When I left for work one morning my bike started running rough, so a mile down the road I turned around. In the 2 mile trip my pipes turned a blue/purple color. From what I've looked up this means it's running lean. It's both pipes evenly. I replaced the rubber intake gaskets, and the little vaccum seal. I'm wondering if my carb brought up some debris, any second opinion would help. Thanks!

 

Retarded timing will do that too....check it hasn't slipped.

 

Check the timing first as it's the easiest. Just remove the cover and see if there is any indication of the plate moving. If not, then it's time to check the fuel system out. Look at the vents, fuel lines, petcock vacuum, and then the carb.
John

 

Maybe a vacuum leak making it lean, recheck the carb mount.

 

It has a mechanical advance, and one of the springs is broke. I've gotta figure that's what is wrong. The accelerator pump needs replaced, but the carb was a lot cleaner than I expected. Thanks for your help. Don't ask why it has a mechanical advance

 

"Mechanical advance" on a '99 EVO? You don't have an electronic ignition?

 

Yes, it is currently running on points and condenser. The ignition module quit on me completely, and left me stranded. I'm pretty happy with the the older ignition, until my recent problem, but at least it still got home under it's own power. I'm running the factory coil, and I still have the ignition module on it because that's what the coil bolts to. I will probably go back to the factory design, I just needed something to get me through the season.

 

Understood - as you've just become aware, an overly retarded ignition curve can indeed cause overheating. If you look on eBay - or ask here, you can probably find a stock ignition setup for the asking from someone who's gone aftermarket.

 

I changed my old 84 Sportster to points when the ign. module went bad on it, and I think it ran better than before. I did change to the points type coil as they do operate at a different secondary voltage. I carried a spare points and condenser with me, but I never needed it in 20,000 miles. At least if it did quit I could fix it, and it was $35.00 instead of $145.00.

 

If it is overheating Not to be funny but have you checked the oil tank for bubbles to make sure the pump is working?

just a thought