the engine.

 

Kreidler

12-19  1970’s Kreidler Flory, 1990 Honda NS50

000000  part#   lower  @skirt  ring1  ring2   maker  price    39.0 bore, 12 pin, 19 upper
13101-GE2-305   16.0  38.94  t1.2n  c1.2n  generic none  Honda NS50 1990
000000  part#   lower  @skirt  ring1  ring2   maker  price    39.25 bore, 12 pin, 19 upper
13102-GE2-305   16.0  39.19  t1.2n  c1.2n  generic none  1os Honda NS50 1990
000000  part#   lower  @skirt  ring1  ring2   maker  price    39.5 bore, 12 pin, 19 upper
13103-GE2-305   16.0  39.44  t1.2n  c1.2n  generic none  2os Honda NS50 1990
000000  part#   lower  @skirt  ring1  ring2   maker  price    39.75 bore, 12 pin, 19 upper
13104-GE2-305   16.0  39.69  t1.2n  c1.2n  generic none  3os Honda NS50 1990
000000  part#   lower  @skirt  ring1  ring2   maker  price    40.0 bore, 12 pin, 19 upper
00002150383d    15.2  39.93  c1.5i   c1.5i   Mahle   $80   Kreidler Flory alu cyl 39.98 sort D  says R021 40154+
00002150383f     15.2  39.96  c1.5i   c1.5i   Mahle   none  Kreidler Flory alu cyl 39.99 sort F   says R021 40154+
00002150383h    15.2  39.73  c1.5i   c1.5i   Mahle   $60   (worn used)   alu cyl 40.00 sort H  says R021 40154+
00002150383m   15.2  39.98  c1.5i   c1.5i   Mahle   none  Kreidler Flory alu cyl 40.01 sort M  says R021 40154+

 
 

12-20  Vespa (Piaggio), 1995-05 Kinetic TFR

  part#   lower  @skirt   ring1   ring2   maker  price    38.2 bore, 12 pin, 20 upper
182591    16.0  38.12  2.0FG  2.0FG  Piaggio   $60   original  Vespa US ’78-80 Ciao Bravo Grande says USA
191034    16.0  38.1x  Dykes  1.5FG  Piaggio  none  original  Vespa US ’79-86 Si, ’80-86 Ciao Bravo Grande
  part#   lower  @skirt   ring1   ring2   maker  price    38.4 bore, 12 pin, 20 upper
Kinetic     16.0  38.30  1.5-3F 1.5-3F  generic  none  original  Kinetic    ’95-05 (Vespa remake) no arrow
112979    16.0  38.3x  2.0FG  2.0FG  Piaggio  none  original  Vespa  all ’67-76 Ciao & Boxer, new# is 132521
132521    16.0  38.32  2.0FG  2.0FG  Piaggio  $50   original  Vespa US ’76-78 Ciao, ’77-78 Bravo
182592    16.0  38.32  Dykes  1.5FG  Piaggio  $65   original  1os Vespa US ’78-86 Ciao Bravo Grande Si says 1M
  part#   lower  @skirt   ring1   ring2   maker  price    38.6 bore, 12 pin, 20 upper
152381    16.0  38.54  2.0FG  2.0FG  Piaggio  none  original  1os Vespa  all ’67-76 Ciao & Boxer, new# is 137681
137681    16.0  38.54  Dykes  2.0FG  Piaggio  none  original  1os Vespa US ’76-78 Ciao, ’77-78 Bravo    says 1M
182593    16.0  38.5x  Dykes  1.5FG  Piaggio  none  original  2os Vespa US ’78-86 Ciao Bravo Grande Si says 2M
  part#   lower  @skirt   ring1   ring2   maker  price    38.8 bore, 12 pin, 20 upper
152382    16.0  38.74  2.0FG  2.0FG  Piaggio  $60   original  2os Vespa  all ’67-76 Ciao & Boxer, new# is 137682

