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Smoke coming out of valve cover vent

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Hi. Just wondering if it’s normal to have white smoke coming for my valve cover breather. It only happens at high rpm. There is no smoke coming out of the exhaust at all.

 

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Some may be normal, it is a breather and intended to vent fumes. 'White smoke' (water vapor) is very normal if a bike was dunked in a river or stored in a humid environment. As the bike gets hot, the moisture is evaporated and vented as 'white smoke'. I'll assume your coolant is fine.

I am not sure how you can see it while riding as no responsible owner would sit there and rev the bike in the drive way.

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The OP PM'd me instead of posting. It takes time to be 'forum savvy'. So I have copied and pasted his PM here:
 

Quote

 

Conner wiltshire

Started conversation: 7 minutes ago

It’s a dirt bike. And it was doing it after I washed it and I let it warm up and all that Jazz. And must be normal then. It doesn’t do it off idle it only happens when is reved up and held there. And the coolant is not the problem. Thanks for your help!.

 

Edit: The forum is not working properly for Connor. TT IT is working on it.

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Doesn't the valve cover breather vent into the airbox?  How are you seeing it?

Yes it dose but there’s a drain plug by the front sprocket and I took that off to let some of the oil out and forgot to put it back in. Then when I reved the engine very little white smoke came out.

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If you've crossed water or washed the bike without that plug,

there's a chance water got in the crankcase vent hoses.

 

The bottom hose requires to be plugged for the engine's intake vacuum to pull vapors out of the crankcase.

Edited by mlatour

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4 hours ago, Conner wiltshire said:


Yes it dose but there’s a drain plug by the front sprocket and I took that off to let some of the oil out and forgot to put it back in. Then when I revved the engine very little white smoke came out.

Just for future reference, that plug needs to stay in (you probably know this already).  I've seen plenty of bikes without it (mainly beater bikes) but the motor will vacuum up dust if its not plugged.

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Just for future reference, that plug needs to stay in (you probably know this already).  I've seen plenty of bikes without it (mainly beater bikes) but the motor will vacuum up dust if its not plugged.

Ok. But do you think it’s normal for a bit of white smoke to come out at high rpm?

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Once the engine has been running at it's operating temperature for a while and burnt out any condensation,

by then no, white smoke isn't normal.

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Might have another issue causing the white smoke and possibly too much blow by. By the way that white smoke, or the oily fumes or mist that will be expelled by a high hour or poorly sealed piston ring to the cylinder, ends up in the air box going through the carb and back into the engine. Here is an old thread that talks alittle bit about it.

https://thumpertalk.com/forums/topic/828147-crank-case-blow-by/

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Might have another issue causing the white smoke and possibly too much blow by. By the way that white smoke, or the oily fumes or mist that will be expelled by a high hour or poorly sealed piston ring to the cylinder, ends up in the air box going through the carb and back into the engine. Here is an old thread that talks alittle bit about it.
https://thumpertalk.com/forums/topic/828147-crank-case-blow-by/

Yeah I’m not worried about it. It’s not losing Oil or anything like that. And runs good and has lots of compression.

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