sporadic compression

7 replies to this topic
  • funktree

Posted August 26, 2001 - 02:11 PM


What are possible causes of sporadic compression? Is there anything that could cause it besides the comp. release?

  • jerry426

Posted August 26, 2001 - 02:51 PM


If you're talking about a MAJOR loss of compression (similar to using the compression release), I'd say it would likely be a valve intermittently sticking open or not fully seating for whatever reason.

Jerry in Deltona, FL

  • funktree

Posted August 26, 2001 - 04:40 PM


thats exactly what Im talkin about. Im gonna take it in to the local shop on tues. I worked on the damn thing for about 10 hours this weekend and still didnt get to ride.

  • freestyle111

Posted August 26, 2001 - 06:31 PM


make sure you check compression release cable.maybe its frayed or not lubed and not letting release close all the way.you might want to check to see if cable is routed wrong causing compression release to open when you turn bars.

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  • funktree

Posted August 27, 2001 - 10:28 AM


If I had any kind of valve problem then I would never have compression, and not have it go in and out??? Please tell me Im right

  • Mook

Posted August 27, 2001 - 02:12 PM


Originally posted by funktree:
If I had any kind of valve problem then I would never have compression, and not have it go in and out??? Please tell me Im right

I don't think anyone can say for sure, there are a lot of instances where a valve could stick, bad day at the factory - shavings, sticky cable - who knows.

I had the "cable routing" problem a while back, it was a simple oversight in my case where I was putting on my new (at the time) scotts 3-clamp and stabilizer with new bars and routed the comp release cable wrong and every time I turned one way the bike would cut off. It took me a while to realize what was happening and this would cause the valve to stick open also. so even with the bars straight again - no compression.

felt pretty stupid.

Actually I hope this is your problem, because then you will be riding soon. otherwise, well, you know...


  • freestyle111

Posted August 27, 2001 - 06:26 PM


wasnt there a compression release vavle problem with certain year yz and wr,s i thought i read a post or arcticle about it.

  • peterg.mangahao

Posted August 27, 2001 - 11:02 PM


Check under the Valve cover, I've heard of two bikes where the Decompression actuator had burred over where it touchs the valve, and consequently not releasing properly. especially if the decompressor is used with the engine running.
My 400 does it occasionaly, especially when it hasn't been used for a while. Tho it clears after a few kicks.

Pete Galpin
New Zealand
WR 400, Husky CR430


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