Real Fast Idle on66cc

Discussion in '2-Stroke Engines' started by Apachekid, Mar 9, 2010.

  1. Apachekid

    Apachekid Member

    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?
     

  2. Hawaii_Ed

    Hawaii_Ed Member

    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.
     
  3. Apachekid

    Apachekid Member

    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
     
  4. Hawaii_Ed

    Hawaii_Ed Member

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

    Apachekid Member

    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???
     
  6. Apachekid

    Apachekid Member

    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
     
  7. TOTAL CARNAGE

    TOTAL CARNAGE Member

    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.
     
  8. Apachekid

    Apachekid Member

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

    happycheapskate Active Member

    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.)
     
  10. Apachekid

    Apachekid Member

    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
     
  11. happycheapskate

    happycheapskate Active Member

    http://www.motoredbikes.com/album.php?albumid=860
    [​IMG]
    Its a $3 off brand replacement muffler for a 5hp Briggs vertical shaft lawnmower.
    It bolted right up with the stock gasket and $1 worth of replacement bolts. (use locktite!)
    Well, I did have to peen the back of it a little to clear the fins.

    I will check to see if the gasket has gone bad. But it idled higher than many HT's from the first run (only used this muffler since build).
    I've taken it off once to survey the inside of the engine after break in (all good). The gasket was ok. I think Sick has some better ones. Probably a lawn mower shop will have them too, but you will have to hollow out the cavity more with an Exacto blade.

    You are probably talking about the 1/2" pipe thread screw on round mufflers. Those are cool, but I don't know if any bolt on with the briggs 2 bolt pattern. Scooter stores have the Xchamber things and scooter mufflers (boxes) even that can take a stock muffler bolted to the exit port.
     
    Last edited: Mar 11, 2010
  12. Apachekid

    Apachekid Member

    Amazing!:tt1: Very nice looking bike there, Happy..You did a great job!
     
  13. happycheapskate

    happycheapskate Active Member

    Thank you. Its my latest hobby. I can't leave it alone. I drive it to work all the sunny days, and most folks love it. The kids at the Sonic come out to ogle it and make me rev it up. People at stop lights want me to do burnouts but I tell them its too high geared for that. It only goes 32, but will climb hills in mud at just above 9mph without stalling or shuddering.

    I put the Maxpower muffler on it because the stock Black Cat wouldn't fit the wide frame, and I broke it trying to heat it up and bend it. hahaha. It sounds like a McCullough chainsaw. RRRRRRRUN NUN UN UN UN UN UN.
     
  14. Apachekid

    Apachekid Member

    I gotch there, HC...32 is **** good speed..I could get up to 35 with the xchamber..dont want to go that fast very long anyway..You're right at a light they all want you to burn out..I just pedal away and pop the clutch..pedalling gets me going fast pretty quick...36T spkt good choice!
     
  15. happycheapskate

    happycheapskate Active Member

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