Vespa air leak kit

Anything related to Vespas... ask tech questions, post helpful info, or just read and learn.
brucie
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Posts: 56
Joined: Thu Oct 20, 2011 6:53 pm
Main scooter: vespa px mk1
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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
shipscat
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Main scooter: vnb1t
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brucie
registered user
Posts: 56
Joined: Thu Oct 20, 2011 6:53 pm
Main scooter: vespa px mk1
Contact:

Cheers but Seen that, its for a lammie rather than a Vespa, problem I have is blocking carb inlet off.
shipscat
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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
Davidsquaredson
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Posts: 225
Joined: Sun Jun 10, 2012 11:41 am
Main scooter: Early Eibar Jet 200
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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?
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carpe scooter diem

1974 Rally 200
1965 Li150
1963 TV175
1974 Eibar Jet200
holty
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Joined: Wed Jul 15, 2015 11:52 pm
Main scooter: lambretta gp
Location: east yorkshire
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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
Davidsquaredson
registered user
Posts: 225
Joined: Sun Jun 10, 2012 11:41 am
Main scooter: Early Eibar Jet 200
Contact:

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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carpe scooter diem

1974 Rally 200
1965 Li150
1963 TV175
1974 Eibar Jet200
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