137682    16.0  38.74  Dykes  1.5FG  Piaggio  $60   original  2os Vespa US ’76-78 Ciao, ’77-78 Bravo   says 2M
  part#   lower  @skirt   ring1   ring2   maker  price    40.0 bore, 12 pin, 20 upper
633992    17.0  39.9x 1.2-0F 1.2-0F  generic  $60   re-make China 49cc two-strokes

20mm upper, 12mm pin, Vespa

20-12 x 38.4 Vespa

20mm upper, 12 pin, Vespa L-ring

20-12 x 38.2 Vespa

20mm upper, 12 pin, China two stroke

20-12 x 40 China

Vespa moped “USA” piston and cylinder

 

 

 

 

 

 

 

 

Ch-ch-changes: Vespa standard pistons changed in 1978 and 1980. Bikes made during those years can have either the older or the newer piston. There is no way to tell by ID numbers.

1978 bore reduction: In 1978 on US models the bore was reduced from 38.4 to 38.2mm. Some ’78’s have a 38.4 bore, and some have a 38.2 bore. Same thing happened to Minarelli at that same time (a reduction from 38.8 to 38.7). The pistons changed because of legal requirements.

1979-80 Dykes upper ring: In 1979 and 1980 the upper piston ring changed to L shape known as Dykes. Some ’79’s have regular top rings, and some have Dykes. Oversize Piaggio pistons already had Dykes upper rings since about 1977. This ring style was also adopted by Derbi in the mid-70’s and Puch in the late 70’s. It was mainstream in 1979! But by the mid-1980’s L-rings became out of style and obsolete. They did cost more to make, and broke easier. There was not much benefit. So all 90’s and later two-stroke moped engines have rectangular or trapezoidal top rings, mostly thinner than older designs.  

SC means exhaust (scoria): All original pistons are made by Piaggio and say Piaggio or have the logo on the inner side. They all have an arrow on top with the letters “SC”. That means “scoria”, Italian for “exhaust”. During installation, the arrow points toward the exhaust. Vespa pistons have skirt cut-outs rotated 30 deg.

Ring gap: Piaggio specifies the ring gap to be 0.1 to 0.25 mm (0.004 to 0.010″)

10 or 12mm piston pins: All of the Vespa moped pistons below have 12mm wrist pins. There are some (as yet unknown) non-US models with 10mm wrist pins.

Piston versions: By having all of the Piaggio Parts Manuals, and especially the Parts Amendments 1, 2, 3 etc, it was possible to extract all of the Vespa (Piaggio) moped piston and ring part numbers. The millimeter sizes are not in any parts manual. They are from service manuals and actual parts new and used.

 


12-21  Minarelli V1L V1HL V1HLE, Suzuki FA50 FS50 FZ50

0000000000  part#   lower  x = 2, 3, or 4
000000
  part#   lower  @skirt   ring1   ring2   maker  price    40.3 bore, 12 pin, 21.5 upper

00000004541      15.0  40.2x   Dykes  1.5FG  Minn.   none  original  Minarelli V1L case reed, all-iron cylinder
00000004543      15.0  40.2x   1.5FG  1.5FG  Minn.   none  original  Minarelli V1HL case reed, sleeved al. cyl.
000000  part#   lower  @skirt   ring1   ring2   maker  price    40.6 bore, 12 pin, 21.5 upper
00000004551      15.0  40.5x   Dykes  1.5FG  Minn.   none  original  1os Minarelli V1L
00000004553      15.0  40.5x   1.5FG  1.5FG  Minn.   none  original  1os Minarelli V1HL, V1HLE
000000  part#   lower  @skirt   ring1   ring2   maker  price    40.8 bore, 12 pin, 21.5 upper
00000004561      15.0  40.7x   Dykes  1.5FG  Minn.   none  original  2os Minarelli V1L
00000004563      15.0  40.7x   1.5FG  1.5FG  Minn.   none  original  2os Minarelli V1HL, V1HLE
000000  part#   lower  @skirt   ring1   ring2   maker  price    41.0 bore, 12 pin, 21 upper
0012110.43000   15.0  40.92  1.5-3G 1.3-3G Suzuki  none  original  Suzuki FA50, FS50, FZ50
000000  part#   lower  @skirt   ring1   ring2   maker  price    41.5 bore, 12 pin, 21 upper
12100.35611.050 15.0 41.4x  1.5-3G 1.3-3G Suzuki  none  original  1os Suzuki FA50, FS50, FZ50
000000  part#   lower  @skirt   ring1   ring2   maker  price    42.0 bore, 12 pin, 21 upper
12100.35611.100 15.0 41.9x  1.5-3G 1.3-3G Suzuki  none  original  2os Suzuki FA50, FS50, FZ50

