White smoke from engine when warmed up

Hi, I have just got my 1976 KZ 400 running after sitting for 10 years. The bike is a bit cold blooded but runs and idles great when warmed up. After about 15 minutes there is a fair amount of white smoke that appears coming directly from the motor and comes out under the seat/tank area . The crank case vent also has white smoke coming from it (not a ton) the bike has k&n pods on it. It has a fresh oil change and fresh gas. Other than the smoke it runs and rides good. Can anyone help diagnose? Thanks in advance!

How long since you got it running? Looks like the bike is burning off residual oil or maybe it's steam when it gets hot. Does it continue this way after a nice long ride?

I’ve only taken it on a couple test runs.. the longest 2 miles as it’s not registered yet, that’s when I noticed it... I also ran it in the garage for a half hour hoping that that may be the case. The motor seems relatively clean, no leaks that I can see although the seal at the top of the cylinder head seems to be moist/wet.

White smoke is almost always water, either from condensed vapor or coolant. We can obviously rule out coolant on these bikes.

Lots of short trips or just sitting for a long time will cause moisture to condensate inside the engine and exhaust. If you give it a decent ride (1/2 hour at the least) it should fully heat up the engine and clear it up.

Thanks for the reply, I will try to get a decent half hour ride in... in case my description was unclear or confining, the white smoke I ant coming from the exhaust, but from the motor itself. I and a novice at motorcycle mechanics and appreciate all the help!! Thank you!!

Dvbish wrote: in case my description was unclear or confining, the white smoke I ant coming from the exhaust, but from the motor itself.

Ah OK. Same deal, it's likely just moisture and other liquids on the surface flashing off. If you've degreased the engine, or even just handled parts that get hot like the head or headers, they will smoke up a little when getting hot. The oils in your hands will stick and stay there until hot. If it's been in the rain there are also a few little nooks that can trap small amounts of water.

Do look out for oil leaks though, the valve cover gasket and the rubber caps at the end are pretty common candidates for leaking. A leak at the front can drip down onto the headers and smoke up.