Scooterotica

vespa t5 standard 125....owned by mate, when I open the throttle from 5000rpm onwards it pops and holds back !!! What do you think the problem is?

dirt or water in the carb possibly ?

it did it on mine, when i de exelerated then opened the throttle it would bog then pop. i down jetted and it was ok.

not sure if this is the same, i cant visualise whats going on to cause the pop

I'd check your compression ratio.... then let me know. (lol)

Could be fuel or carb but sounds as though it could be electrical. As such, I'd do all the usual Lambretta electronic ignition check; loom green off stator, etc. Try a different plug. Then I'd try sticking something up the tailpipe to try to clear any obstructions. Still no joy, I'd look to swap out the stator for another known good one.

Other than that... I'm completely lost with those funny V' things (no I don't mean anything rude!).

Good luck,

Adam

the way it feels (not talking rude here adam) is that on de exeleration its still sucking but with the carb shut i wondered if it was drawing gearbox oil or two stroke oil in then the bog could be it hydrolicing then the pop is the exhaust port dumping the compressed oil........i think ive invented the diesel engine lml will have that design off me im sure.

this particular engine has just been rebuilt (not by me or it would be half finished like kylies )

ive had the popping on every t5 ive had, got rid of it but dont know quite how. now i know its not me as ive not laid a hand on this one.