Hi.
I just bought an '01 KLR 250 that doesn't run. The guy said it had lost power over time. I really don't think he told me half the story. He had replaced one of the radiators at some point too.
On inspection I noticed it seemed to have 0 compression. I checked the valves and they were all tight - couldn't get a feeler guage in at all - so they were pretty much 'open' or about to open, making it really easy to turn over. I adjusted the valves, cleaned the carb and put in fresh gas. The bike felt much better with valves adjusted. I finally got it to fire up but it ran really poorly (almost sounded like a 2-stroke) and it was smoking. It would hardly take any gas - kept bogging. I was finally able to coax it up to a higher RPM with the throttle ...kinda let it 'build up'. I let it warm up some. After warm a little i revved it up pretty good a few times, then all of a sudden - caput! It just quit. I've messed w/ dirt bikes all my life - it wasnt enough to blow it.
When i tried to crank the bike again, i noticed it had 0 compresssion again. Even after waiting on it to cool down. I'm sure the valve clearance is back to 0, but i don't understand why or what could be wrong to cause that. I do believe it had gotten hot on him riding on the interstate and pushing the bike. It may have gotten hot on me i suppose?....but would that cause the the valves to 'tighten' all at once and not loosen up after cooling? Any help i can get is really appreciated!