White smoke

Hey guys. So the bike starts and idles fine. But when revved to 4k rpms or higher quickly it gives a puff of white smoke out of the exhuast. Any ideas what could be wrong and how bad is this?
Thanks!

Are you revving the engine up like that with the bike sitting still?

Yes. The bike was in neutral warming up when i first noticed. I let it sit for about 15 minutes with a fan to see if it was something small that would pass but it never went away or got worse. The bike is a 1980 kz 650 ltd

White smoke is typically moisture/water. Since you have an air cooled bike, it's either oil (blue smoke) or fuel (black smoke). Mine actually does the same thing. Looks white but it's either burning a little oil or its running slightly rich.

Is there a way to tell what it is if i cant see the tint. It smells bad if that helps

Pics of the plugs. Could be valve guide seals.
Steve

Sounds like an oil issue. I suggest you perform a compression test and if there is poor compression in one or more cylinders perform a leak down test. The compression test will show if you are leaking compression, and if so, the leak down should help you identify whether or not the leakage is an issue with the rings or the valves. You should be able to borrow the leak down tester and compression tester free using the AutoZone, Advance Auto, or other major auto parts store's free tool loaner program.

If the compression test shows good compression on all 4 cylinders, oil may be bypassing the valve guide seals and being sucked into the engine during the intake stroke and making the smoke.

For future reference, revving the engine with the bike not moving is very hard on the engine. You may see racers do it, but they rebuild their engines very frequently, so it's less of an issue for them. Ed

I was going to guess valve guides or rings, more likely valve guide seals.

I had exactly this on my 'thar she blows' thread, totally irrelevant off topic kz motor tech stuff and of no interest at all to anyone here.

it seems 'white' smoke can be oil burning too, whatever the received wisdom is on this..it surprised me too.

How bad is it to just leave it. There is just enough smoke to see and annoy me

To some degree that depends on the cause. If it's a broken piston ring you may be causing more damage by running it. If it a bad valve guide seal you may develop carbon deposits on the valves, etc. Rather than just ignoring it I would suggest you first run some tests to identify the problem; then decide if it can be safely ignored. Ed

Alright i will check the plugs and go from there