Well, I haven't been here in awhile and need the forums help.

I have started to foul plugs om my 2000 Wr 400. I know what your going to ask and yes, I have done all the YZ mods and carb job and this has been done for over 1 1/2 years with no problems.

I remember problems with CDI's on the YZ side but not ours. My bike fouls plugs every ride now and my mechanic in PA has said that he has 7 other bikes with the same problem. Now, most are 2001 and 2002 YZF's but the CDI change has fixed 4 so far.

I searched the old posts and didn't find anything current on the topic. So are these bad boys a problem and if so what is the best brand to replace it with. Because the thought of buying another piece of junk from Yam. with no warranty since it is an electrical part enoys me.

Also, if anyone has the Yam. part # for the odometer hub spacer replacement I would apprec. it. I hacksawed the hub open to use the spacer inside the plastic, and it is rusty now and my dealership has now ordered the wrong spacer twice.



as an option, there is Vortex, distributed by

There is another, WULF I think. This IS FMF's discontinued AOF ignition.

Just to make you feel sick, FMF was dumping their AOF ignitions for $99.00. They ARE all gone!!

There is some test data and a chart in the archives that shows that the Yamaha Stock ignition has a higher curve and performes better than the Vortex.

Have you ruled out rich jetting or restricted air intake as a source of the fouling?

Bonzai :)

shot in the dark:

Have you checked your TPS (throttle position sensor)?

Originally posted by YAMAKAZE:

There is some test data and a chart in the archives that shows that the Yamaha Stock ignition has a higher curve and performes better than the Vortex.

Bonzai :)

This is the wr ignition with the grey wire mod vs. the 400$vortex.

Well as far as jetting goes nothing has changed for over 1 1/2 years without any problems. The only time I have had to change a start plug before this problem was just for fun when I got YZ timed.

No air restriction and I have replace the air filter also. The reason I'm sure it is the CDI is that if I put a new plug in, it runs like a raped ape. Then when it sits and I go to ride again "bang" fouled plug and tired leg from kicking.

My mechanic also has too many other bikes with the same problem and he has gone through every bike and nothing checked out bad. He and I discussed the CDI potential cause, and a few hard core racers he services just said to order it and put in on. Of course the bikes are fixed.

I'm just afraid of spending $200.00 for more junk.

Thanks for all the help anyone can give me.


I have also been struggling with plug fouling, I don't think it is my jetting but every other ride or so the plug fouls. I can check the plug and everything looks good, then next ride I go out and it fouls.

What about the blue wire mod? I think I saw somewhere to try this if you were having trouble with fouling plugs. I believe it effects the ignition in neutral.

I have not tried it yet but anything is better that changing plugs all the time.


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