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Old 11-12-2009, 11:04 AM   #1
More_Miles OP
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Airhead R100 horrible smoke at cold start

Inmates! Opinions solicited!

Specs:
1983 R100RT
Stored overnight in the garage
On centre stand
Fuel valves off

Symptom: Left (when astride the bike) cylinder burns clean at start up but smokes FURIOUSLY after about 1-2 seconds of running. Right cylinder burns (relatively) clean upon start up.

If I was storing it over night on the side stand, I could buy the "oil lays in that cylinder" song. But I'm not, and it's sitting upright all night. It DOES clear, and if started up later on (i.e. warm start) no problem. This just started a few days ago. It also seems to be using a bit of oil. I know, it's a boxer, live with it...

My thoughts, and feel free to tell me what an idiot I am for this line of reasoning:

Over night, everything is cold, and a valve guide or valve stem contracts. This opens up a clearance into the cylinder. At start up, things are relatively dry and away it goes. Oil gets pumped into the top end (do boxers actually have "TOP" ends?) and out this opening into the combustion chamber. Smoke like hell... Warms up, things expand, seals back up and Bob's your uncle. Also, cold is in the -5 degree C range...

Tonight when I get home, I'm going to pull the plugs to take a look. I also should get a compression tester sometime. I'm wondering if at 107000 km with an unknown engine I'm due for a top end rebuild.
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Old 11-12-2009, 11:31 AM   #2
Pigford
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If you're lucky, it may only be the valve guide seals

Or at worse, the guides!
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Old 11-12-2009, 12:22 PM   #3
SOLO LOBO
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Quote:
Originally Posted by Pigford
If you're lucky, it may only be the valve guide seals

Or at worse, the guides!
No valve guide seals on boxers....
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your bike is suitably dirty. Well done.
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Old 11-12-2009, 12:49 PM   #4
Mista Vern
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This sounds too simple, but in many cases where there is a mix of cool weather and humidity and the bike has not been ridden enough to get all the moisture out of the exhaust system, it will blow smoke-like vapor like a sumbich until all the moisture in the mufflers is gone.

Odd thought, but could well be the case, especialy if this seems to be a brand new problem.
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Old 11-12-2009, 01:04 PM   #5
bpeckm
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That's a thought!

See if you can tell whether it is smoke, or steam. Though why one side would have more condensate than the other....

If it is oil, my guess is that it continues to burn the same amount on the left side, but when it is hot, the oil is burned up more, leaving less to "see"....

Your idea of pulling the plugs should give you additional clues/information..

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Old 11-12-2009, 01:07 PM   #6
outfit
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You only put oil in upto the halfway mark between bottom & top mark's on dip stick? Otherwise it'll just burn off any oil above.

Karl.
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Old 11-12-2009, 01:46 PM   #7
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Quote:
Originally Posted by outfit
You only put oil in upto the halfway mark between bottom & top mark's on dip stick? Otherwise it'll just burn off any oil above.

Karl.
Really? So I shouldn't have bothered just topping my oil up?
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Old 11-12-2009, 02:15 PM   #8
More_Miles OP
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Quote:
Originally Posted by outfit
You only put oil in upto the halfway mark between bottom & top mark's on dip stick? Otherwise it'll just burn off any oil above.

Karl.
I should have mentioned that the oil level is just above the low marker on the dipstick and due for a change. It's getting that and a filter tomorrow. Almost time to put it up.
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Old 11-12-2009, 07:15 PM   #9
WooHoo
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I have the same symptoms (assuming it's oil and not water burning) with my 89 R100GS (and previously on /5's.).

I am pretty sure in my case it's caused by the way I park my bikes....

When I get home I ride down my drive and shut off the engine and gas and prop the bike on the side stand while I open the garage, then I push the bike in and haul it up on the centre-stand where it sits till next time.

About one time in two she'll smoke on startup from the left.

I always thought the chance occurrence was a result of:

1. The oil level.
2. where in the stroke the piston ended up sitting ( maybe more TDC = more oil to dribble down ); and
3. where the ring gaps happened to be at that time.

