smoken it up

[blasterheavyB]

i have an '04 400ex and i recently ran a race with it and i knew it was smoking during the race but then after i washed it and ran it it is now smoking realy bad any body have an idea what the problem might be the smoke is black not blue so its burning oil

[EXriderO2]

if it smokes when u start it up ur valve seals are bad, if its smoking and burning oil its time for a new piston/rings. i had the same problem with mine. dont ride it until its fixed cause the friction can cause the cylinder to score and thats even more money you have the spend

[blasterheavyB]

it smokes bad while riding and how much money are we talking just for parts here

[EXriderO2]

mine is being fixed as we speak for the same reason, i ordered the 10:1 wiseco piston kit standard bore fpr 88.95 off of rockymountainatv.com and i also ordered a tusk gasket kit off that website for 20 bucks. the gasket kits come with the valve seals. but i would reccamend having you heads redone at a napa store while you have it apart, that costed me 60. so right around 200 for the parts. Check your vavles and components for wear also, you dont wanna put it back together with worm parts. good luck man

[underpowered]

Originally posted by blasterheavyB
i have an '04 400ex and i recently ran a race with it and i knew it was smoking during the race but then after i washed it and ran it it is now smoking realy bad any body have an idea what the problem might be the smoke is black not blue so its burning oil

black smoke is fuel, not oil. black smoke is a sign of being to rich, but a light blue smoke is burning oil.

if it is in fact blue smoke, could be valve seals or piston and rings. either way the top end has to come apart.

[EXriderO2]

one way to find out for sure is to check you compression, good compression ranges from 100-128 psi. and also check your oil level. if its low then its gotta be going somewhere. (burning)

[blasterheavyB]

so with it being black smoke what would the problem be and how do you go about checking the compression

[EXriderO2]

mine was black smoke and my compression was at 90 psi, and my oil was burning. take ur spark plug out n get a compression tested and screw it in ur spark plug hole n hold the throttle wide open and turn the engine over until the gage stops moving. if its below 100 psi then change ur piston and rings and if it smokes when it starts its ur valve seals, smokes when ur riding means your rings are bad and burning oil. you can buy a tester at an auto parts store just make sure its a small engine tester

[underpowered]

black smoke is a sign of running rich. you main jet is to big, ir may have come loose and just fallen out. you can check the compression anyway if you want, but in general:
Black smoke-too much fuel. the smoke is the unburnt fuel.
blue smoke-burning oil
white smoke-burning water.

with a stock cam, normal compression is about 120. anything below 100 and it probably won't even start, atleast with the starter anyway. with an aftermarket cam with no decomp. mechanism a good number is 180 or so depending you your comp ratio.

a comp test is quick and easy. if it is your valve seal, it will smoke on start up and decel. and sometimes during normal riding. will will also be buring some oil. rings it will smoke all the time,and you will be losing oil as well.

[EXriderO2]

/\ What he said is correct. before you buy nething just check your compression to be safe.

[blasterheavyB]

sounds good i will run by the auto parts store and try to get one tommarow and let you guys now what i read it at