2 stroke RPMs HT engine

Discussion in '2-Stroke Engines' started by Frankfort MB's, Apr 4, 2016.

  1. Frankfort MB's

    Frankfort MB's Well-Known Member

    I was going for a ride the other day and with a heavily ported and port matched 66/80cc engine from gasbike.net... I've built several of these MB's but none modified this way and this bike I was able to get up to 33mph and it was still climbing but that little 2 stroke was hitting the major RPMs so I backed off.... This bike does have 44 tooth sprocket, I also have a 41 I thought about putting on it since some of the guys near me tend to have drag races lol...
     

  2. Frankfort MB's

    Frankfort MB's Well-Known Member

    How many RPMs can these motors handle before I blow another one up from my fun times ;) lol
     
  3. butre

    butre Well-Known Member

    the stock bearings won't grenade straight away until you hit about 10 grand, but anything over 8 will wear them out excessively quickly. the big end bearing and the mains don't tend to blow from rpm in my experience so they can be left stock. I've run all the way up to 12000 rpm with a bushing in place of the stock small end bearing.
     
  4. Frankfort MB's

    Frankfort MB's Well-Known Member

    Lol I might want to use that 41 tooth before I blow the bearings or just don't go 33mph on a bicycle
     
  5. butre

    butre Well-Known Member

    33 is perfectly fine on a stock engine with a 44 tooth rear. you're only spinning around 7700 RPM. I know a guy with a stock motor that spins around 9100, and current daily driven bike spins at 10,500 with a 36 tooth
     
  6. Frankfort MB's

    Frankfort MB's Well-Known Member

    With being ported would it be able to hit higher RPMs? Or is it just adjusting the powerband to the top end
     
  7. butre

    butre Well-Known Member

    depends on how you port it. crank balance is crucial too, I've seen as much as an eighth inch runoff on the cranks
     
  8. Frankfort MB's

    Frankfort MB's Well-Known Member

    I try to make small bounds at a time I went threw 2 sets of rings after putting the cylinder back on... Just wasn't paying attention to both sides.... 20$ and 2 weeks later i finally got it on
     
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