Possibly new rings after rebuild

[mad4106]

Just got my 400 rebuilt to a 440 I was racing at the dunes all day temp was in the seventies not too hot and then the last race I notice white smoke coming out the pipe. I did miss 3rd gear a couple of times so the motor was revved out in 2nd. Any suggestions?

[400exwhipper]

When mine gets real hot it will puff a little at rev limit, how much smoke are you talkin?

[dxcody]

Did it feel hot?

it is hard to tell sometimes which smoke is which.

When oil is burning bad, your smoke is bluish but when it is just barely coming out or if you just flooded it a little it could have been carbon build up. It just depends.

First thing I would do is, pull the plug, post a pic or if you are good at reading them, see if it is oil soaked, carbon caked, lean, etc.


Dunes are typically ideal riding spots mechanical wise (except on clutches) because the sand keeps everything clean and it is usually pretty open so you are getting a lot of air flow.

Pull the plug see what it looks like, if it looks like a normal plug, then fire it up and see if it is smoking.

Check back afterwords.

[mad4106]

thats exactly what it is doing is smoking a Lil at rev limit it was a Lil hot.

[JOHNDOE83]

You might need more then the 185 main, if I run any less then a 210 main I get to lean and pop/hesitate during heavy acceleration and build up way to much heat.

You need to buy jets in incriments of 5 from 185 up to 220, start at 220 and go for a ride. If it doesnt fully rev out drop down sizes in incriments of 5 till it will fully rev out.

Thats the only and best way to jet for main jet.

[mad4106]

we checked the plug after a few passes it was a light tan color

[dxcody]

The whole thing? Or black threads with the tip a light tan color?

If the whole thing is light tan, you are way lean.

[mad4106]

It looks like number 19 which is good it's the plug chart color on here in the forum

[JOHNDOE83]

Plug color doesnt mean anything in these air cooled motors with the gas additives these days.

You have to "especially with a 440" jet the main jet with the jetsrus method using the largest size main jet and working your way down in incriments of 5 until it fully revs out.

Without cutting threads of your spark plug, you will NEVER get a main jet reading.

Check out the jetting section at www.jetsrus.com and look for main jet, then read.

I bet you need atleast a 210 main.