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Old 11-12-2011, 07:58 PM   #1
Bull OP
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Joined: Aug 2006
Location: Shelby,NC
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possible smoked airhead clutch

Okay, so this Wednesday i went on a Patriot Gaurd escort ride on my 78 R100 s I used the clutch more than i normally would, now when i'm stopped at a light if i keep the clutch pulled in for more than a few seconds i start to smell an odor coming up from the engine, i dont know what a burnt clutch smells like,so i'm assuming that is what it is, what should be my next course of action. The clutch does not act like it's slipping at all,should i be concerned? Any input would be appreciated

Thanks,Sincerely Bull
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Old 11-12-2011, 08:40 PM   #2
eepeqez
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Quote:
Originally Posted by Bull View Post
...now when i'm stopped at a light if i keep the clutch pulled in for more than a few seconds i start to smell an odor coming up from the engine, i dont know what a burnt clutch smells like,so i'm assuming that is what it is, what should be my next course of action. The clutch does not act like it's slipping at all,should i be concerned?
The odor happens when the clutch lever is pulled in and the clutch is disengaged?

OK, that's not the clutch friction surfaces, since they are not even in contact unless something is very very sick in there in which case the clutch would drag (not release completely).

What it could be, though, is the clutch release bearing, which only makes contact with the pressure plate when you pull in the clutch lever. Is the smell accompanied by a nasty screaming noise? I guess you'd have said so if it was...

It's probably worth having a mechanic (or convenient local ADV person) sniff the smell to see what they think it is before doing surgery to find out what's going on. The technology is all just like a car, it doesn't need to be a BMW specialist or anything.

Getting in to the clutch on an airhead is pretty straightforward. It's basically the same as removing a car gearbox to get at the clutch, except everything is small enough, light enough and accessible enough to be easy to do on your own. If you've ever done a car gearbox, you'll be wishing you'd done an airhead first to learn how it works without having to wrestle it.

Make sure you've got a suitable socket to get at the nuts on the ends of the swing arm pivot. Note that they are inside the frame tube, so the outside diameter of the socket is critical. I had one turned down on a lathe for this job.
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Old 11-12-2011, 08:47 PM   #3
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Yep, the odor only happens when the clutch lever is pulled in and there are no unusual noises involved and no slippage that i can notice.

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Old 11-12-2011, 10:50 PM   #4
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A ryan Pic.
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Old 11-14-2011, 12:53 PM   #5
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any imput greatly appreciated

Thanks, Bull
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Old 11-14-2011, 01:25 PM   #6
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You should inspect the throwout assembly.
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Old 11-14-2011, 01:50 PM   #7
disston
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It sounds like it might be too much free play. If so then when the bike is at rest, in gear. with lever pulled in, the clutch should now be free wheeling and not transmitting power. If you have too much free play the clutch can not release all the way and at rest not transmit enough power to move, especially if the brake(s) are applied. So the engine is working against the clutch disk which is rubbing. Can happen and not make noise, I think.

I don't know this is what you got but thought it was worth a shot. How much free play do you have at the throw out arm on rear of trans and at the clutch lever. Need both, you know.

Other than this I think you have to pull out the throw out pieces and look for problems there.
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Old 11-14-2011, 05:01 PM   #8
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the trans has been leaking at the throwout bearing ive been keeping a close eye on the fluid level and adding as necessary i checked the freeplay at clutch lever and it seems to be about an 1/8th to 3/16th in the morning i will check the throw-out lever at the trans.i talked to a friend today who is an excellent airhead wrench and hes going to walk me through the tob replacement and any other adjustments or repairs i only have to spring for the parts and the barley therapy.Unfortunately im going to have to sell this bike later(braces for the 16 yo wisdom tooth surgery for the 17 yo and the 21yo) however i want to make sure everything is 100% before i do sell it. i bought it from an inmate here almost 2 yrs ago and it's been a blast. i will definitely own another airhead after this one

Thanks, Bull
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Old 11-14-2011, 05:36 PM   #9
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The oil leaking should be easy to fix. There's a seal on one of the thrust piece. The seal is pretty cheap too. All the pieces should be good but if the bearing has a lot of miles on it then changing the bearing is also a good idea. The bearing used to be cheap but I think it went up recently, last few years or so. The design is flawed. They used a needle bearing against two hardened thrust pieces. When the clutch lever is pulled and the throw out arm pushes in on all the parts and this bearing spins at engine RPM between the two thrust pieces. Same thing happens in the /5 4 speed but in the 4 speed the bearing is a ball bearing, works better. As the thrust needle bearing in the 5 speed spins the outer edge of the needles want to travel at a faster speed than the inner edges want to spin. This bearing can and does fail. So it's a good idea to change them once in awhile. I don't think I've every seen any official advice about how often or how many miles but if you have lost the seal back there I would think it's pretty high mileage and I'd change it.

Don't try to take out the rod, part #1. In the pic it looks like the seal, #6, goes on the end of thrust piece, #5. It really goes in the middle of the thrust piece. You probably also need the rubber boot, #7. The needle bearing is #4 Max BMW has it for $30.

http://realoem.com/bmw/showparts.do?...71&hg=21&fg=51


Is there a lot of oil on the shelf under the trans? Is the smell you have like burning oil?
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Old 11-14-2011, 06:10 PM   #10
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thank you for that info disston,it doesnt smell like burning oil to me but i could be wrong, since changing over to semi syn little leaks are popping up that need to be addressed the bike will get a thorough going over in the next several weeks.

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