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My friend bought a 1987 trailboss 250 2 stroke and Won't start unless you choke it untill the fuel is running out of the carb. Once you get it started it wont run unless you have it half throttle or better. I have pulled the carb twice and cleaned it and have found it clean both times. It has fresh gas/oil mix. oil line not connected to the oil pump (don't believe it works) After reving the motor up letting it drop it will idle high for a moment and then die and you cant recover it without full choke again. I haven't checked the compression yet (waiting for the tester) I have a feeling it might have had a hot supper before he bought it. I'm curious if it could be a crank seal. Any ideas would be appreciated.

 

as to the hard starting i think you have a compression problem..and the high-rev doe sound like them FAMOUS crank seals.. the two 250"s i have were bought blown up and I boared the jugs .40 over and put wiesco pistons in..after getting them running they BOTH ran way lean due to crank-seals,the cluch side was the worst on both of them..after that learning experience they both ran great!!..if you have to tear her down i would sugest getting in contact with RICK RITTER from http://rittercycle.com/..if you want to add some go go he is the man to talk to when you are tearing it apart..

 

When you cleaned the carb did you pull the pilot jet out and get all the side holes and the main center hole clear?

 

Yes I pulled it apart completly both times

 

how do you fix lost compresion???

 

The first thing to check IMO is the rings.

 

thanks, will do been reading a how to rebuild two stroke page sounds pretty easy just gotta buy the bits huh. whats IMO??

 

In My Opinion.

 

Oops. Double post.

 

cool thanks jumbofrank.