The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: mmf004 on April 13, 2011, 01:46:20 PM
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I have a 83 r65 that runs like top only problem is it quits from time to time. It will restart sometime right away sometimes after a while. It back fires while trying to restart. any ideas?
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Welcome bluebeamer
Sounds like you might have an ignition problem.
Did you check for a spark after it stops ?
If you have no spark one possibility is the ignition module quits through overheating and works again when it cools. The cure is to remove it and renew the thermal paste.
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Can you tell if the entire electrical system quits at this time ?
I had problems with my '81 R65 for about a year, bike would just quit, total electrical system failure .
The bike would sometimes come back to life in a second or two, with a big bang from the exhaust, other times I'd coast to the side of the road and try to get it started again sometimes it would start right up other times it would be a few minutes before I could get it started .
Never found the 'smoking gun' that caused the problem .
I was told by an experienced airhead owner, to take all of the electrical connections on the bike apart, clean and re secure them .
Did that 13 years ago and haven't had the problem since .
No onto a possible ignition problem, the bikes made from 09/80 had a factory electronic ignition installed .
There is an Ignition Control Module under the tank, it has an aluminum heat sink bolted to it, there is a heat sink paste between the module and the heat sink .
Degradation and drying out of the paste can cause the module to get hot and then quit, or act odd .
Another possibility is the OEM ignition coil, the original gray and black coil is known as the 'crack-o-matic' coil, as the plastic case develops cracks and usually during damp conditions causes the ignition to fail .
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Does your '83 have the original Bosch, gray and black, Crack-O-Matic coil? Most peeps refit the Dyna Brown coil from Motoradd Elektrik. I have this coil on both my R65s.
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fi196.photobucket.com%2Falbums%2Faa1%2Fmontmil%2FBMW%2520R65%2FOrigCoil01.jpg&hash=a447270ec5268e3d44ba4a6c971f625f7143d9b3)
Note the very small cracks in the end of the coil. These OEM coils are notorious for failing and raising Cain with the ignition on damp and / or high humidity days.
Where do you hail from?
Monte
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I don't think this will help but the problem rang a very loud bell as I quite often had exactly the same thing with a Kawasaki GT 550 I owned a few years ago. I never solved it but it would appear that the cause may have been ice forming in the fuel circuit somewhere. On stopping, it just melted, always within 10 minutes or less. Never heard of that with an airhead, though.
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I'm reasonably secure in saying that it is in electrical problem in the ignition - which of course still means that it could be the trigger, ICU, coil, and or spark plug wire(s).. The large bang through the exhaust is due to the fact that one or both cylinders have been pumping air/fuel mixture into the headers&mufflers from the ignition stopping, and upon lighting up the engine again it sets off the mixture that is still in the exhaust plumbing.
If you haven't had the ICU off, cleaned and re-schmeared the back side of its heatsink plate with proper heatsink paste in the past few years, then do that first. If that doesn't fix it, move next to spark plug cables and then coil. If you own a multimeter, bring it with you so the next time it conks out on you one the road you can pull the plug caps off (with ignition switch OFF) and test the resistance from one cap to the other. If it is open circuit, it is the coil and//or cable(s) that open circuited on you as they warmed up.
As monte points out, the stock coil - if you still have it- is basically a ticking bomb that will spoil your day eventually. If it hasn't been replaced already, I'd just replace it for peace of mind myself.
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I had the same problem and changed the coil,i used one from a K100,and it's been fine since,good luck.
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Hi mate i had exactly the same problem with mine,it turned out it was a wire had nipped up behind the ignition switch and where the wire runs down the frame,might be worth a look
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Good advice so far and I agree, it sounds electrical. Another place I'd look is the kill switch. Sometimes the switch can jiggle or move just a little and lose contact.
The worst it could be is the hall sensor getting ready to go out completely. Just because you've got spark doesn't mean it's at the right time. The plastic case will deteriorate and eventually break loose from its mounting, and then it's all over. Or they can be heat sensitive and fail after getting really warm, then return to normal after cooling.