Vespa Bravo 49cc motor bicycle

[frankk]

Anybody on the forum have experience with one of these? Its been sitting in my tool shed for at least 25 years and now its time to pass it on to the grandkids. Before I started I flushed the tank, cleaned and set the points, disassembled and cleaned the carb and installed a new plug. one day it runs crappy and the next day it runs really crappy. Doesn't want to throttle up much past an idle, is hard to start and eventually it dies on its own when idleing. It has one of those decompression valves on the cylinder head to stop the engine. Anybody have ideas that could help? Frank

[HawkX66]

How did you clean the carb? I've found with some smaller ones it's very difficult to clean out all the orifices. If it were me, I'd look at the carb again and be sure to completely disassemble it and let it soak. Blow threw each orifice and make sure every one is cleaned out.

[PeteLeathersac]

'

Hawk's right also keep in mind torch tip cleaners are a great tool for cleaning carb orfices.
Any chance there's a critter nest/exhaust obstruction, worth a try running w/ pipe off?
If tank interior/anything of the fuel system questionable, bi-pass all w/ a gravity feed/remote fuel supply.
What of engine compression itself, could the decompressor be sticking/cable too tight/brkn. spring?
Ignition, try running in the dark watching for spark jumping also w/ a Spark Tester watching for erratic spark?
Best of luck!

~ Pete

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[frankk]

Thanks for the excellent tips guys. I actually did run a tip cleaner thru the jet. The carb and line are as clean as a whistle. The exhaust pipe and decompression valve was going to be the next thing I am going to look at. It does say in the owners manual to periodically decoke the pipe cylinder head and valve so historically these items could be problematic. Just don't know what I will do if the head has to come off. Finding an original head gasket could be as hard as finding Z16 parts