RMX250 Excessive Smoke After Rebuild

[KingKouf1]

Hey guys recently I have done the top end of my RMX250 1999 Model.

It did not smoke much before doing it and was running ok, was just a little low on power and compression and the power valve was sticking.

 

Did the top end and first kick it fired up but I had forgotten to turn the fuel on so it revved pretty high for the first second before I killed it, turned on the fuel and re started it.

The bike smoked like crazy but I thought that was just a bit of oil that I had used on the rings getting burnt off. Anyway, the smoking isn't stopping, I have given it a few heat cycles and a gentle ride and she is still smoking like crazy and the smoke is darker than usual. What could I have done when doing the top end that could cause this.

 

I have attached a video of the bike once it's been completely warmed up. (video doesn't do justice to the amount of smoke coming out)

<iframe width="560" height="315" src="https://www.youtube.com/embed/PQWzJTOnXgc" frameborder="0" allowfullscreen></iframe>

[JHN6737]

Doesn't look too healthy does it??

You mentioned the power valve was sticking...have you sorted it? If it's really gunked up bad then it could need cleaning. Thick dark smoke can also indicate bad crank seals but I wouldn't think it's this if the bike wasn't smoking before you rebuilt the top.

Edited May 12, 2017 by AE448

[zig06]

In my opinion your bike just isn't warmed up yet.  Sitting there (or anywhere) and rev'ing it up won't do the job, you need to put a load on it.

I suggest that you top off the tank and go for a ride.

[KingKouf1]

On 5/12/2017 at 11:05 PM, AE448 said:

Doesn't look too healthy does it??

You mentioned the power valve was sticking...have you sorted it? If it's really gunked up bad then it could need cleaning. Thick dark smoke can also indicate bad crank seals but I wouldn't think it's this if the bike wasn't smoking before you rebuilt the top.

 

Yeah completly pulled apart and cleaned the power valve and inspected it, it was working perfect.

 

[KingKouf1]

On 5/13/2017 at 2:28 AM, zig06 said:

In my opinion your bike just isn't warmed up yet.  Sitting there (or anywhere) and rev'ing it up won't do the job, you need to put a load on it.

I suggest that you top off the tank and go for a ride.

 

That was after riding around my backyard for 10mins.

 

The smoke actually cleared up eventually and I went for a ride. All of a sudden she just bogged out, smoked loads and died unable to be restarted. Not looking forward to pulling it all apart again. 

[zig06]

Check your crank bearing seals (clutch side).  If it's smoking really bad and that smokes "hangs" in the air then that's burnt gear oil and that's the only way it can get into the cylinder.

Edited May 14, 2017 by zig06

[TheArmageddon Lemon]

Ok so ive put 10 hours my my 2000 rmx250 after replacing every part that can wear in the engine. These bikes do smoke quite a lot, mine has since i rebuilt it, its just something to get used to. Also theyre a little funny with warm up, they wont properly rev out or have that good two stroke rev until youve gone through the gears once or twice after warm up. Mine falls flat every gear until ive run through all of them once, then it hauls like a freight train. I have not had a single problem with mine in the 3 years ive own it.