White smoke after warm up.

I'll probably do the top end this winter anyway, but I was wondering if anyone could diagnose the problem. I have an '81KZ750E with about 28,000 mi. The bike, just recently, started blowing some stinky white smoke from the exhaust, but only after a complete warm up. The onset of the problem came on quite rapidly. I have'nt performed any diagnostics such as compression, however two of the cylinders look like they are running rich, as determined by looking at the plugs. Thanks

I would first suspect Valve Stem Guides.

Spock

Oil smoke is rather stinky, but gas smoke (due to rich mixture) will make your eyes burn.
So, which is it?

Burning oil type. Pretty smelly stuff.

If the 2 cylinders that are fouling plugs are 2&3 I would suspect the O ring around the camchain galley/head gasket.I have an 81' J motor that has developed an oil leak out of the front of the motor and thats what I suspect on it.

just my .02:)