carbon build up on piston

[drummer-on-a-EX]

I just took my motor apart to install a new high compression piston and hot cam, the old piston and bottom of my head has a significant carbon build up, it has about 250 hrs on it, I run 91 octane gas and a dpr8z spark plug which doesn't look bad(nice brown color).
My question is, is this build up common, should I be running a dpr9z plug?
Any advice or suggestions welcomed.

[ESR250R]

i had a carbon build up on my quad as well and it is caused by running too rich.

[DEAL]

You have to expect a little carbon build up.

[skemp]

Actually, a lot of carbon build-up on the piston (piston wash) is caused by running too lean. When it is richer, the gas "washes" away the carbon deposits and leaves the piston clean. Carbon will always be present though, I wouldn't worry about it, just get your jetting spot on with the new piston and you should be good to go.

[airheadedduner]

It is also caused by running hot(or lean), or by running to low of octane fuel.

[z400ex]

lol.....

[z400ex]

actually skemp...its not from running to lean. See, if the bike is running rich ther is no such thing as gas washing it off....lol ther isnt any gas left it all burn. Carbon is caused by running to rich..:devil

i don't think any of you know what it's caused by.

[ESR250R]

u tell em thomas

[airheadedduner]

It was what the local mechanic told me. He said it is caused by preignition. I just took his word for it.

Why do you SMA guys always gotta start flames?? He asked for SUGGESTIONS. At least others are trying to be helpful.

[ESR250R]

i wasnt aware that i was flaming anyone....i believe the carbon build is caused by a rich condition, but thats on a 2 stroke. when a 2 stroke is rich it leaves behind excess oil that builds up on top the piston. but i dunno on a 4 stroke i dont think that running it too rich would cause that on a 4 stroke. i would tend to lean more towards the predetenation theroy. first i would check what kind of compression u have, then i would determine wheather or not to run premium, race gas or a mix. i was just told not to run a mix though because the race gas seperates from the premium. so i think that u need to run a better gas.

just my 2 pennies

I wanna know what happened to all the members that actually know something instead of all of these morons without a idea guessing and telling people what they think there mom's sister dad told them. I really think if you have no clue you should keep out.

[Bean]

yea, sma 416, u are the moron that needs to quite down, no one wants to hear u flame other people, cause u dont know what u are talkin about, and im tired of hearin it

yeah..i am the moron.leats i'm not some 15 year old punk makin up stuff so i sound smart. atleast when i do try to elp i use my knowledge and not some complete guess outta no where. and asfar as i care. i don't care about what you think.

[Bean]

u may not be a 15 year old punk, but u act like a 12 year old looser, get over ur big head crap and jus help people, dont drop on everyone that is wrong, or that u think is wrong...

oh..ok.next time i see someone giving out complete crap for help i won't butt in and try to help..OK