welll our 400 scrambler broke down thsi weekend and my little mighty 250 pulled it 5 miles back to the trailer[img]i/expressions/face-icon-small-smile.gif[/img] and we were just taking it apart and did a compression check and its only coming out at 23!?!??! which i no has to be really bad and wen i looked at the top of hte piston it has a lil burn indent but not a hole...also before it shut down my father said it made some real loud pings then just shut off and wouldnt start again and the plug was reallllly grey which i also no is bad. can someone tell me what they think it is?? im thinkin maybe the rings went and the piston has some damage too and def rebuild??

 

it also backfires when u try to start it witht the electric start

 

looks like it was lean sounds like the piston skirt is broke to that was kinda like my 400 when i got it off my buddy

 

well since im gonna have to take it apart u have to drain the coolant first right?? if u do then how?? thanks

 

un hook it at the bottom of the motor at the lowest point..and let it drain

 

THere is a drain on the bottom of the radiator.

 

we got it apart actually the reason it did this was partly due to the coolant wasnt pumping through the system?? and it ran wayy lean and burnt a hole through the cylinder wall!!! becasue the coolant wasnt flowing throught the cylinder walls

 

ouch sounds like u might have to sleeve it that sucks

 

Wow sorry to hear that. I have been there, and did not like it....but I just burnt a hole in the piston.