Valve guides? - unlikely to VERY unlikely.
Rings? Likewise at 20k
Leaking injectors - at 20k they're a long way from worn out. If leaking bad enough to cause it to burn oil at startup you should be able to smell fuel contamination in the crankcase oil and maybe even see the level rise. If so run a bottle of "Fuel Power" injector cleaner through it and then change the oil again.
While on the oil change subject, NEVER fill above 1/2 way on the sight glass on the center stand on level ground. Better yet stop at 1/4 of the way up from the bottom of the sight glass. More than that invites smoky startups (but it usually stops shortly down the road). If full to the top (or more) on the center stand increased oil consumption is likely.
If a leak down and compression test are negative/look good then the chance of a bad head gasket is slim.
Now... If the white smoke smells of antifreeze then it's a head gasket or cracked head. Still, both of those are unlikely at 20k on a brick motor and will probably show up in the compression test.
You'd also be able to observe bubbles in the radiator as it warms up with the cap off (take it off before starting when engine is cool)
I'd really lean towards over full oil before anything else.
Other than the stumble does it run smoothly?

 

Thanks for the response RAC, it started Before I changed the oil. I think I’ll do my tests and then see what I have.

 

I once saw a post advising corrective actions to remedy this type of problem. He described it as the 'Italian method' or something like that. Go out and ride it hard for a while was his recommendation.

I bought at auction a 2001 K1200RS that smoked as you described. I took it out for an exhuberant ride. The smoking problem went away and has stayed away. I'm only guessing, but perhaps an oil ring gets a bit stuck.

 

Ok Thank you, I will do that

 

Ah, the old "Italian tune up" love it

 

Assuming the oil is creeping past the rings and into the combustion chamber when using the side stand, then park it on the centerstand instead. After it cools down, use the side stand. This was a fairly common problem with the brick engines.

 

Both my brick and my oilhead blow oil smoke on startup, but it stops after a short time. My K100 did too. White smoke suggests coolant. This and the presence of bluish smoke once warm makes me think head gasket failure. Not a bad job on a brick.

 

Yes, that’s what I’m thinking but im glad you say it’s not a bad job on a brick. That helps

 

Hi. I had the same “problem” several years ago. My k1200RS was standing at the side stand when I was at work. After starting the engine it was as you’ve described: white smoke, then blue… It was a shame to drive it. But after 3-5 km problem gone. Since then I never left a bike at the side stand for longer time and never more I had this “problem”. Now my bike has 71000miles, still the fastest on the traffic lights

 

Welcome to the forum. It also helps to not fill too much oil.

 

So here's a mechanical explanation of why this happens, and why it can inexplicably start and stop without any real engine mechanical problems being present. First off it can be a problem with any engine that lays on its side and where hot oil can accumulate in the bore at the bottom of the piston after shutdown. Especially true when inclined toward the cylinder head after shutdown and that's why it's not uncommon for brick K's and the R's (especially the air heads) to do this when left on the side stand. Engines also develop a tendency to stop in the same place. If that means a piston, or two, are at the top of the bore at shutdown then more oil can accumulate and increase the likelihood of the startup smoking.
Now, one would suppose that good sealing rings would prevent the problem, and most of the time that is true. However, most people don't realize that the piston rings will rotate/spin in the piston grooves over time. In some engines, probably due to slight out of round bores, we're talking tenths of thousandths of a inch so not much, the gaps of the rings will align themselves with each other. As they move around the piston over time if they have a tendency to end up along the bottom side of the bore the hot oil that accumulates at shutdown more easily weeps through the ring gaps, accumulates in the cylinder and has to get burned out at startup.
This is exaggerated in the bricks and flat twins when parked on the side stand, when the oil level is kept higher, and when an oil on the thinner side is being used. In all these cases there's nothing really wrong with the motor.

 

Since you’re new to the bike, don’t leave it in the side stand. Leaving it on the side stand will cause this since the head and valve are downhill. The oil will leak into it that way. If the smoke goes away after a few miles that’s your issue. I have 123000mi with no valve seal issues and it still cranks 198lb of compression. Hope this helps.

 

I’ve owned the bike only for several months and put over a thousand miles on it. Always had it on the side stand. No smoke. Then one day it was very dramatic, lots of smoke, white, then bluish

 

... and just like that, it'll go away. That's typical.

 

My example relates to an airhead, an 81 R100RS. Rarely smoked on startup. I was at a motorcycle show, parked on the sidestand amongst 100's of bikes. Show finished, riders leaving. People heading to the exits. I was already seated on my bike and started it up.

I expect every single one of those riders looking for their bikes took quite a bit longer to leave than they expected. Thick white smoke completely enveloped the whole area. I putted out amongst the cloud...and left them all to blame the two stroke!

In 100000km of riding that bike, it did it 2-3 times.

My 83 K100 did it too!

 

Same here (K1200RS/2004)...parking on side stand for a while and on startup you get bombarded with good advice how to fix your bike .. good way to meet new people.

 

Well, to all those who stated that these bikes smoke when left on the side stand. YOU ARE ALL CORRECT! Now, I removed a plug and did a compression test and it is around 210 psi. Now that I know not to leave it on the side stand, I am chasing down a mis. After the bike is warmed up it has a stutter when I try to rev it, but at lower speed the stutter or mis is there. I’ve changed the oil and put new plugs. In and gapped them. The bike had a mis before I did all this.
Thanks to all the advice I recieved

 

Have you replaced the air filter? Look for obstructions in the inlet tube too, field mice and such like building nests it use it for nut storage. Too, if you’re going to keep the bike for any length of time I highly suggest getting a GS-911 diagnostic too to read codes for any issues. It’s not cheap but way less than a dealer at over $100 hr for service……. If they will ever look at it. I recommend the WiFi model. The cardholder is a chore but you’ll need to learn the procedure eventually. While the panels are off look around for loose vacuum hoses to the throttle bodies. I had a vacuum hose off that the factory never installed, so you never know. Also since the tank needs removed drain it completely to rid it of any water accumulation. Keep us posted.

 

Take off the plastic spark plug wire cover and start it in the dark. Might have a wire on its way out. On the other hand, mine was low miles and had set a long time. Best thing for it was a couple tanks of fuel with a good injector cleaner .

 

1) 90% side stand consumption ;-)

2) If the oil is creeping past the oil rings there's a easy way to check that. Get yourself one of these cheap USB endoscope cameras and have a look at the piston top. it should be regularly covered in coal/soot ... if you see clean "washouts" that's the oil washing away the soot. Likely to fix itself. Happens mostly on old bikes with little kilometers.

3) Valve seals brittle; happens mostly on old bikes with little kilometers.

4) BMW "oil farts" ... almost all BMW cars in the 70s/80s did it from new when you were getting off the accelerator ... again, valve seals and a vacuum building up when decelerating ...

5) Love the 'Italian method' .. haven't heard of it for a while!

Hope that makes sense (and not lost in translation)

 

When the bike has been on the side stand for a length of time, if you lean the bike to the right side for 45 - 60 seconds before you start the motor, the smoke will be greatly reduced.

 

oil level too hi -