Can't quite get the jetting right on the XR600

5 replies to this topic
  • pd10913

Posted June 28, 2007 - 10:56 AM


I have made a few mods to my 98' Xr600, ie FMF Powercore 4 pipe, snorkel removed etc and I've tried various jet setups and at the moment the 158/68 seems to work pretty well but when your let off the gas it hesitates and continues revving for a second before dropping down.

Does this mean the mj might be a bit too big?

  • Kawabuggy

Posted June 28, 2007 - 11:01 AM


I am currently running the same set-up-68S pilot & 158MJ, and before I lost 4th gear-the jetting seemed to be perfect. I am going to step up to a 160 MJ after I repair the trans just to see what happens. Where is your needle set-which clip position? What type of air cleaner?

  • pd10913

Posted June 28, 2007 - 11:13 AM


needle in 3rd clip and stock air filter.

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  • cleonard

Posted June 28, 2007 - 03:55 PM


Does this mean the mj might be a bit too big?

Yes, this usually is what it means. Try a 155 and see of it helps any. Get a jet from the same mfg as made the 158 that you have now. There can be differences between jets with the same number, but from different mfgs.

  • FZ1426

Posted June 28, 2007 - 07:50 PM


You have to get rid of the stock filter and backfire screen as well.

  • Kawabuggy

Posted June 29, 2007 - 05:33 AM


I would say to change the air filter BEFORE you change the jet again! If it is running just a tad rich right now, going with a UNI filter will lean it out a little bit.

Purchase/install a UNI air filter, then see if the problem goes away. I have the UNI, and with the same MJ, I am NOT rich. My spark plug after a full throttle run is a nice caramel color.

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