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Hi, New to the site here (awsome site). I purchased a 2008 TRX400ex (new) in Mid. October 2010 for my daughter from Performance Honda in Wesley Chapel, Florida. After less than 9 hrs of use it is blowing white smoke (Oil Smell) during engine braking after a long ride. Took it back for them to look at and was told they changed the plug and it needs to be broken in the rest of the way. I've been a mechanic my whole life, and I know that while engine breaking/closed throttle manifold vac. is high and the oil is coming from the valve seals or passed the rings. I'm posting hoping to find other people that might have had this problem. Any help would be great, Thanks.
 

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mud99, It makes a few dense puffs while on deceleration, nothing while on throttle. Im going to do the 10hr. service this weekend and ride it some more. Will post what happens, any ideas? Thanks.
 

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Could be its not fully seated yet. Give it some time and if it keeps it up Id have it checked under the warranty.
 

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its your rings bro. i have a 2008 400ex and it smokes too. i kno two other 400ex's that smoke real bad and its just becuz the rings are goin out. it will ride forever before it ever really does any damage bt the only thing i can think that would make them go out so fast is becuz i keep mine on two wheels most of the the time and therefore oil aint gettn to the top of the motor
 

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have same problem

Hi, New to the site here (awsome site). I purchased a 2008 TRX400ex (new) in Mid. October 2010 for my daughter from Performance Honda in Wesley Chapel, Florida. After less than 9 hrs of use it is blowing white smoke (Oil Smell) during engine braking after a long ride. Took it back for them to look at and was told they changed the plug and it needs to be broken in the rest of the way. I've been a mechanic my whole life, and I know that while engine breaking/closed throttle manifold vac. is high and the oil is coming from the valve seals or passed the rings. I'm posting hoping to find other people that might have had this problem. Any help would be great, Thanks.
hey i have the same problem under the warranty my bike been in the shop 4 times already and have a lawsuit against american honda for this problem if i were u still under warranty seek a lemon law lawyer if u want my lawyer i can give it to you she works all over the world.
 

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Motors are pretty simple machines though the causes for smoking are many.

Smoking on startup usually indicates either or both intake or exhaust valve seals.
If it smokes a little on start up and smokes worse when it gets hot, but it never fouls a spark plug and the plug has normal coloration, it's usually an exhaust valve seal.
If it smokes a little on start up and gets worse as it gets hot and it fouls plugs a lot, it is either intake valve seals or rings or both.
It might be the motor was not broken in properly and the rings are damaged. The most common mistakes during break-in is over heating and over revving. You can over heat the motor by letting it idle for more than 5 minutes. Over revving is self explanatory. During break-in it is OK to give it full throttle, just don't hold it at a high rpm, get off the throttle or shift. Riding down a road at high speed does both over heat and over rev. Riding too slow can over heat it too. Best break-in method is "pasture riding". Not too fast, not too slow, shifting up and down, make the engine pull and let the machine push the motor. Heat and cool cycles are important too. Ride for 15 minutes and let it cool for 30 minutes, ride for an hour, let cool for 2 hours.

In older engines I have seen oil rings worn out from dirty oil while the compression rings were fine because the air filter was serviced regurlarly.

Whatever the problem is, it can be corrected and remember - most problems are simple - humans just try to imagine the worst.
What kind of oil do you use? Synthetics are slicker than petroleum oils and get past the rings easier. Engines most generally should be broken in with petroleum oil. They will break in on synthetic, but it will take longer.
 

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I have a 2007 TRX400EX and there is white smoke coming out of the tailpipe havent turned the quad on in over a year. Smokes the entire time while riding. Any suggestions would be helpful. Great forum btw.
 
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