idle

[sctrdawg]

:help: :swear: :censored: i have a Qmb 139 Gy6 fourstroke with a 20mm cvk carb. i have completely cleaned the carb inside and out ,adjusted the air/fuel mixture and it still idles at around 3500 to4500 rpms the idle the carb makes no difference as it is set at the lowest possible setting (it isnt even touching the butterfly mechanism) HELP! dont want to fry the clutch!

[lshigham]

Is your cable sticking? Have you checked the tensioner?

[sctrdawg]

all that is good! i cannot for the life of me , understand why it is doing this!

[sctrdawg]

the throttle snaps back fine so i know the butterfly is closing. what would cause this!

[sctrdawg]

could a vacuum line leak cause this?

[90GTVert]

I'd definitely check for vacuum leaks around the carb and intake and be sure there's enough slack in the cable to let it idle lower.

[sctrdawg]

will do!

[Fox]

yeah a vacuum leak could be the culprit but I'm curious since a 20mm carb is larger than the stock carb I'm wondering if you have changed anything else like the air filter per chance?

If you still have the old stock carb try installing the old idle jet into the new carb. Or, is the throttle cable too taught maybe and needs to be adjusted?

[dude]

Some intake dry out and crack or tear. Spray for leaks.

[sctrdawg]

aftermarket air cleaner, rejetted dont know what size did it with a sewing needle. it was running great for a few mnths after i did it. idles around 4500 on centerstand, around 3000 - 3200 on the ground. im seriously baffled my needle is set to the leanest possibe setting ,richening doesn't change anything except how hight it revs and less power. this thing screams on take off . top speed arnd 45 now, when i got it brand new sept '09 ,it ran52 mph strait off the showroom floor

[Fox]

Cracked intake or some other vacuum leak as you previously suspected would be the #1 suspect on my note pad. If you spray some carb cleaner on the intake boot while it's running and there's a change in the engine's sound then there's gotta be a vacuum leak there but it could be a craked vacuum line elsewhere. If you have any emission control devices on there I would suggest removing/plugging them off. It makes for less clutter. You don't need any o' that crap.

[sctrdawg]

yeah Fox gnna try that today! thanx!