wr400 problem

a friend of mine was riding his wr400 wide open, 5th gear, and the bike quit on him. Now he can push the kickstart without using the decompression lever.

what exactly happened, and what can be done to fix it?


Offhand, I'd say he lost compression! Ha Ha. Need a lot more information before I can offer a suggestion.

I agree, you obiously have no compression now, rings, valves, cams, piston hole, compression plug blown out. It could be a lot of things, give us some more info so we can help.

I just went out and had a look at the bike, and as predicted, no compression.

i kicked it over 2x, and then it caught on something, and now it wont go over at all - so my guess is something is broken inside and its caught now.

all i know is that he was riding the bike wide open - my guess is that he over-revved the bike.

sounds like valve, cam or piston isses.... You might be able to pull the valve cover and inspect the cams and their operations to see if it can narrow it down a little. If you kicked it over 2x and it all the sudden caught, it could be a valve stuck open causing no compression and a stop in the rotation. Pulling the valvecover and hopefully getting it to turn over forward or backwards should narrow down the head being bad. It might sound stupid but pull the plug and try to kick it over again. Drain the oil and pull the oil filter out and inspect it, this usually will answer your question if you know what to look for, is there water in the oil, shavings, chunks of metal, pieces of rings, does it stink real bad, ??? my early say would be a valve issue or aburnt up piston.... I know you probley dont want to hear that and I hope Im wrong!!!!!!! :thumbsup: More info please!!

I have seen bikes go pop more than once during high speed, wide open in high gear. Just have the checkbook handy, its going to be expensive, no matter what.

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