Engine Trouble newby with power loss prob

Discussion in '2-Stroke Engines' started by swamprat, Mar 31, 2013.

  1. swamprat

    swamprat New Member

    this is my first venture with a motorized bike but not with 2 stroke engines as have been playing and racing outboard hydroplanes since the '70's but i'm getting old.....er.....and decided to put a motor on my bike. now that i have it broke in i went for some speed spurts. the prob is that it runs ok [all china crapynes conciderd] for about a minute or so then it suddenly slows way down. in the outboard engines [2 stroke] this means to lean most of the time. so i played with the needle. no good. i opened up the jet a little bit. motor lost some power and speed but no affect on the main prob. before i get all wrenchy or throw the thing in the lake i thought i would run it past you guys. btw this only happens at full throttle.

  2. crassius

    crassius Well-Known Member

    I've seen this with too much vibration causing the fuel to foam in the bowl. Are you seeing a lot of bubbles in the fuel line?
  3. swamprat

    swamprat New Member

    haven't looked at the feul line but omg does the thing viberate at top rpm. will check it out now. back in a few
  4. swamprat

    swamprat New Member

    sure enough. bubbles
  5. swamprat

    swamprat New Member

    geeze! just wanted to ride the thing awile before tore it down and blueprinted and modded it. after all stock is for no fun. lol
  6. crassius

    crassius Well-Known Member

    you didn't mention if you had finished running in the engine yet - for the first couple hundred miles you shouldn't go much over 1/2 to 3/4 throttle - later, the engine will smooth out quite a bit

    for now, check that the engine is mounted tight to the frame, as that will dampen some vibration & check that intake & carb are tight
  7. swamprat

    swamprat New Member

    im at the end of the break in period where i can open it up for spurts. that's when the prob showed up. i checked the engine mounts and they where loose. i also need a o-ring for the carb. there are several upgrades i would like to do to make it reliable. more power comes later after other motor projects.
  8. StrontiumEthics

    StrontiumEthics Motored Bikes Sponsor

    Loss of power usually indicative of air leak.
    Check the head and make sure its torqued down look for ANY kind of leak. I had this happen before also.
    Make sure your carburetor float adjusters actuate to prevent Carb overflow
    Tighten All bolts especially around intake.
    Definitely do a spark plug test to see what your mixture looks like! (Post pictures if you can)
  9. geebt48cc

    geebt48cc Member

    Yeah, sounds like the o-ring could be one of the answers. Also, keep head torqued too...............(all nuts and bolts for that matter)
  10. rawly old

    rawly old Member

    My advice, unless you enjoy having to constantly tweak
    your engine, spend the extra money and get a Tanaka PF
    4000. the 7 yr. private use warranty sez it all. If you want
    performance & reliability don't waste your money on cheap
    garbage. I've been through a lot of engines and I know
    whereof I speak.