21mm upper, 12 pin, Suzuki FA50

12 pin, 21 upper, Suzuki FA50

 

 

 

 

 

 

 

 


12-22  Minarelli V1, V1H, Sachs 504, 505, Morini S5

000000  part#   lower  @skirt   ring1   ring2   maker  price    38.0 bore, 12 pin, 22 upper
000000406500 .   13.5  37.95  1.5FG  2.0FG generic $55   re-make Sachs 504,505 1C,1D  says 38
00286-378-051    14.0  37.95  1.5FG  2.0FG  Mahle  none  original  Sachs 504,505 1C,1D  553
000000000000.   16.0  37.95  2.0FG  2.0FG  AMF    $60   original AMF BHE900 rear engine  says 38

00286-378-005    16.0  37.96  2.0FG  2.0FG  Mahle  $75   original  Sachs 504,505 1A,1B  552 says 37.98 G8
0000PC0922D      16.0  37.96  2.0FG  2.0FG  Meteor $60   re-make Sachs 504,505 1A,1B  Italian made
0000023-0101     16.0  37.93  2.0FG  2.0FG  Asso    none  original  Morini S5K, S5K2         says Asso 771
71.0455.0  4500  15.0  37.93  2.5FG  2.5FG  Asso    $75   original  Minarelli V1 1hp 20mph says Asso 825
000000  part#   lower  @skirt   ring1   ring2   maker  price    38.2 bore, 12 pin, 22 upper
71.0455.7  4510  16.0  38.1x  2.5FG  2.5FG  Asso    none  original  1os Minarelli V1 1hp 20mph
0000023-0102     17.0  38.1x  2.0FG  2.0FG  Asso    none  original  1os Morini S5K2, can use Minarelli #4510?
000000  part#   lower  @skirt   ring1   ring2   maker  price    38.4 bore, 12 pin, 22 upper
71.0455.7  4520  16.0  38.3x  2.5FG  2.5FG  Asso    none  original  2os Minarelli V1 1hp 20mph
000000  part#   lower  @skirt   ring1   ring2   maker  price    38.6 bore, 12 pin, 22 upper
71.0455.7  4530  16.0  38.5x  2.5FG  2.5FG  Asso    none  original  3os Minarelli V1 1hp 20mph
00286-378-006    16.0  38.55  2.0FG  2.0FG  Mahle  $60   original  1os Sachs 504,505 1A,1B
00286-378-052    14.0  38.55  1.5FG  2.0FG  Mahle  none  original  1os Sachs 504,505 1C,1D
000000  part#   lower  @skirt   ring1   ring2   maker  price    38.7 bore, 12 pin, 22 upper
71.0406.0  4535  16.0  38.62  1.5FG  1.5FG  Minn.   none  original  Minarelli V1 ’78-on-USA
000000  part#   lower  @skirt   ring1   ring2   maker  price    38.8 bore, 12 pin, 22 upper
000004540HP      15.5  38.73  Dykes  2.0FG  Asso    $60   original  Demm Smily piston, fits Minarelli
71.0410.0  4540  16.0  38.72  1.5FG  1.5FG  Minn.   $75   original  Minarelli V1 pre-’79-USA, P4 w/iron cyl
0000000034        16.0  38.72  1.5FG  1.5FG  GOL     $60   re-make Minarelli V1
000000  part#   lower  @skirt   ring1   ring2   maker  price    39.0 bore, 12 pin, 22 upper
71.0460.7  4550  16.0  38.92  1.5FG  1.5FG  Minn.   $75   original  1os Minarelli V1
000023-0133A     15.0  38.94  Dykes  2.0GI  Asso    none  original  Unknown, no rings, says Asso 1386
000023-0133A     16.0  38.98  Dykes  1.5FG  Asso    none  original  Morini S5R, S5T (alum cyl 1sp kick)
000023-0133B     16.0  38.97   Dykes  1.5FG  Asso    none  original  Morini S5R, S5T (alum cyl 1sp kick)
000023-0133C     16.0  38.96   Dykes  1.5FG  Asso    none  original  Morini S5R, S5T (alum cyl 1sp kick)
000023-0133D     16.0  38.95   Dykes  1.5FG  Asso    none  original  Morini S5R, S5T (alum cyl 1sp kick)
000023-0133E     16.0  38.94   Dykes  1.5FG  Asso    none  original  Morini S5R, S5T (alum cyl 1sp kick)
000023-0133F     16.0  38.93   Dykes  1.5FG  Asso    none  original  Morini S5R, S5T (alum cyl 1sp kick)
000000  part#   lower  @skirt   ring1   ring2   maker  price    39.2 bore, 12 pin, 22 upper
71.0460.7  4560  16.0  39.12  1.5FG  1.5FG  Minn.   none  original  2os Minarelli V1
000000  part#   lower  @skirt   ring1   ring2   maker  price    39.4 bore, 12 pin, 22 upper
71.0460.7  4570  16.0  39.32  1.5FG  1.5FG  Minn.   $75   original  3os Minarelli V1

