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Re: R90s smoking after startup
Posted: Sun Feb 14, 2021 10:02 pm
by Boudreau
Rob Frankham wrote: ↑Sat Nov 28, 2020 6:00 am
Do you leave it on the side stand after a run... If you do, don't.
Rob
New to airheads/BMW/horizontally opposed cylinders. Is this really something you shouldn't do?
Re: R90s smoking after startup
Posted: Mon Feb 15, 2021 1:41 am
by SteveD
Boudreau wrote: ↑Sun Feb 14, 2021 10:02 pm
Rob Frankham wrote: ↑Sat Nov 28, 2020 6:00 am
Do you leave it on the side stand after a run... If you do, don't.
Rob
New to airheads/BMW/horizontally opposed cylinders. Is this really something you shouldn't do?
If you can, yes.
They can smoke regularly from side stand use or just occasionally. I parked mine using the side stand, amongst hundreds of bikes at a local bike show years back. When it started up, the cloud was enormous! Bike just tootled out of the cloud onto the street leaving dozens of blokes wondering wtf had happened there! 
It's a rare thing though but I use the cs mostly.
Maybe, if when you stop, try turning the ignition off, but remove gloves and helmet before dismounting to the sidestand. Maybe that's just enough time for the oil to drain away just enough? I wonder 
Re: R90s smoking after startup
Posted: Mon Feb 15, 2021 4:14 am
by jkrijt
Have you recently started using another brand of oil ?
On a R100 I used to have, the problem disappeared when I bought higher quality oil.
Re: R90s smoking after startup
Posted: Mon Feb 15, 2021 6:10 am
by Rob Frankham
Boudreau wrote: ↑Sun Feb 14, 2021 10:02 pm
Rob Frankham wrote: ↑Sat Nov 28, 2020 6:00 am
Do you leave it on the side stand after a run... If you do, don't.
Rob
New to airheads/BMW/horizontally opposed cylinders. Is this really something you shouldn't do?
It's something that is best avoided if you can. It's a know 'feature' of airheads that, if you leave the bike on the side stand, it may tend to smoke on start up, normally mainly from the left exhaust. There's never been a definitve explanation as far as I know but the generally accepted story is that, with the bike leaning over, a small amount of oil can accumulate in the lower (left) cylinder behind the piston and a certain amount will find it's way into the combustion chamber, burning off to produce the smoke. It seems to be intermittent and not to affect all bikes. From my own somewhat limited experience (I only use the side stand for short periods or on sloping or unstable ground) there is more of a tendency for it to happen after the bike has been ridden hard and then left on the stand for a period (say overnight). It can be quite alarming the first time it happens.
Rob