Scooterotica

Has anyone got a link or ideas on how to test a Vespa Engine for an air leak, seen loads of info for Lambrettas but can't find much for a Vespa. I know I need to block off carb and exhaust but can't find how to do it.

Cheers bruce

here you go
http://www.scooterlab.uk/engine-pressur ... heap-tech/

Cheers but Seen that, its for a lammie rather than a Vespa, problem I have is blocking carb inlet off.

if you have an old inner-tube cut a piece big enough to cover bottom of the carb cut holes for the studs re-fit carb tighten down that's how i did it

For my vespa I think my exhaust stub pipe is not sealing tight against the cylinder. I sealed of the exhaust by clamping a rubber stopper in it. I took my carb off, cut a flat metal plate to seal the hole over the rotary pad, drilled a hole for a pipe through it, and cut a sheet of gasket for the bottom to seal it. I will test that area for air leaks, but when I pump I have zero air pressure and I have tested my pressure guage and bulb. I think air is coming out from where the exhaust meets the cylinder. I have been told that is a weak point of the vespa design, it doesnt make a good seal. What to do? Back the exhausts pipe out and try some gasket sealant on the threads and at the top?

Davidsquaredson wrote:For my vespa I think my exhaust stub pipe is not sealing tight against the cylinder. I sealed of the exhaust by clamping a rubber stopper in it. I took my carb off, cut a flat metal plate to seal the hole over the rotary pad, drilled a hole for a pipe through it, and cut a sheet of gasket for the bottom to seal it. I will test that area for air leaks, but when I pump I have zero air pressure and I have tested my pressure guage and bulb. I think air is coming out from where the exhaust meets the cylinder. I have been told that is a weak point of the vespa design, it doesnt make a good seal. What to do? Back the exhausts pipe out and try some gasket sealant on the threads and at the top?

Yes some high temp silicone sealant is what you need, re-fit and leave to set, then re-test, should fix your leak

Copper high temperature gasket on the threads, cut the fuel line down to minimum length to prevent air bubbles, and a new top end for the SI carb so needle and seat would close perfectly. After that problem solved. It was one or some combo of the above

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