Idle's great! But lacks power..

Discussion in 'Motorized Bicycle Trouble Shooting' started by Jonathan Christianson, Feb 11, 2018.

  1. Jonathan Christianson

    Joined:
    Feb 11, 2018
    Messages:
    2
    Likes Received:
    0
    I dunno where to start. But I have two bicycles. The first one I own is a huffy beach cruiser. Runs perfectly fine. My second bike is a bayside cruiser, however. Isn't running fine. It idles Great and revs not great. But compared to my first bike, that thing revs to the moon. Reason why I'm building another bike is that I'm putting a jackshaft shifter kit on this bike, Just so I can start from a stop. But one issue. This new engine I purchased has little to no power. Tops I can go is about 15mph on level ground. I tried swapping carbs and nothing changes. It's not the oil mix ratio. I tried both 16:1 and 20:1. Nothing varies. I know it's not the carbs. I checked the piston to make sure the arrow was pointing to the exhaust port. The head is torqued down good. I don't know what it is. But what I'm thinking, it's probably either a spark related thing. Or exhaust. Or just the engine itself is junk.

    Tomorrow I'm gonna swap the magneeto and the cdi/spark plug to see if I get any difference
     
    #1 Jonathan Christianson, Feb 11, 2018
    Last edited: Feb 12, 2018
  2. crassius

    crassius Well-Known Member

    Joined:
    Sep 30, 2012
    Messages:
    3,843
    Likes Received:
    104
    checking arrow on piston does nothing for you - it is the locating pins for the rings that have to be back near the intake port

    if intake pipe is steel, there may be a bit of chrome sticking up on the end where carb fits - filing right along that edge at 45 degree angle will fix it

    if you got an older style motor, it will sometimes take quite a few miles to run in
     
  3. Jonathan Christianson

    Joined:
    Feb 11, 2018
    Messages:
    2
    Likes Received:
    0

    I'll look again. But I didn't see any metal in there earlier.
     
  4. crassius

    crassius Well-Known Member

    Joined:
    Sep 30, 2012
    Messages:
    3,843
    Likes Received:
    104
    rare that one can see it, but lightly sliding a finger off the end allows it to be felt - if there it can cause a slight air-leak that doesn't raise RPMs but robs a bit of power
     
  5. 4banger

    4banger New Member

    Joined:
    Mar 9, 2018
    Messages:
    8
    Likes Received:
    0
    I'm having similar issue with my huasheng 4stroke stock with 44t pinapple rear sprocket. Old one was great, hit about 33-36mph slight knocking once in a while. New kit won't clear 22mph but runs smooth. Would like to hit 30 again though. First everything ,bike and all kit setup is the same, but the new hs transfer case was a dual chain from bike berry. The old one was a single chain, didn't think it would make that big a difference. I got a flex poopoo exhaust and 40t rear hub sprocket, only increased from 20mph to the now 22 mph Max. Do the engine vary that much? Could it be just the dual chain trans vs the single. Any help to what would cause that 10-15 mph difference would be great?
     
    #5 4banger, Mar 9, 2018
    Last edited: Mar 9, 2018
  6. Tyler6357

    Tyler6357 Active Member

    Joined:
    Mar 15, 2012
    Messages:
    916
    Likes Received:
    32
    Idle revving? no power? Sounds like an air leak causing loss of compression. Check for any air leaks around the head gasket, intake, and carb connections. Also check your seals for any leaks.
     
  7. crassius

    crassius Well-Known Member

    Joined:
    Sep 30, 2012
    Messages:
    3,843
    Likes Received:
    104
    it's a 4-stroke, no seals

    might just be the governor some motors have now
     

Share This Page