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38.00 x 1.5/1.3 x 1.60 /7  T  N  $17.0 0..0000 223707 Tomos A55 (2001-06) superseded in ’07 to 236802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 2.00 1./x 1.7/0.7  C  N  $16

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 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 (after 06-76) Morini S5R lower
39.00 x 2.00 1./x 1.7/0.7  C  N  $10.0 000000   22148 Motobecane (before 07-75), DiBlasi mini-cycle
39.00 x 2.0/1.0 x 1.8/0.7  L  N  $19.0   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 00   310.001.00 Garelli Monza GT upper

40.00 x 2.50 1./x 1.7/0.7  C   I   $14.0 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  none    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  none  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 Carrabela 58cc stroke 42
42.00 x 2.00 1./x 1.7/0.7  C  N   N/A  0000000  00000 Puch DS60
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  4635HP big bore kit appr 60cc only 3
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  

 

 


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.