06 400ex smoking

[mbjtlr]

My buddy has a 06 400ex. It started smoking when he accelerates hard and when he lets off the gas at higher rpms. It smells like it is running rich when you are riding behind him. The smoke is a bluish, grey color, sometimes more white. He has kept up with his maintenance. It doesnt use any oil and it doesnt smell like it is burning oil. There has been no loss of power and it does not run any differently. It is all stock except for a Uni filter and he has removed the baffle from the exhaust. The local Honda dealer said it was his valves. I just dont see how that is possible considering how new it is and he takes care of it. Anyone have any ideals?

[trx400EXtreme]

Originally posted by mbjtlr
I just dont see how that is possible considering how new it is and he takes care of it. Anyone have any ideals? just cuz he takes care if it doesnt mean somthing cant go wrong with the valves.=/

[Shaun Martens]

My 05 is doing the same thing.

[hornetgod13]

I have the same issue. It's most likely the valve seals. C&D racing sells viton valve seals for $5.00 for a set of 4 but, they have a minimum order of $15.00. Stock seals are much higher.

[QuadManiac]

If he is running a freer flow filter and exhaust, he may need to rejet. He is likely running lean, which may be the cause of the blue smoke - heat damage to the valve seals due to an overlean condition.