new member. long time motorised bike user. need help

Discussion in 'Introduce Yourself' started by bikedownunder, Feb 16, 2013.

  1. bikedownunder

    bikedownunder New Member

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    Hi there,
    Have been lurking these forums for months and finally decided to make an account as i cant seem to find a solution to my problem even though there are hundreds of threads about it.

    I have two 66/80cc bikes. Recently my newer bike (about 250km on the engine) has started stalling when idoling. I know what your thinking (oh great, another idiot who cant read forums) however i have been riding motorised bikes for years and have had many problems in the past. It first started stalling when my killwsitch wires melted onto the exhaust forming a circuit and killing the bike instantly. I replaced the wiring and all was well again but now was stalling on idol. Played around with the idol screw and no luck. I can be riding and disengage the clutch and it will rev up to about 3500-4000 and then drop slowly until stall but if i have idol screw further out it stalls instantly when clutch is disengaged. So replaced killswitch and throttle, no luck. Tried all the usual suspects, spark plug was the right colour but replaced plug and module. Replaced carb incase of hairline cracks that i couldnt see and sealed it as usual. Fresh fuel mixed at 26:1and even added a breather to the tank cap. Cleaned guck out of exhaust and cleaned baffles. Float is at the same level as my chopper with same engine and carb. Any suggestions guys? :-||
     
  2. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    It sounds kind of like an air leak. Maybe a very small one. Crank seals leaking?

    I'd definitely go to 40:1, not that it will help this problem.
     
  3. Huffydavidson

    Huffydavidson STREETRACER/MANUFACTURER

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    Change your mix to 32:1 and run 93 octane gas. If that doesn't work try rejeting. Good luck.
     
  4. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    93 octane doesn't do anything but cost more. Our bikes have about 5:1 compression.
     
  5. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Plus his problem came from something changing....like an air leak. Re-jetting may mask the problem if it's a small air leak, but it won't fix it.
     
  6. LabRat

    LabRat New Member

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    Ive had this happen and tracked it to clogged in tank fuel filter on the petcock
     
  7. LabRat

    LabRat New Member

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    Q: could an air loc cause this if the tank didnt vent?
     
  8. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    I would think it would just crap out at speed if that were the issue. The engine uses so much more at speed than at idle.
     
  9. Huffydavidson

    Huffydavidson STREETRACER/MANUFACTURER

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    yeah you're right you guys running 5 and a half to 1 well I'm running a race motor which is 12.5 to 1 in 160 pounds so octane is everything to me .and I only run AMSOIL the best synthetic out there !!!!!!
     
  10. 2door

    2door Moderator
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    I concur. What you have is the classic symptoms of excess air entering somewhere it isn't supposed to. Intake manifold to cylinder gasket, carburetor to intake manifold, crankshaft seal.

    Tom
     
  11. fatdaddy

    fatdaddy New Member

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    Yup, I think 2door is right. An easy way to check, (if it will idle long enough, If not, set the idle up for a minute.) is to spray some water on the intake connections. A little water wont hurt the engine at all, and you will be able to tell immediately if there's a leak. It MIGHT kill the engine. At the very least you will detect a change in RPM's. I really dont know how you would check for air leaks at the crank seal.
    fatdaddy.
     
  12. bikedownunder

    bikedownunder New Member

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    Thanks a lot guys. Have checked the manifold and carb connections and no leaks there. Im running 26:1 because im using non synthetic oil. I will take it into a moped shop today and get them to do a compression test to see if im losing on idol. Will keep you guys updated :)
     
  13. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    26:1 is way too much oil, even with non-synthetic.
     
  14. 2door

    2door Moderator
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    A "compression test" isn't going to tell you if there's an air (vacuum) leak.

    If you're certain the carburetor or intake manifold isn't the problem then you need to concentrate on the two crankshaft seals. I also agree that you need to reduce your oil content. Go to a 32:1 or 40:1 mix. Your engine will like you for it.

    Tom
     

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