0000000000        16.0  39.3x  1.5FG  1.5FG  Minn.   none  original  Harley Davidson M50 std
000000  part#   lower  @skirt   ring1   ring2   maker  price    39.6 bore, 12 pin, 22 upper

71.0460.7  4580  16.0  39.52  1.5FG  1.5FG  Minn.   none  original  4os Minarelli V1

000000  part#   lower  @skirt   ring1   ring2   maker  price    39.8 bore, 12 pin, 22 upper

71.0460.7  4590  16.0  39.7x  1.5FG  1.5FG  Minn.   none  original  5os Minarelli V1
000000  part#   lower  @skirt   ring1   ring2   maker  price    40.0 bore, 12 pin, 22 upper

0208703.2.150   16.0  39.9x  1.5FG  1.5FG  Asso?   none  original  Garelli Monza GT, has port window(s), flat top
000000  part#   lower  @skirt   ring1   ring2   maker  price    45.4 bore, 12 pin, 22 upper

71.0485.7 0000  18.0  45.33  1.5FG  1.5FG  Minn.   $70   original  Minarelli 70cc new in box
000000  part#   lower  @skirt   ring1   ring2   maker  price    46.0 bore, 12 pin, 21.5 upper
0000023-0140     14.5  45.93  Dykes  1.5GI  Asso    $70   original  Morini 70cc, says Asso W 2508, 
000000  part#   lower  @skirt   ring1   ring2   maker  price    47.1 bore, 12 pin, 22.5 upper

0000023-01??     14.5  47.03  Dykes  1.5GI  Asso    $70   original  Morini 70cc, says AW 2666, AA on top

22mm upper, 12mm pin, Morini S5E piston 23-0133 D

12-22 Morini S5

16mm pin-edge to crown-edge, 12 pin, Morini S5 series (1970's -2002)

