auto decomp. not working correctly

2 replies to this topic
  • jake27

Posted April 03, 2005 - 09:21 AM


I just did a complete rebuild on my yz426, new valves,head,cylinder(440 big bore), stock compression piston etc. Last year I had a major engine meltdown and it ruined everything.I have both Hot Cams auto decompression exhaust and there intake cam as well.The bike is timed right because I can bump start the bike and it runs excellent, but when I try to kickstart it, it kicks over like a bear and will not start because I can't get a good full kick. Anyone have any ideas on what might be wrong? I would appreciate any help thanks,Matt

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  • 02YZ426

Posted April 03, 2005 - 09:29 AM


Did you shim the exhaust cam properly? If the valves set too loose, then the pin in the decomp cam wont open the valve far enough to release the compression while kicking it over.

  • jake27

Posted April 03, 2005 - 12:02 PM


I do have it set a bit on the loose side because of having new valves . I'll have to run it quite awhile and see if the valves work in, if not i'll have to re-shim it. That makes alot of sense, thanks for the input,Matt.

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