I'm a bit confused by my service manual. It says that the XT125 ignition advance is 9 Deg at 1300 rpm, 29 deg at 6000 rpm and the XT200 is 9 Deg at 1200, 35 Deg at 6000 rpm.

All ignition componants are the same between the 2 bikes. How can they have different advance curves?

ok, so I checked mine to see if it was advancing. It doesn't seem to be according to my cheapo innova 3555 timing light.

The reason why I started to look at is because my XT125 has very poor performance; top speed is about 40 mph and it seems to bog the whole way there.

What causes the advance in this bike? Is it solely the CDI or is it a combination of componants?

There are two pick-ups on the stator,probably one is a low speed and the other a high speed.I would check the coils on the stator for proper resistance.
The xt125 was no known for its performance but it should pull smoothly up tp about 60 mph..

nsman, on 08 August 2012 - 06:48 PM, said:

Thanks for the response.

There's only one pick-up. From the parts diagram there appeares to be 2 but it is not correct.

The resistance is within the specified range. I checked all coils while I was at it and all were within the correct range. I guess I'll bite the bullet and buy a new cdi.

How could the 2 bikes have different timing advance? I wonder if they originally had different cdi part #'s but has enventory of one got depleted, they just substituted it with the other.

Edited by gearhead86, 09 August 2012 - 03:46 PM.

I think the CDI boxes were originally the same,only thing I can think of is that because the piston strokes are different the timing numbers are different....
if everything checks out with respect to the stator and coils,Then it is reasonable to replace the CDI.
  Good luck.

Try heating up the cdi box and see how it runs if it runs better when heated then the cdi is definately bad just a test i donno if it will work in your case but it did for me.  I had a 82 xt200 and when i bought it it had no spark after looking all over the internet on how to test the cdi i finally found someone that said to heat up the cdi.  So i heated it up with a little propane torch an it started an ran good until the cdi cooled off after sitting then it had no spark.

well, got a new cdi. its much better now. Can hit 50 to 55 now with my 210# butt. Probably could have gone a bit faster but ran out of street.

I'm still baffled by how the xt200and xt125 can have different timing curves.

P.S.
It still seems gutless. i guess thats par for the course. It is a 125cc 2-valve engine after all. I had this bike when I was 14 years old (30 years ago and 50# lighter) and it seemed to pull abit harder back then. Should be good for my wife for a while though.

Edited by gearhead86, 03 September 2012 - 10:34 AM.