06' Ninja 250 White/Gray Smoke

[ChaseSpicer]

Hey all,

I just finished doing a carb swap and after I did some tuning to the idle and mixture screws I was running fine. This all ended after finishing up an hourish ride with my buddy. I was near my house when my bike started putting out white/gray smoke from the exhaust and rapidly fluctuating rpm without me moving the throttle. I got it home as quick as I could and took a look at everything. The only things I noticed was the tube connected to the bottom of my airbox (and maybe to the crank/cam housing - not sure) was loose and I also realized the I never attached one of the two metal bands that holds the airbox to the carburetor. The next day I fixed both issues, and also emptied out some oil (I noticed that I had over a decent amount over the max fill line when held upright), but now when I start the bike without choke my bike idles at 4-5000 rpm. And will occasionally stall after a while if I don't apply choke or mess with the idle screw.

Any thoughts appreciated

Also I forgot to mention that I have not noticed any smoke since the other day.

[SibSerge]

As I understand you had air leaks through that hole on the airbox where the crankcase venting tube was supposed to be connected to and possibly a leak through the boots that were not tight. So you tuned your carbs with the air leaks in place. Now after you fixed the leak you need to re-tune it at least and go from there.

[DannoXYZ]

Originally Posted by ChaseSpicer

but now when I start the bike without choke my bike idles at 4-5000 rpm. And will occasionally stall after a while if I don't apply choke or mess with the idle screw.

Sounds like idle and/or pilot circuit is clogged. Needs thorough cleaning.

[jkv45]

Originally Posted by ChaseSpicer

Hey all,

I just finished doing a carb swap and after I did some tuning to the idle and mixture screws I was running fine. This all ended after finishing up an hourish ride with my buddy. I was near my house when my bike started putting out white/gray smoke from the exhaust and rapidly fluctuating rpm without me moving the throttle. I got it home as quick as I could and took a look at everything. The only things I noticed was the tube connected to the bottom of my airbox (and maybe to the crank/cam housing - not sure) was loose and I also realized the I never attached one of the two metal bands that holds the airbox to the carburetor. The next day I fixed both issues, and also emptied out some oil (I noticed that I had over a decent amount over the max fill line when held upright), but now when I start the bike without choke my bike idles at 4-5000 rpm. And will occasionally stall after a while if I don't apply choke or mess with the idle screw.

Any thoughts appreciated

Also I forgot to mention that I have not noticed any smoke since the other day.

I would say either you have a vacuum leak (between the carb and the engine) or the choke mechanism is sticking either internally or externally.

A vacuum leak could be a clamp is not secure or even cracks in the rubber manifold. Spraying around that area with carb cleaner when it's idling and listening for a change in RPMs will tell you if you have a leak.

Your initial oil/smoke issue sounds like it was related to the over-fill, so you should be good after draining the excess.

[ChaseSpicer]

Thanks for the help. Ill try the carb cleaner, but when you say spray near the vacuum tubing is that the vacuum tubes coming out of the carb?

[jkv45]

Originally Posted by ChaseSpicer

Thanks for the help. Ill try the carb cleaner, but when you say spray near the vacuum tubing is that the vacuum tubes coming out of the carb?

To check for a vacuum leak, spray around the forward clamps on the carb/manifold connection, the rubber manifolds, and around the manifold connection to the head.

Any change in RPMs tells you there is a leak.

You can use other things as well, I just usually use Carb Cleaner.