I have a 1980 Piaggio SI with literally no power. It starts very easy, it idles and it revs, but barely pulls itself forward. -let alone with me on it. Sounds good, but not very snappy when giving it throttle.
I have checked the following:
- It has spark.
- It has 125-130 PSI/8.5-9.0 bar compression.
- It has no decomp, hole welded shut.
- It has a overhauled rear gearbox with new bearings.
- It has .014" points gap, which results in points begin to open at about 20° BTDC.
- It has a newly overhauled engine, with new seals all around.
- No obvious leaks during leak-down test.
- It has fresh gas.
The moped have the following mods:
- Proma Circuit pipe
- SHA13.13 carb with a 62 jet
- Malossi air filter
- Malossi belt
Otherwise a stock variated SI.
My thoughts, which i hope to hear your two cents on:
The petcock is not new. I removed it when i painted the bike. I inspected it, cleaned it and could now see problems with it. When I have the fuel line off the carb it lets gas flow out, but only when turned to "reserve". The flow of fuel is good, but i dont know if its enough? Furthermore when replacing jets, the bowl has always been full of gas. Could the fuel-flow be too weak in any way?
If you have any other suggestions, I am more than happy to hear you out!