Smoking Problem?

[400ex drifter]

My 400ex was smoking out of the exhaust pipe when I hit the throttle, so this week I decided to try to fix it.

I put in new piston rings (piston was in great condition), valve seals, and cometic top end gasket kit.

I just finished putting it back together and started the hard break-in method when I realized that it is still sending bluish-white smoke out of the exhaust whenever I hit the throttle.

Could this be a jetting problem of some sort? Too rich? Too lean? I'm running a 170 main jet, 42 pilot jet, and the needle on the stock position. Any help will be appreciated.

[hocman123]

it could be jetting but i dout it the jetting sounds really good for ur set up. the only thing i would say is maybe u didn't hone the sleeve before putting in the new rings which u should do to insure a good new seal on the rings. also did u mic the sleeve to see if it is still with in the limits u might just need a bigger bore

[ridehonda400ex]

Yeah Sounds like your bore might be out of round. Definitely get that fixed cause it sounds like your burning oil still

[400ex drifter]

I honed the cylinder while I was down there so it can't be that. Also, I don't think that the cylinder would be out of round because the piston made 190psi on the compression check.

The smoke smells more like unburned fuel than oil, so I just changed my main jet down to a 165. It didn't smoke as much, so I guess it is just running really rich. I guess I'll just keep going down on the main jet and adjust the needle position. What do you guys think?

[tri5ron]

Originally posted by 400ex drifter
I honed the cylinder while I was down there so it can't be that.
Honing and boring are 2 different things.
if a cylinder is "Egged", and you only run a hone through it,... chances are, it will still be "egged".

Originally posted by 400ex drifter
The smoke smells more like unburned fuel than oil, so I just changed my main jet down to a 165. It didn't smoke as much, so I guess it is just running really rich. I guess I'll just keep going down on the main jet and adjust the needle position. What do you guys think?

What do I think you ask,
here it is...

You originally said the smoke was a blue-white color. That indicates it's burning oil.
This MAY be due to residual oil in your packing from PRIOR to the "Hone" job,.... but I doubt it.

going down to a 165 main, on a 11:1 416 with a stage 2 cam, is getting dangerously low(lean) if you ask me. Going down further than that is asking for trouble.

I have a STOCK piston & stock cam, with a full system exhaust, Uni and Outerwears lid, +6 key, and a Dyno Tuned 450r carb.
I am running a 165 main (kiehen)... and that is for roughly 2000' to 3000' elevations.
(Ok, so I've also recently stepped up to a stage 1 cam, but the jetting is still the same).

Again, I say if you are going down to a 165, on a 11:1 with a stage 2,... you are running too lean, and are asking for trouble.

You need to positively identify whether you are burning oil or fuel.
Oil is indicated by blue/white smoke.
Fuel is indicated by black smoke.

You did not indicate whether you had properly measured the cylinder before your hone job, as well, you do not indicate if you had properly measured after your hone job.
All you said is that you decided to "try to fix it", and put in new rings / valve seals, with a hone job.

I'm guessing that the cylinder was "Egged / Barrel shaped" before you honed it, and now it STILL is.

My suggestion would be to pull it back apart and have it PROPERLY measured, as well as measuring to piston too.

This will eliminate the question of whether your cylinder is "Good" or not.

Sorry, but 190 psi will not tell you that.

If you keep dropping your main jet size, on your engine combination,... you are going to burn it up.

[the Z Man]

Your not running gn4, honda oil only, it will go away, trust me, I went through the same thing..
Your not running Honda oil are you?

[01boneless]

i had this same prob pull you head pipe and see if both ports have oil in them if only one its an issue there with that valve assembly if both then its probley something down towards the piston