problem

[JPhonda]

alright when i first start up my 400ex and give it some gas when its cold its smokes black. and if i put my hand in back of the exhaust and then rev the motor i am left with black hands. It only does this when its cold. I think that after is sits for a while some oil drips on the piston and thats whats causing this to happen. What do you guys think??


Another thing is i only noticed this after i put back my stock exhaust on. and that stock exhaust has been sitting around for years doing nothing.

Maybe its just time for a top end rebuild and ill install a 416 high comp piston.

[250x_kyle]

my 400ex did that. i put a new pipe on rejeted and it didnt do it anymore. it just seemed like some carbon build up.

[JPhonda]

could this problem be caused by the carburator and jetting. when i put the stock pipe back on i replaced everything back to stock

[miller821]

Sounds like your jetted to rich. If you went from an after market pipe and jetted it, then went back to the stock pipe you will have to rejet it. Also its doubtful that its oil cause it should be burning it (And it'd be blue if that was the case.)

When you put your hand back their is it actual oil coming out, or just carbon?

[Sparky_20]

your running too rich with the stock pipe. Go down on the main jet and possibly the pilot and youll be good to go.

[CarGuy7a]

me and my friend noticed that his 400 did the same thing. when he revvs it up it blows a little bit of black smoke out. nothing huge but you can see a little.

also what octane gas are you running. my friend just runs regular 87 i think it is but i run 92 in mine. i'm not for sure but that may be something to experiment with because the recommended octane says 92 or higher. maybe if you run 87 it may be causing a little more carbon build up or something and blowing it out.

[TYayo420]

for as little as these things eat gas, and as little as they take to fill up, it's stupid and not smart for any reason to run anything lower then 93 in them, i always run premium gas in my toys...not going to make ya go broke spending 25 cents more a gallon for good gas so thats abt 75 cents more to fill er up as if u were to use bumb 87 fuel...

it's also common sense..ppl spend alot on a wheeler, and after market parts, but wanna penny pinch to save 75 cents a fill up for cheap poopy gas.

[CarGuy7a]

Originally posted by TYayo420
for as little as these things eat gas, and as little as they take to fill up, it's stupid and not smart for any reason to run anything lower then 93 in them, i always run premium gas in my toys...not going to make ya go broke spending 25 cents more a gallon for good gas so thats abt 75 cents more to fill er up as if u were to use bumb 87 fuel...

it's also common sense..ppl spend alot on a wheeler, and after market parts, but wanna penny pinch to save 75 cents a fill up for cheap poopy gas.

i'm with you on that. of course i like to sometimes throw some VP 105 in her from time to time. besides the stuff smells great.