two stroke won't rev

Discussion in '2-Stroke Engines' started by steve mck, Mar 22, 2009.

  1. steve mck

    steve mck New Member

    I have a 1973 yamaha gt 80 that runs and idiles but will not rev above about 3 grand i have cleaned the carberator checked the points gap checcked the exahst for carbon build up it has great compression doues any one have any ideas what could be wrong?



    HERPER Member

    i had the same issue a little while ago... and i am still trying to get all the kinks out... but i found out my CDI was busted. i replaced it and fired up and idled and ran.
  3. steve mck

    steve mck New Member

    It has ecelant spark and as far as gasflow i, rebuilt and cleand carb tank and filter
  4. steve mck

    steve mck New Member

    NO cdi box this is 1973 points ignition
  5. steve mck

    steve mck New Member

    i purchased it like this
  6. cooltoy

    cooltoy Member

    My first reaction was the condenser, an often overlooked part on them old points engines.
  7. duivendyk

    duivendyk Guest

    Does it refuse to rev onder any condition or only under load,does it cut out at high speed or just has no getup&go.Cutting out is usually a defective plug.what does the plug look like,normal,oily or carbon fouled?.Replace it any way.What's your oil ratio.Ignition can fail under compression pressure (it takes much higher voltage to fire plug at WOT than at idle or under light load)
  8. steve mck

    steve mck New Member

    Sorry about not resonding right away been busy ..With flooding and winter storms up here in Grand forks ND.Any way back to the subject at hand i picked up the bike after it sat 25 years in the corner of a guys garage And after doing the work describe above it starts right up one kick idles good just wont rev it still up on a lift so it hasn'tbeen put under load yet may be ill try a condser after hearing from yous

    Thanx steve