12-22 x 39 Morini S5

Morini-Minarelli-Sachs connection

22mm upper, 12 pin, Minarelli V1

Minarelli V1

22mm upper, 12 pin, Sachs 504/505

Sachs 504

 

 

 

 

 

.
<Left   1971-79? Morini S5K2 xxxxxxxxxx 23-0101  Ø38.0 22 x 12 x 17
<Right 1972-78  Sachs 504 xxxxxxx 0286.378.005  Ø38.0 22 x 12 x 16
Middle 1969-79  Minarelli V1 20 mph xxxxxx  4500  Ø38.0 22 x 12 x 16
Middle 1951-55  FBM P48, P3, 1956-66 Morini F1, 3M

Connection: Erio Testi worked in his father’s bicycle factory until 1953, when he was sent to Austria, at Fichtel and Sachs, to learn about small two stroke engines. After Testi returned, he transferred the two stroke engine knowledge to his friend Vittorio Minarelli, who was partners with Franco Morini at Fabricca Bologna Minarelli FBM. The two Italian engineers used many of German engineer Ernst Sachs production methods and knowledge, like casting and metallurgy, and design principles, like bore and stroke, port timing, sizes and thicknesses, geometry, etc. Later FBM split into Motori Morini Franco and Motori Minarelli. That’s why early Sachs, Morini, and Minarelli pistons share the same design!

Asso Pistons

ASSO Pistons

Asso Factory

ASSO Factory

Asso

 

ASSO pistons were made in Italy mostly for Italian mopeds. ASSO stands for Assoluta Sicurezza Sempre Ovunque (Absolute Security Any time Anywhere). Early pistons said only “ASSO”, while later 1980’s ones said “ASSO.W”. Somehow ASSO merged with or was acquired by a German name, maybe some “kolben werke” to become ASSO Werke.

 

 

 


12-23 Casal M140 engine on K177, Zundapp?Mahle

  part#   lower  @skirt  ring1  ring2   maker  price    40.0 bore, 12 pin, 23 upper
00Casal   16.0  39.9x  c2.0n  c2.0n  Mahle   none  original Casal al cyl 39.9x sort D says <–saida D  Mahle 401
00Casal   16.0  39.9x  c2.0n  c2.0n  Mahle   $70   original Casal al cyl 39.9x sort E says <–saida E  Mahle 401
00Casal   16.0  39.9x  c2.0n  c2.0n  Mahle   none  original Casal al cyl 39.9x sort F says <–saida F  Mahle 401
  part#   lower  @skirt  ring1  ring2   maker  price    48.0 bore, 12 pin, 23 upper
00Casal   16.0  47.9x  c2.0n  c2.0n  Mahle   none  original Casal al cyl 47.9x sort D says <–saida D  Mahle 481

00Casal   16.0  47.9x  c2.0n  c2.0n  Mahle   none  original Casal al cyl 47.9x sort E says <–saida E  Mahle 481
00Casal   16.0  47.9x  c2.0n  c2.0n  Mahle   none  original Casal al cyl 47.9x sort F says <–saida F  Mahle 481
0

Casal 40mm piston top

Casal Ø40 top

Casal 40mm piston bottom

says Mahle 401

Casal Ø48 Piston top

Casal Ø48 top

Casal Ø48 piston bottom

says Mahle 481

 

 

 

 

 

 

 

Casal (made in Portugal) pistons are made in Germany by Mahle. They say “saida” on top, exhaust side, Portuguese for “outlet”. They have an unusual flat bottom. They have a total height of 50mm. Top edge to pin is 23mm, plus pin 12mm, plus pin to bottom edge 15mm. There are two bore choices 40 and 48mm, each with several 0.01mm (micro!) increments to get a precise fit. A cylinder of letter “F” should get a matching “F” piston, unless it is worn, then maybe a “G” or even an “H” would be best. If the piston fit is too loose the engine will be weak, noisy, and fussy. Too tight and it will seize and do damage. Piston rings are both size 40 x 2.0 FG gap style, like Garelli. 

