400ex smoking, horribly

[EXracer83]

From the time you start it up through the entire time it runs hot or cold it smokes like a old western train lol. It is all blue smoke. I would say the rings were bad in it but this thing hasn't lost a like of power like other bikes I have owned and the rings were bad or the piston was toasted. I have been searching around and I am wondering if maybe its the o ring on the right crankcase where the clutch lever goes into the motor because I noticed it is leaking and my dad had said something about a air leak in the crankcase would make it smoke or something like that. Or could it be my valve seals are just gone completly? If yall can help that would be great, all tips and advice are welcomed, please help me. Like I said though, it doesn't seem like it has lost any power at all it still pulls hard and beats the other 400's I have always beaten but it turned into a mosquito sprayer! Thanks

[trx400EXtreme]

check ur oil. blue smoke normally has somthing to do with oil.

[trx400EXtreme]

actually it probably is ur valve seals if it hasnt lost power.

[Honda#4]

All I can say is Valve seals are toast. I'd stop now before you blow the motor up and have to spend double the money to get it fixed.

[EXracer83]

Thanks, I read it after I posted and it sounds like I been ridin the heck out of it like that lol. I rode it for maybe a hour all at one time since it started the smokin' but thanks imma tear into it prolly next week after I get my racecar back together and I'll let yall know what was up. Thanks for the help.

[04exking]

I noticed that in your signature that you have a blaster. I would put my money on that you put premix in your 400ex unless you are 100% positive that you couldn't have made a mistake I wouldn't tear into it.

[vett_09]

The pre mix gas is definitely something to check. Still, my friends 400 went the fastest it ever had the last 10 hours before the motor blew. I was riding it because at the time mine was tore apart because I was building it to 416. You wouldn't have thought by the way it was smoking it would have run at all, but I was hill climb drag racing with it. And just so I don't look like a moron, he told me to take it up north that weekend and ride the crap out of it because he was going to rebuild it anyway. I was riding my CRF450R until I laid it down and snapped the handle bars in half...

[EXracer83]

Originally posted by 04exking
I noticed that in your signature that you have a blaster. I would put my money on that you put premix in your 400ex unless you are 100% positive that you couldn't have made a mistake I wouldn't tear into it.

I know I haven't run premix in it because the Blaster ain't been run in 6 months because it needs another frame. Everytime I filled it up I believe I was at the gas pump when I did it. You can also smell the smoke and tell it ain't premix its burning motor oil badly

[04exking]

ALright then I guess it has to deal with your valves Because it is not your rings if it still has plenty of power like you stated.

[Honda#4]

If he had premixed gas in there I doubt that it would even start.Even if it would start it would probably make pukeing sounds I think. Be sure to tell us whats up with it.

[onesexyrider609]

Check your PCV valve I think it is. It's the left clear box on the left hand side of the seat, oil and residue from blowby or bad seals will go there. See if there is any accumulation. At least I'm pretty sure that is what it is, a less sophisticated Positive Crankcase Ventilation system found on cars. Hopefully I'm some help as to finding your problem:)

[EXracer83]

Yea it was the valve seals!! I just got done tearing everything down and the one I didn't destroy while taking them off had so much slack on the valve it was pitiful. Each valve is coated with carbon but the exhaust valve has a 1/4 of a inch built up on it (no exxageration) its a miracle my valves ain't burnt! but the cylinder is in great shape no ring ridge, egging, scratches, no piston play it looks like new just about. thanks for all the advice and I'll let yall know how it runs when I get the parts but that might be a while cause im broke right now and can't work till skool gets out but hopefully i can come up w/ enough money for the seals and timing chain before too long. oh yea the timing chain...it was so loose it could have jumped timing but amazingly it didn't so imma order the crf450 chain, what year model do I need to get it from? Thanks again!!

[dabrowat]

My 03 400ex smokes a lot of white smoke when riding. Is that normal or what can the problem be? Thanks

[hondajoe05]

Originally posted by trx400EXtreme
actually it probably is ur valve seals if it hasnt lost power.

don't know about it being valve seals does it smoke horribly all the time? i don't have any valve seals on mine at all and it doesn't even smoke all the time... and how much oil does it burn in a hour not all the time will you lose power if a ring goes bad it could of jus snapped in the middle and still be working jus letting a-lot of oil by... or a head gasket would cause it to smoke and no loss in power... and if its the valve seals the only way you'll tear it up more is not keepin the right amount of oil in it i haven't had the money to fix mine and i asked every shop around they said as long as you kept oil level right nothing would tear up... it could be a stuck valve too does it make any noise's? it should if it smokes

[hondajoe05]

sorry about posting shoulda read it all first