Real Fast Idle on66cc

[Apachekid]

Anyone ever had real fast idle on start up, with choke on or with it off?..then idles down after 2-3 minutes when it gets to operating temp. (After runnin a couple blocks) Then idles fine all day..I sprayed everywhere for air leak, tightened head bolts, intake bolts. Cant get rid of really fast idle at startup...throttle has slack and acts good every day.Cant think of anything else...Any ideas?

 

[Hawaii_Ed]

I'd say air leak at the carb...can put an O-ring in the base where it slide in, or people have cut a tin can and slid it under the clamp to seal the gaps. has to be an air leak somewhere.

 

[Apachekid]

Exactly what Im thinking, Ed. I got an O ring seal on carb inlet, but I never had one on top cap of carb. I think Ill stick one up there, but Im still thinking the slots in the carb inlet

 

[Hawaii_Ed]

wrapping the can around the slots has helped some people. have you checked the intake gasket? The cheap ones burn out over time.

 

[Apachekid]

Yea, replaced it with good one last week..dont think its there. really hard to tell if Im sealing good on O ring when I push carb on...what about using gasket sealant there instead of tin can???

 

[Apachekid]

Ok, took carb off today,filed off intake weld, so carb bottoms out on O ring, sealed with small amt. sealant, tightened down clamp and intake bolts...already put good gasket on...checked throttle slide assbly and cable has slack. top cap threaded correctly, Bike still idles high at start up...then when it gets to operating temp, it idles down and runs beautiful after that. still think I got an air leak but dont know where to look. Ive replaced the head gasket, but not bottom cylinder gasket..Also I never put an O ring in top cap on carb, Anyone put one there? Anyone else heard of startup like that? Cant figure it out.......Cheers, Apache

 

[TOTAL CARNAGE]

This is a long shot but check the needle in the slide. Make sure the adjustment clip is under the washer.
I had an engine that acted that way ( but any time, not just cold) it would idle fine one time and fast the next and that was the problem.

 

[Apachekid]

Just reassembled carb slide assmbly. needle clip in slide, then retaining clip, then spring, then top cap..real careful to keep slots aligned. i'll ride her tomorrow..thanks for tip Carnage,:sometimes I hit longshots.....later

 

[happycheapskate]

I'm running a Grubee 48cc skyhawk with a lawnmower muffler (very little backpressure, large boxy area to exhaust into).
It runs nicely with surprising low rpm power, but idles quite high sometimes when the bike starts up.

I think its the float or related needle valve in the carb bowl. The instructions warned that these are easily bent by shipping mishandling, and can be bent to alter the operation.

I think that would explain too why sometimes it does it and sometimes not, and sometimes the bike will leak fuel when parked outside, and sometimes not. ( I use the petcok when parking inside buildings.)

 

[Apachekid]

Hey, HappyC ...Im running 66cc Grubee with a lawnmower muffler on the end of my expansion chamber...Been on for 2 or 3 months..Took it off today, another blown exhaust gasket and stuck the stock pipe back on..PRESTO! No more high idle..Probably the big chunk of missing gasket sucking air big time..think Ill run stock pipe for awhile...a lot less noise!! Still have my top end, but less torque in midrange. I like the X Chamb, but that lawnmower muffler not cutting it. You running XChamb on your 48cc? what kind of lawnmower muff? mine was off Briggs/Straton.........Apache