99 wr400 lost compression, now wont start at all


3 replies to this topic
  • brileyb

Posted August 29, 2011 - 04:07 PM

#1

this is the story. about a week ago i was riding with some friends and the bike was running great. came out next day about to go riding again and it lost alot of compression. i figured i would try to start it, so i did and it ran ok. rode it around a little and it was fine. went for a ride yesterday and it started first kick like always when it was cold. then it started not wanting to start at all unless i bump started it. then we all stopped to take a break and my bike wouldent start at all tried bump starting it, nothing. ended up having to get towed out of the woods by a 4 wheeler. :) anybody know what could be wrong or has anybody else had this happen to them? any help would be greatly apreciated. thanks

  • miweber929

Posted August 30, 2011 - 03:57 AM

#2

When is the last time you checked valves? Sounds like too tight intake valve to me.

When a bike looses compression, that's a bad thing. Continuing to ride even when you know something major is wrong (like low compression) is asking for large repair bills and substantial engine damage.

Mike

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  • brileyb

Posted August 30, 2011 - 05:00 PM

#3

i just checked the valves a couple weeks ago and they all were in spec. could the head being a little loose cause it to loose compression but still run for a while? before this problem it ran great started first kick hot or cold.

  • anoldsman

Posted September 02, 2011 - 07:00 AM

#4

I bought a friend’s 1998 WR400 because of the same problem. He said that it was running fine one day and then nothing. I checked the lash and it was good so I pulled the cylinder and piston. The second ring was stuck in the ring land causing massive blow by and no compression. Since it was torn apart I decided to replace the piston, rings, and gaskets. It now runs like new. Well new to me at least.




 
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