Author Topic: KX250F crankcase pressure  (Read 4975 times)

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Offline SS109

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KX250F crankcase pressure
« on: August 21, 2018, 04:24:28 PM »
Working on a buddy's '04 KX250F and noticed there seems to be quite a bit of pressure in the bottom end. First time working on one of these particular bikes but adjusting the valves is easy enough. On reassembly the head of the timing plug snapped off. Didn't even get it to 20in-lbs (spec is 35in-lbs) and it snapped. Decided I wanted to make sure she would run ok so I figured I could live with a little oil coming out the timing hole just to fire it up. Anyway, I noticed a very strong pulse of compression coming out. It kind of stunned me that it did that.

Also noticed oil coming out the crankcase vent line but I've read this is a common occurrence with these bikes and he confirmed it has always done this. Odd but ok I guess. Seems like a lot of oil to me. I just thought with all that pressure in there it could be causing it even though the vent hose is routed properly over the intake manifold.

So, is this normal on a bike with about 26 hours since a complete rebuild?

« Last Edit: August 21, 2018, 04:48:08 PM by SS109 »
'90 KDX 200 (rebuild - DONE!) - '94 KDX 250 (soon to be a KDX250af)