'00yz426 low throttle misfire

4 replies to this topic
  • henrysdad

Posted July 11, 2004 - 05:50 PM


I just bought this bike a week ago.this is my street bike ,set up like supermoto. I searched the entire forum ,and found some useful info.Like the guy who has the same problem after installing the electrex wr ignition/lighting coil. I can't find that post(?!)again.I went thru the carb,It is all stock,as is the exhaust ,and the intake. It definately misfires at 1/8 throttle,any rpm,any gear. kind of random too,sometimes alot,sometimes not. it has an electrex light coil. I am begining to think this may be the problem. I tested everything the manual says to and everything is within spec. I hooked up my timing light to check idle rpm,and I watched the strobe,and at the throttle opening where this happens It is dropping spark. so now i feel it is electrical ,not jetting. I am getting confused. Has any one solved this problem?

  • Fastest1

Posted July 11, 2004 - 07:11 PM


I would suspect the CDI. The heat could be affecting it making it kind of random. Did you test it? Do you have one you could borrow from a friend? I probably have one in the garage if you need one. I run a wolf programmable so I really dont need the stock one. It is off of a 2000 also.

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  • henrysdad

Posted July 12, 2004 - 10:17 AM


I am thinking along those lines.I unplugged the tps today and the misfire almost is gone.And it started on the first kick,never was able to do that before .But it feels different,seems louder out the exhaust, and it backfires insanely on deacceleration.I have not tested the cdi ,that was the only thing I did not do..Unfortunately I do not know of anyone I can borrow from.If I come up with any funny readings ,I'll take that one from you.Thanks

  • henrysdad

Posted July 25, 2004 - 04:05 AM


I am still confused. I purchased a new CDI(not used/$26 ebay). that did not fix the problem.

If I unplug the TPS the misfire goes away.The TPS measures in spec, at the limits though.I cannot set it to the numbers in the manual ,it does not adjust enough.It is extra loud out the exhaust,when unplugged.

The lighting coil/stator are nowhere near spec for the stock magnito coils.

I talked to some racers at the local dirttrack event, all suggested richer pilot jet/different neddle. I will try that.still seems electrical to me. Any other thoughts?

  • bushy

Posted July 25, 2004 - 04:13 AM


Popping on decell is caused by a lean condition. 1/8 throttle is in the pilot jet range, so I guess they are right! :thumbsup:

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