 


Indian 4-stroke

13-13 Indian 78-84 AMI-50, 75-77 Honda PC50K1

000000  part#   lower  @skirt  ring1  ring2   maker  price    42.0 bore, 13 pin, 13.5 upper
bare E650-00-50 13.5  41.96 1.2flat 1.2flat generic  none  original  Indian AMI50, Hon PC50K1
complete 6131 0 13.5  41.96 1.2flat 1.2flat generic  $70   re-make Indian AMI50, Hon PC50K1

000000  part#   lower  @skirt  ring1  ring2   maker  price    42.25 bore, 13 pin, 13.5 upper
bare E650-10-50 13.5  42.21 1.2flat 1.2flat generic  $45   original  1os In AMI50, Hon PC50K1
complete 6132 0 13.5  42.21 1.2flat 1.2flat generic  $70   re-make 1os In AMI50, Hon PC50K1

 


13-15 Motobecane 1977-80 40, 50, 50V Mobylette

  part#   lower  @skirt  ring1  ring2   maker  price    39.0 bore, 13 pin, 15.5 upper
22273      21.5  38.92  c2.0i   c2.0i   MBK     $60   Motobecane alu cyl 38.95 sort 2
22274      21.5  38.93  c2.0i   c2.0i   MBK     none  Motobecane alu cyl 38.96 sort AA
22275      21.5  38.94  c2.0i   c2.0i   MBK     none  Motobecane alu cyl 38.97 sort A
22276      21.5  38.95  c2.0i   c2.0i   MBK     none  Motobecane alu cyl 38.98 sort C
22277      21.5  38.96  c2.0i   c2.0i   MBK     $65   Motobecane alu cyl 38.99 sort E
22278      21.5  38.97  c2.0i   c2.0i   MBK     $65   Motobecane alu cyl 39.00 sort G
22279      21.5  38.98  c2.0i   c2.0i   MBK     none  Motobecane alu cyl 39.01 sort J
22280      21.5  38.99  c2.0i   c2.0i   MBK     none  Motobecane alu cyl 39.02 sort L
22281      21.5  39.00  c2.0i   c2.0i   MBK     $65   Motobecane alu cyl 39.03 sort N
22435      21.5  39.01  c2.0i   c2.0i   MBK     $65   Motobecane alu cyl 39.04 sort P  says P
  part#   lower  @skirt  ring1  ring2   maker  price    39.15 bore, 13 pin, 15.5 upper
22435a    21.5  39.11  c2.0i   c2.0i   MBK     $65   1os Motobecane cyl 39.14 very worn?

 


Jawa USA

14-18 Jawa Babetta 207 series

000000  part#   lower  @skirt   ring1   ring2   maker  price    39.0 bore, 14 pin, 18 upper
0000281218a       15.0  38.94  Dykes  none  Meteor  none  re-make Jawa 210?  2 x 1 L-ring groove

000000
  part#   lower  @skirt   ring1   ring2   maker  price    39.03 bore, 14 pin, 18 upper

0000281218A      15.0  38.97  2.0GI  2.0GI    Jawa    none  original  Jawa 207, no pin or clips, says A Y
0000281218B      15.0  38.98  2.0GI  2.0GI    Jawa    none  original  Jawa 207, no pin or clips, says B Y
0000281218C      15.0  38.99  2.0GI  2.0GI    Jawa    none  original  Jawa 207, no pin or clips, says C Y
000000  part#   lower  @skirt   ring1   ring2   maker  price    39.28 bore, 14 pin, 18 upper
0000281218/1A   15.0  39.22  2.0GI  2.0GI    Jawa    none  original  1os Jawa, no pin or clips, says 1A Y
0000281218/1B   15.0  39.23  2.0GI  2.0GI    Jawa    $60   original  1os Jawa, no pin or clips, says 1B Y
0000281218/1C   15.0  39.24  2.0GI  2.0GI    Jawa    none  original  1os Jawa, no pin or clips, says 1C Y
000000  part#   lower  @skirt   ring1   ring2   maker  price    39.53 bore, 14 pin, 18 upper
0000281218/2A   15.0  39.47  2.0GI  2.0GI    Jawa    none  original  2os Jawa, no pin or clips, says 2A Y
0000281218/2B   15.0  39.48  2.0GI  2.0GI    Jawa    none  original  2os Jawa, no pin or clips, says 2B Y
0000281218/2C   15.0  39.49  2.0GI  2.0GI    Jawa    none  original  2os Jawa, no pin or clips, says 2C Y

