250F KX250F Low Compression Problem

rdimon910

rdimon910

When I went riding last weekend my bike started up after a few kicks when it was cold. I stalled out in the woods and my bike wouldn't start for anything while it was hot. After I stalled, I tried to find TDC to start the bike again, but there was such little compression.

I waited for the bike to cool down, and I noticed that there was definitely more compression and it started up.

Anyone have an idea what's going on?
 
SRAD97750

SRAD97750

Moderator
Staff member
Whats the maintenance history?
When was the last valve clearance, and were you on the high or low end of the spec?
Did you have to adjust the valve clearance at the last valve clearance check?
How many hours ~ on the Piston/rings?
Do you have a decompression lever?
Was the ride a big elevation change?
-BIG DAN:thumb:
 
rdimon910

rdimon910

The bike has 65 hrs on it. I bought the bike maybe 6 months back used from a kid who claimed he just:

replaced the valves
replaced the piston rings.

When I got it, I replaced the cam chain because it was stretched. While I was doing that, I took the the top end off inspected the cylinder. There were a few scratches on the wall, but everything measured to spec.
The valve clearances were in spec too, so I left them alone. Yea there is a decompression lever. No major elevation change while I was riding.

Worste case scenario I'm thinking that the kid didn't replace the valves and they need to be redone and reseated.
 
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