US-model Peugeot mopeds were made in three different speed and power versions to comply with different state laws. For example, mopeds in California go 30mph, but in Nevada or Arizona they go 25mph. Each state has different moped laws. Peugeot moped speed versions are referred to by the speed version codes U1, U2 and U3. The speed version code appears after the model on the I.D. plate, on the frame behind the headlight. For example, a 103 LVS U2 is a 25mph moped with 1.5 horsepower.
U1 is 20 mph and 1.0 hp, U2 is 25 mph and 1.5 hp, U3 is 30 mph and 2.0 hp
76-80 103 L2S U3 carb jet intake reed
6-80 103 L2S U3 size size pipe valve xx cylinder cyl. head x exhaust x clutch/variator gearing x seat wheels
102 No Variator
79-80 102 SPB U2 10 220 8.5 none xxx xx 102 all same xxx 102 all same fixed pulley 11 x 50T long spoke
79-80 102 SPB U3 12 245 12 none xxx xx 102 all same xxx 102 all same fixed pulley 11 x 42T solo spoke
79-80 102 SPB U3 12 245 12 none xxxxx 102 all same xxx 102 all same fixed pulley 11 x 42T long spoke
103 No Variator
76-77 103 LSS U1 8.5 240 8.5 restricted restricted lo-comp restricted xx fixed pulley 11 x 48T solo spoke
78-83 103 L2S U1 8.5 240 8.5 restricted restricted lo-comp restricted xx fixed pulley 11 x 48T solo spoke
78-80 103 L2S U2 12 245 12 restricted restricted lo-comp long baffle xx fixed pulley 11 x 40T solo spoke
78-80 103 L2S U3 12 245 12 restricted normal xx normalx long baffle xx fixed pulley 11 x 36T solo spoke
76-83 103 LVS U2 12 245 12 restricted restricted lo-comp long baffle xx U2 weightsx 11 x 52T solo spoke
78-80 103 SPS U2 12 245 12 restricted restricted lo-comp long baffle xx U2 weightsx 11 x 56T solo spoke
79-80 103 SPB U2 12 245 12 restricted restricted lo-comp long baffle xx U2 weightsx 11 x 56T long spoke
80-83 103 SPR U2 12 245 12 restricted restricted lo-comp long baffle xx U2 weightsx 11 x 56T long mags
76-78 103 LVS U3 12 245 12 normal x. normal xx normal x short baffle X U3 weightsx 11 x 52T solo spoke
78-83 103 LVS U3 12 245 12 normal x. normal xx normal x long baffle xx U3 weightsx 11 x 52T solo spoke
77-78 103 SPS U3 12 245 12 normal x. normal xx normal x short baffle x U3 weightsx 11 x 52T solo spoke
78-80 103 SPS U3 12 245 12 normal x. normal xx normal x long baffle xx U3 weightsx 11 x 52T solo spoke
79-80 103 SPB U3 12 245 12 normal x. normal xx normal x long baffle xx U3 weightsx 11 x 52T long spoke
80-83 103 SPR U3 12 245 12 normal x. normal xx normal x long baffle xx U3 weightsx 11 x 52T long mags
79-80 1oo TSM U3 12 245 12 normal x. TSM xxxx normal x TSM long xxx U3 weightsx 11 x 56T long spoke
Cylinder: 102 U2 and U3 are the same, but 103 U1,U2 have a different cylinder than 103 U3, with a slightly smaller exhaust port. A U1,U2 cylinder can be converted to U3 by mild “porting”, by grinding the top pf the port, at the cylinder wall, higher by 1.0 mm, and each side wider by 0.5mm.
Head: The 103 U1,U2 low compression head can be converted to U3 by milling off 1 or maybe 2 mm. Leaving off the head gasket instead, is a quick and beneficial way to increase the compression ratio. But when the head is moved closer to the piston, contact can happen. Care must be taken. A squish clearance of 0.6mm (0.024″) is recommended when cold. A minimum combustion chamber volume of 5.0cc is recommended for a 50cc swept volume, to have a maximum compression ratio of (50+5)/5 equals 11 to 1.
Reed Valve: The 103 U1 and U2 small round reed plate holes can be widened to “normal” round holes. Furthermore a Tomos A35 reed valve fits, and gives even more power increase because the reed plate holes are rectangles with more area. Expect a stock healthy 103 LVS U3 to go 4-5 mph faster and accelerate quicker, with just a Tomos reed valve, with no side effects.
Carburetor: To upgrade an 8.5 to a 12mm carburetor you can replace the bare body. It is too difficult to carve out because the non-removable brass spray tube is in the way.
Intake Pipe: To upgrade an 8.5 to a 12mm intake manifold you can carve out the inside, or replace it. On a Peugeot 102 the only difference between a U2 and U3 is the intake manifold.
Exhaust: The 103 U1 muffler is gloss black and has a U-turn in the removable baffle, and a hemispherical end cap. The 103 U2 and U3 muffler is dull black, with a straight tube removable baffle and a vertical channel end cap. The wider end of the vertical channel should face down, or the bike will go slower.
Baffle tube: Early 103 U3 models came with a short baffle tube. These went 35mph and were the fastest moped. Then in 1978 Peugeot had to slow all the bikes down to meet 30mph DOT requirements. They issued a recall to all 103 U3 owners to bring their mopeds into their dealer to have the long baffle put in. All later 103 U3 models were made with long baffles. Simply removing the baffle makes it only a little bit louder, but adds 2-3 mph in speed.
Belt Pulleys: The front pulley is the same on all 102 and 103-no-variator models. The variable front pulley on 103-variator models is the same except for the centrifugal variator weights are different on U2 and U3 models. All 102’s have the same 7 inch rear pulley. All 103’s have the same 8″ rear pulley.
Sprockets: All Peugeot’s have an 11 tooth front sprocket. 102 rear sprockets have smaller center holes than 103 rear sprockets (because the rear hub is smaller). 103 rear sprockets can interchange with Puch or Motobecane, except for the bolt holes. On both 102 and 103 Peugeot uses a special 5-hole pattern that is unique. They did not want people to easily change to a 6-hole Puch 45 tooth rear sprocket. It can be done with drilling.
Gearing: A smaller rear sprocket makes higher gearing, and higher possible speed. But if the gearing is already optimum, then higher gearing alone will not make any more speed, except on downhills and with tail winds. It takes a greater amount of driving force to push through the air at a greater speed, but higher gearing decreases the rear wheel driving force. So the engine has to make much more torque to achieve the higher speed.
Gearing: 102 and 103 no-variator have the same size front pulley, but the rear pulley is bigger on the 103, about 8 inch, while 102 is about 7 inch. So a 102 rear sprocket must be bigger by 8/7 to have the same overall gearing as a 103. That is why 102 rear sprockets are bigger than 103 no-variator ones.