400 lost all compression and dont know why

3 replies to this topic
  • Fatbunker

Posted April 08, 2008 - 07:26 PM


Just thought I would post up a topic. Last weekend me my brother and uncle were running a dessert race. When we got back he said his bike had died which is a 99 400. The story goes that the bike was running great and pulling hard. He stoped at the pit area for a check in. After that he started heading up a hill and heard a squeek and the bike died. It then restarted and then made another squeek and died again. This time it would not restart. The bike still barks on the 3rd or 4th kick but does not have compression most of the time. Could this be a problem with the compression release or is this something to do with valves. He is going to tear into it this week, but any help in advance is great. thanks for reading.

  • Fabwiz

Posted April 08, 2008 - 07:36 PM


Take a compression check, the squeek sounds kinda scary. Any oil loss?? Drain the oil and look for chunks.

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  • BASSic

Posted April 09, 2008 - 10:08 AM


Last weekend me my brother and uncle were running a dessert race.

Cool! I've always wanted to ride on a big pile of ice cream! :thumbsup:

Just kidding. Realistically, it's hard to say exactly what the problem is based on the description. Pull the top cover off the engine and that'll be a good start - check that the compression release is working properly, check that it hasn't jumped time or the cam gear hasn't rotated on the cam itself. If all of that seems OK, keep digging deeper to see what is going on.

  • Fatbunker

Posted April 09, 2008 - 08:49 PM


yea i like the big rock candy mountain race, thanks for the help guys he is going to try the tips tonight

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