I am seeing white or very light gray deposits on my exhaust tip. I am running leaded race gas in a 4-stroke. The motor is running very rich. Is this just the color of leaded race gas deposits when you are running rich or is this an indication of something wrong with the motor?

 

Scooby, mine is just like that too and I run unleaded 98 oct.
I think it happens when the engine is running perfectly.
JNBOMB650

 

I saw this on my exhaust tip too the last time I was out. I had been adjusting the jetting from rich to lean and then back towards rich when I noticed the light gray color on the discs. It really freaked me out to see it because it looks like vaporized aluminum. I feared that I had burned the valve seats from running too lean and had aluminized my exhaust pipe the expensive way. Hopefully its nothing- but it was running like crap at the time.