air leak around intake area?

[specialized]

Hi fellas,

I've been trying to troubleshoot this issue for 4 days with no luck so far.

I was getting occasional hanging idle since I deleted my oil pump (was going faulty, leaking oil through airbox while sitting, + the tank used to take so much space, making working around the engine cumbersome), so I upjetted from 85 to 88 (I put like 20/25 ml oil per L fuel). Ever since, the hanging idle became way worse, hanging very high and basically never settling until turned off. So bad that when I release the throttle it keeps RPMs relatively high so I have to force them go lower by braking. This happens after the auto choke turns off and scooter reaches operating temp. Here's where the weird part comes from. I sprayed brake cleaner at the intake area where the gaskets are sitting (vid for context). The scooter turned off. I thought, fine, simple thing. Changed the gaskets with brand new ones - nope, same sh!t. So I thought just replace everything and get it over with, went and bought new reed valve housing and manifold (cheapest ones, but still brand new). After installing everything brand new, the scooter still turned off from spraying that area with brake cleaner. So I applied silicone gasket maker on both sides of each gasket, installed everything, tightened by hand only (as it should be 9nm by specs) and let it dry. Guess what - same story... Now, my roommate bought a cheap Aerox that was sitting 10years and rebuilt it for resale. I started it and sprayed in the same area, his scooter turned off too - LOL. The other weird angle is, brake cleaner, being a combustible substance, it'd make sense for it to raise RPMs rather than kill the scoot, or am I stupid?

The area where the case splits for accessing the crank seems totally fine, looks like there's hondabond sticking out of both ends.

A side note, while changing the reed housing I noticed that my piston is slightly scratched at the bottom part (img), idk if that could contribute to the hanging idle, but the scooter starts from 1-2 kicks so I guess compression would be fine.

[90GTVert]

Hanging idle could be as simple as lean idle mixture/pilot jet/needle setting. That said, with responding to spraying around the intake area I would do a proper leak test.

49ccscoot.proboards.com/thread/506/make-2t-leak-tester-ways

[johnv123]

Hey - I know it's been over two years, but did you ever solve this? My 50cc Minarelli does the same thing. Idle takes forever to come down and when I sprayed carb cleaner at the intake area (above where the reed valves are), the scoot shuts off. Is that supposed to happen? I'm swapping main jets and idle jets like crazy trying to chase this problem.