Poorly px125

[Dazza]

A mate has been round with his vespa which has been struggling in the past few weeks.
It's a px125 and had been running fine,

It won't tick over well, always needs choke to start, won't rev cleanly ie you pull the throttle back and wait a few seconds for it to pick up then it seems to rev quite well, it doesn't settle down too well after either, it will either die or revs it's spuds off.

I took the carb off tonight and the air box, cleaned everything, a bit of sealant on the gaskets and refitted everything, but it stayed the same.

I adjusted the throttle stop to try and get a tickover but it wouldn't tick over with it fully wound in, the air screw was 1.5 times out and wouldn't make any difference if wound in or out.

It does have non standard size jets in but as I say it had run well before with the setup.

If it was flooding would it cause these problems?

Had to pack in tonight (didn't want to upset the neighbours) any pointers before we start again tomorrow night?

Edit.. Had another go tonight, adjusted timing- all ok, swapped cdi, played with carb again but still no joy.
I am starting to think the rings are to blame , doesn't seem to be a lot of compression - would this give the problems mentioned?
Another thought is maybe exhaust blocked?

Anyone any thoughts?

[elgarra]

I reckon you may be right about the rings.

[DazzerLancs]

I would say an oil seal is on its way out, you can check by dropping the engine oil and either looking for petrol in it or there may not be any oil in it, meaning its being dragged in through the seal. Is it smoking? It could also be the mixture screw.

[Mr Grog]

Try pulling the choke out and see if the engine runs better which will point to the main oil seal being suspect.

[Dazza]

There's no excessive smoke and there is hardly any difference when the choke is out either.

[sean brady scooters]

check that the pilot jet is not blocked...........

[Dazza]

I have, a couple of times now - to no avail, the lad who owns the scoot has ordered a set of rings, that will be another avenue explored..

[sean brady scooters]

then it probably is needle valve/tap jet.........

[Dazza]

Not getting enough fuel you mean?

Wouldn't that mean it would start ok because the bowl is full then struggle to pull more fuel - or am i being a feckwit?

[sean brady scooters]

sometimes they can stick open.............and flood

sometimes they can stick shut................and starve

sometimes they can even do both...................intermitantly.............weird but true.........
best to just replace with new................