You may have a totally different issue but while I noted you said you leave it on the centrestand overnight, you did not say you didn't use the side stand as part of the parking process. If you do, this may be your issue as well.

I agree it can be real embarrassing when you billow smoke like the Queen Mary, especially when parked bum to curb in front of your favourite cafe with the nice alfresco dining....

I've heard it recommended leaning the bike to the right for a few seconds after shutting down the engine prior to parking to avoid this. I tried it but didn't really help me much.

Ta.

Tim
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Old 11-12-2009, 10:37 PM   #10
Rob Farmer
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I had exactly the same thing on my 100/7. It stood for several years at one point in it's life and had some corrosion on the bore that would allow a small amount of oil to sit in when the bike stood overnight. Firing it up resulted in a cloud of smoke that lasted anywhere from 30 seconds to a minute, once cleared the bike would be fine all day. I honed the bore out a couple of years ago, re ringed it and it's never happened again.

unfortunately you have nikasil bores so you may not be able to hone them.

Rob Farmer screwed with this post 11-13-2009 at 08:24 AM
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Old 11-13-2009, 07:45 AM   #11
More_Miles OP
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Pics and vids

Inmates,

A day late and a dollar short but here we are.

These are the plugs. Left is left and right is right. I'm going to pop a new set in tonight.

From Motorcycle Bits
An oil check prior to starting up. Yes, it's low, getting changed tonight with a new filter.

From Motorcycle Bits
It was about -1 degree C this morning when I headed to work. Here's the proof!

From Motorcycle Bits
Now, before anybody makes comments about my riding gear, it's the best I could come up with at this time. Here's the video of the cold start, after sitting over night in the garage. Also, please excuse the mess, if you are coming to see me, come any time, to see the house or garage, make an appointment!

Questions have been asked about my parking style. Sometimes I shut down on the side stand for a couple moments while I open the garage. Sometimes I let it idle on the side stand while I do the same. I always run it into the garage under power since there is about a 1 foot rise and a 3 inch lip at the door. Okay, so I'm lazy...

Now that you can see the symptoms, thoughts? After smelling the exhaust, it's doesn't smell like rich, vapour laden exhaust. It also doesn't really smell all that much like oil burning...
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Old 11-13-2009, 07:53 AM   #12
sharkojoints
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Does that smoke still happen if you don't use the choke?
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Old 11-13-2009, 08:02 AM   #13
bpeckm
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Sure looks like oily smoke to me..... and the left plug has deposits which would be consistent with oil burning.

Do a compression check.

You might also want to do a simple check at the "output" of the crankcase relief: there is a tube that dumps into the right air tube: pull the airtube off the right carb/rightairboxiside, and stick your thumb over it while the bike idles. If you have a lot of really oily air there, it could be the problem... the oily airmix is being sucked into the carb(s). Pull the airtube off the left side: is it oily over there?

I am thinking that if the onset was sudden, you may have a broken ring. It could also be valve guides, but I don't think that you would be burning that much oil with a bad valve guide.....



Both sides are smoking, though it appears that the smoke is thicker at first from the left.. if you block the left exhaust with a rag, does the right side sound the same.... I am wondering if most of the smoke is pushed over to the left side because the right exhaust is sorta plugged with oily-ness....
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Old 11-13-2009, 08:20 AM   #14
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Quote:
Originally Posted by sharkojoints
Does that smoke still happen if you don't use the choke?
Nope. On the other hand though, the only time I don't need to use the enricher is when it's warmed up. Current temperatures are such that it need all the help it can get. So this doesn't tell us much... Is it because it's cold or because the enricher is on... Feh...
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Old 11-13-2009, 09:37 AM   #15
More_Miles OP
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Quote:
Originally Posted by sharkojoints
Does that smoke still happen if you don't use the choke?
Perhaps confusing the issue now... Just zipped into town for lunch. Started to smoke when I started it, I killed the enricher and kept it going with careful application of the throttle. The smoke petered out and stopped...

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