vespa carb problem advice needed

[rbgaz]

hi all, got a px125 with a 166 kit on it, it had a 125 carb on it but it used to rev really hi after full throttle prob bout 4000 revs, so was told to put a 200 carb on which we have done but still the same, the tickover screw dos nothing at all, its fine if u pull the choke out a quarter, also fine if u undue the pilot jet so its lose, now is it the pilot jet to small or is it saying we have a air leak sil gone somewere, its new kit only done couple hundred miles

[cit205]

Sounds like an air leak ,could be main oil seal at worse. If you unscrew and take the clutch cover breather out then start the engine ,when it starts screaming by itself put your finger on the clutch breather hole ,if the revs settle down then it's the main seal needing replacing, because when they go they suck air in through the gearbox.
You may need to take the back wheel off and chock up the back end to do this.

If it's flywheel seal the tickover will tend to just be a bit fast and you'll get a flat spot on revving ,you can tell if it's that by taking the flywheel and stator off ,there will be oily fuel residue around there.

[ducksta]

could be your drive side oil seal gone

[roadrunnerian]

if it revs at 4000 on tick over i would say a air leak somewhere oil seal blown out, head not tightened,best of luck m8

[rbgaz]

if it is a seal would this be the reason the tickover screw dosnt do a thing

[cit205]

Yes any airleak caused by seal or otherwise ,such as head, carb seating. All the tickover screw does is hold the slide in a certain position to stop it closing right up so you are having that bypassed by the air rushing in somewhere else.
The air mixture screw on the back of the carb should be around 1.5-2.5 turns out but again if you have an airleak/seal gone that will get overwhelmed too.