000000  part#   lower  @skirt   ring1   ring2   maker  price    39.78 bore, 14 pin, 18 upper
0000281218/3A   15.0  39.72  2.0GI  2.0GI    Jawa    none  original  3os Jawa, no pin or clips, says 3A Y
0000281218/3B   15.0  39.73  2.0GI  2.0GI    Jawa    none  original  3os Jawa, no pin or clips, says 3B Y
0000281218/3C   15.0  39.74  2.0GI  2.0GI    Jawa    none  original  3os Jawa, no pin or clips, says 3C Y

000000  part#   lower  @skirt   ring1   ring2   maker  price    40.03 bore, 14 pin, 18 upper
0000281218/4A   15.0  39.97  2.0GI  2.0GI    Jawa    none  original  4os Jawa, no pin or clips, says 4A X
0000281218/4B   15.0  39.98  2.0GI  2.0GI    Jawa    $65   original  4os Jawa, no pin or clips, says 4B X
0000281218/4C   15.0  39.99  2.0GI  2.0GI    Jawa    none  original  4os Jawa, no pin or clips, says 4C X

Jawa has 3 sorts times 5 sizes

Jawa PistonsJawa pistons have 14mm piston pins, thicker than most other 50cc piston pins. There is not a good substitute for Jawa piston, not even one with a smaller pin. 

Markings: The marking on top tells the sort (A,B or C) and the size (std or 1,2,3,4).

 

 Size translation: The table says a “1B” piston is 39.21 mm, measured “34,5mm from the base” just below the lower ring. Four “1B” pistons actually measured 39.21 there, and 39.23 at the skirt. Other “1B” pistons were 39.20 and 39.22, 39.21 and 39.22, and 0.02 more at the skirt. Other samples were “B” (standard) 38.94 and 38.96, “2B” 39.44 and 39.46, “3B” 39.70 and 39.73, “4B” two at 39.95 and 39.97, all 0.02 wider at the skirt. Based on these eleven new pistons, all measured the same way at the same time, the Jawa piston sizes can be translated to standard piston sizes. Jawa piston sizes (measured at the lower ring) are, on average, 0.02 mm less than standard piston sizes (measured at the skirt).

Piston to cylinder clearance: From the Puch service manual the piston to cylinder clearance for a similar steel sleeved aluminum cylinder, is min 0.030, max 0.055 mm. From the Jawa table of piston sizes (at right), it says the new piston-to-cylinder clearance is min 0.065, max 0.075 mm. Subtracting 0.02 mm from this gives min 0.045, max 0.055, more in agreement with Puch. 

 


Flandria

14-24 Flandria Bermuda

000000  part#   lower  @skirt   ring1   ring2   maker  price    40.0 bore, 14 pin, 24 upper
000000000000     11.5  39.9x  1.5FG  1.5FG Flandria none  Flandria Bermuda 1977

This is unusual in many ways. The transfer flows through the piston instead of around it.
The wrist pin is lowered to allow more intake air flow. This upper length of 24 is the most for 50cc pistons. The wrist pin measures 13.98 x 33 mm.

 

 

 

4. Piston Information

 

100’s more vintage replacement pistons of all sizes are in the GOL Pistons Vintage Catalog, a pdf download.