Dellorto PHVA

Dell’Orto PHVA14

Welcome. This is a “third generation” Tomos carburetor, on US mopeds. It is preceded by two others, the Encarwi A83 on Tomos A3 1974-85, and the Dellorto SHA 14-12P on Tomos A3 1986-91 and A35 1992-06.

 

Dellorto PHVA14 Tomos A55 carburetor four views

 

Dellorto PHVA14 parts

0     N/A     233730 carburetor PHVA 14 DD  right side, no drain
1     $2.00 243115 rubber boot for cable
2     $6.00 243116 adjuster with nut M5-0.75
3     $8.00 243152 throttle cable guide 72º
4     $1.00 243118 carb top screw M5-0.80 x 14
5     N/A     243119 carburetor top cover
6     N/A     set only rubber “figure 8” gasket   see 40 below
6     N/A     set only
paper kind shown, actual kind is rubber
7     N/A     243120 throttle spring Ø12 x 52
    N/A     243121 throttle slide insert
9     N/A     243103 throttle slide #40 Ø15
10   $2.00 243122 needle E-clip for 1.5 clip groove
10a $2.00 phva10 substitute E-clip 1.5 mm
11   $30.0 243104 jet needle A07 2.0-1.0 x 38
11a $8.00 phva11 subst. needle  2.0-1.1 x 38
2.0 needle with 1.5 clip grooveDellorto PHVA throttle needle and substitute
“1.5” clip is 1.3 mm at opening

13   N/A     243125 choke lever bare
14   $4.00 phva14 rubber o-ring 18 x 20 
15   $0.80 243123 screw M4-0.70 x 10
16   N/A     243124 clamp for choke lever
17   N/A     243151 choke Assy 13,14,15,16
18   $8.00 243126 spring idle air Ø5 Ø7 x 9
19   $18.0 243147 idle air screw M5-0.50
21   $8.00 243128 spring idle speed Ø5 Ø7 x 14
22   $18.0 243148 idle speed screw M5-0.80
23   $17.0 243106 needle housing 209GA
23a $15.0 phva23 needle housing 210GA
24   $8.00 243160   main jet 55 M6-0.75 original A55
24a $6.00 D64x052 main jet 52 M6-0.75
24b none   D64x058 main jet 58 M6-0.75
24c $6.00 D64x060 main jet 60 M6-0.75
26   $8.00 243222       idle jet 25 M4-0.70 original A55
26a $8.00 D11600x29 idle jet 29 M4-0.70
26b $8.00 D11600x30 idle jet 30 M4-0.70
26c $8.00 D11600x32 idle jet 32 M4-0.70
26d $8.00 D11600x40 idle jet 40 M4-0.70
28   $6.00 243162 choke jet 40 M5-0.80
30   $25.0 243114 float all plastic bare  
31   $45.0 243149 float with needle valve
32   $35.0 243131 float needle valve  
34   N/A     set only float rubber o-ring  bigger than SHA
3
5   $7.00 243132 float hinge pin Ø2.0 x 19.5
36   N/A     243150 float bowl plastic

Dellorto PHVA Gaskets

Dellorto 52622 PHVA Gasket Set
Right: 6,14,34    Left: others

37  $0.80 027057 screw M4-0.70 x 18
40  $15.0 236460 gasket set 6, 14, 34
   $16.0 D52622 gasket set 6, 14, 34, others
   $5.00 others   gasket set others
45  $26.0 233740 intake silencer assy
46  $5.00 233741 air filter foam
47  $15.0 233748 junction sleeve   see note below
48  $2.00 221584 clamp 32-50

 

 

 

Notes

Junction sleeve 233748 on Tomos A55 models contains an air restrictor. Without derestriction, and with the stock catalytic exhaust, the stock jet is too big. Too much unburned fuel and oil are produced. That causes black goo to drip from the exhaust outlet, and soon clogs the catalytic converter. 

With derestriction, the stock jet size #55 becomes correct. The catalytic exhaust outlet stays super clean. No visible smoke is emitted. Only occasional water dribbles out, just like in modern cars. 

233748 joins carb and air filter

233748 A55 junction sleeve

233738 derestricted

 

 

 

 

 

 

 

 

 

Intake silencer 23340 on Tomos A55 models does more than just reduce noise. It reflects sound waves in a way that recovers or re-captures the mist of fuel and air that flows outward every down stroke of the piston. Remove the air box and a bigger jet is required. Less torque is produced and some fuel is wasted and gets on the rider’s right leg. Besides the magical shape and volume, the stock air box draws air from inside the frame. That air is at a slightly higher pressure than the moving air outside. Tomos engineers made the A55 engine super efficient in order to meet emissions standards in many countries. In doing that, too much power was produced, so restriction was needed to meet power and speed limits.