Anyone know about the ignition timing on the yami's

4 replies to this topic
  • treukauf

Posted October 13, 2005 - 12:49 PM


I was wondering what the stock timing ( after cutting grey wire) is like on these bikes. They are running a ton of compression(but big cam to bleed of a little at low rpms) so wouldnt the timing be pretty conservative to allow them to run on pump gas? I was considering running race gas and advancing the timing. I'm not sure if anyone out there even makes a new cdi thats advanced, but it seems that a lot of potential is left in that motor. Or is the yami head just so efficient it can run good timing and still not detonate on pump gas? I'm just trying to squeeze some ponies out of my 00 wr400. Any knowledge on this out there. Thanks

  • dominator426

Posted October 13, 2005 - 06:10 PM


I actually tried backing off the ignition timing to allow mine to run on 91 pump gas by slotting the ignition pickup coil. It made it run poorly so I mix with 1/3 Av gas...

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  • dirtysouth

Posted October 13, 2005 - 06:16 PM


Been reading up and looks like all of that power you want can be found by retarding the exhaust timing about 20 degrees or put simply... dropping in a YZ exhaust cam. That, the jetting, and the grey wire (which retards the ignition over 5000 revs or something) seems to be the only real diffs in the motors. :banghead:

  • treukauf

Posted October 14, 2005 - 09:16 AM


dominator why did you retard the ignition timing? Did you do head or piston mods ro raise compression as the bikes are already designed to run on 91 octane. As rpms increase the ignition must be advanced to give the explosion more time to occur since the power stroke is shorter. Retarding the timing would cause a loss of power at high rpms. I thought I've seen some crf's with aftermarked computer boxes on em. I just thought if I ran some vp 140 and got an after market box I could pick up some ponies. Dirty south, the 400's ran the same cams (yz and wr) The wr exhaust cam was just indexed differently.( The connecting rod and piston are slightly beefier on the wr)

  • treukauf

Posted October 17, 2005 - 05:12 PM


any one else have any info on this subject?


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