Well I got my bike all torn down and I was very surprised to see what my piston looked like. So, why does it look like crap? My bike has no mods what so ever, and I used premium gas.

2500 miles on bike

 

Looks like normal carbon build-up. Any scoring on the skirt? What mileage?

 

No scoring on the skirt, and I forgot to say almost 2500 miles.

 

The deposits could be the additive that raises your research Octane level. Not all "Premium" fuels are top-quality. Octane is NOT a measure of quality, it's a measure of resistance to detonation prior to an external spark firing. Unless you have done something to make your compression value higher than stock, you're engine does not require high Octane.

 

As odd as B58's comments sound about premium, it could be the reason for some of those deposits. Regardless, it's a common thing to have some noticeable buildup on the piston crown. What does your combustion chamber in the head portion look like?

 

i've only used premium 91 octane...all fast high rpm riding...7,000+ miles...engine piston was checked at after 5,000 miles...just a towel to wipe and it was smooth and clean....being in california, it rarely sits...ride it a lot...roughly 1,000 miles per month....

 

That is exactly what I was thinnking when I read that he uses premium.

I have a V6 Mustang that I change the "Tune" with a programable tuner (SCT tuner) I have 3 three settings. 89 Octane Fuel Economy, 89 Octane Power, and 92 Octane Power. The 92 Octane Power setting advances the timing and if I dont have 92 in the tank it will Ping. With 92 in the tanik it will rip. So, like it was said unless you have something changed like timing or compression use the lowest octane you can get with out the bike Pinging.

I also have a Camaro but it is all stock, and it blows the doors of my Mustang and it uses 87 octane.

 

I used premium because in the back of my owners manual there is a sticker that says premium gasoline only. When I bought my bike the dealer pointed it out to me, and they said they put the sticker there based on a service bulletin from kawasaki. Maybe it should have went in another manual and got put in mine by mistake?

What should I be using with the 351 kit.

 

Combustion chamber looks as black as the piston. Perfect match which may not be a good thing.

 

Looks like the typical carbon build up from an engine choked out from the factory.