little smoke at start up

ever since i did the jd jet kit, fuel screw, uncorked, grey wire etc (which was only 2 rides ago), my bike has smoked just a bit at start up. when it is fired for the first time after sitting say a couple days, it will smoke for 30 seconds to one minute until it is warm. and it ONLY smokes when you blip the throttle. it does not smoke when it is sitting at idle warming up with or without the choke on. only when you blip the throttle will you get a little puff puff out the exhaust pipe. sometimes it looks black. sometimes a little blueish white. once it is warm...nothing. everything goes away. it did not do this at all before these modifications. but has done it ever since the first start up after modifications. suggestions? again it does not just sit and smoke for a minute, but when you blip the throttle you will get puffs out the back until the bike is warm.

-hop

is it a 2t or a 4t

I have the same prob on my 2011 wr450 after jetting. Black smoke is unburned fuel. I cholked it up to excess fuel in the cylider at fire up from the bigger jets, choke, and the accelerator pump (did the o ring mod to) goes away when the pipe and engine get hot enough to burn it completely. I am sure the head pipes could burn off toxic waste at the temps they run.

i did the o-ring mod too

Valve stem seals. The oil from the top end will seep around the valve stems when it sits. I had this happen on my WR a few years ago, replaced the seals and it no longer smoked on startup.

is that costly?

Valve stem seals. The oil from the top end will seep around the valve stems when it sits. I had this happen on my WR a few years ago, replaced the seals and it no longer smoked on startup.

:):D

is that costly?

Nope. the next time you do your top end, have the machine shop take care of it for you. It will cost very little, like $250, to get the valve seals replaced, new seats cut and the entire head cleaned up. (You have done a top end, haven't you?)

In the mean time, keep an eye on that spark plug. If it gets all gunked up with oil, change it.

Edited by mauricedorris
(You have done a top end, haven't you?)
no. the bike only has just over 730 original miles on it. :)

Mines got 6500 on it after today and usually when I turn it on from cold it smokes a bit of oil for a few seconds then stops... Not sure why either but it hasn't bothered me

Valve stem seals. The oil from the top end will seep around the valve stems when it sits. I had this happen on my WR a few years ago, replaced the seals and it no longer smoked on startup.

sounds like this

My WR426 does the exact same thing. Once its up to temp (about the time I take the choke off) it completely goes away. Its hit or miss too--sometimes it does it and sometimes it doesn't. I totally agree it has to be the valve stem seals :)

may want to reinstalling the old jets to eliminate the over fueling condition befor you tear into the motor to do the valve guides since you noticed the condition right after richening the jetting. that won't cost a dime and only takes a half hour.

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