No power - Vespa Piaggio SI

Kristian Lomeland /
This single post is part of a larger thread. Start from the top or view this post in context.

Hi!

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!

Thanks! (edited)

This single post is part of a larger thread. Start from the top or view this post in context.

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account