XT 600 backfire

7 replies to this topic
  • arl27561

Posted 19 June 2007 - 11:09 AM


I have an 89 XT600 that runs real good when I roll the throttle on, but sputters and backfires through the exhaust when I let off the throttle. What might cause this?

  • maim

Posted 19 June 2007 - 05:56 PM


lean pilot jet is most common cause. mine does the same.

  • LLpeteJ

Posted 21 June 2007 - 05:48 PM


also.. spark plug wire or your typical bad xt600 cdi. when i had my xt i had to replace the cdi. i bought a aftermarket brand one on ebay for about $120 from the land down under. it was a very bad back fire. google xt600 cdi and see if the problems fit your problems

  • junkyard dog

Posted 22 June 2007 - 12:11 AM


Have seen exhaust leak cause same symptoms...

  • hawaii500_1999

Posted 22 June 2007 - 07:50 PM


you check your valve clearance?

  • foudkirk

Posted 26 October 2008 - 10:20 AM


MY 1989 xt600 had a clogged pilot jet that caused it to run lean and backfire.

Does any one know what is a good setting for the pilot jet screw?

he yamaha manual doesn't say as it come set & the access plugged off for emissions purposes.

  • treehopper

Posted 26 October 2008 - 01:52 PM


I have an 89 XT600 that runs real good when I roll the throttle on, ...

How could the pilot be plugged if it runs good? My vote is for an exhaust leak, and I would look first at the gasket wkere the pipe joins the cylinder.

  • boomerx7

Posted 19 March 2009 - 07:33 AM


i have a 1985 xt 600 just battled for two days found the coast enrinching valve diaphram was leaking vaccum by it sealed it up runs like a champ its the two screws on the left side of real carb has line over top to the secondary carb if it dont get vaccum runs like poop huffs through intake pops through exaust runs hot hope this helps thanks


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