The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: bobo on October 10, 2008, 06:54:17 PM
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Hi,
Perhaps someone can suggest a fix. After storage last winter, my 83 R65 has idled very rough, like it might just be running on one cylinder. It runs ok at higher speeds, but barely runs at lower speeds. With the choke on, it idles almost ok. So my thought was that this was the idle jet and it took that out and cleaned it. When that didn't fix it, I took the carbs off the bike and cleaned them really well and checkewd very careully that nothing was blocking idle jet.
By the way, in the course of checking this out I found that I had a cracked dual coil. It worked ok, but had nfinite resistance. When I inspected it, there was a crack. I imagine it would have cut out if it got wet. Meanwhile, my 83 R80RT is loaning the R65 it's metal coils.
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Fresh fuel in the tank? Gummed up fuel lines? Checked spark plugs? COILS?
THE place to get your new R65 coil is from Motorrad Elektrik. Rick Jones is the hoss.
http://www.motoelekt.com/index.html
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I did think of these things. There is fresh fuel in the tank. The fuel lines are not gunked up because there is plenty of fuel in the float bowls and I did first try to flush them by turning on the petcock with the bowls off and moving the floats up and down and there was plenty of flow. Doesn't seem like any problem with the coils (and wires) as the resistance is right, and as I said, I have the good coils from the R80 in there now. I thought it might be the spark plugs as they were a little black, however once I went on a 20 mile ride where I kept the speed up, they were the appropriate grey. I also swapped in anotehr set just to be sure. I have also checked the valves just to be sure the adjsuting nut hadn't come loose on one of them.
My thoughts are that somehow there is something clogging the idle jet that I missed (even though I went through them twice, but the problem is really in the area where teh idle jet is functioning) or it could be the advance sticking. I haven't really been under the front cover before. Is it possible that the advance is sticking i.e. that it is stuck out at the full speed position and would it cause this?
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Do you have a timing light ? That would tell you if the spark was too advanced without taking the cover off, but if the idle speed is very "iffy" and changing alot from running rough then it may not be such a good indicator either. Usually sticking advance weights happen when the bike has been running at higher RPMs and then doesn't want to go back to idle when coming to a stop light, etc. The problem is very likely in the carbs, or possibly the horns/piping from the carb to the head. If you are getting an air leak in there that could cause bad idle. Perhaps when you were in the carbs initially you dislodged something that then floated back in to clog up the idle jet or passageway. Also, when you put the carbs back together, if the jet needle isn't sliding up and down or isn't seated properly (might be raised out of position, or the clip might not be in the same position as the other side)? could also cause a messed up mixture on one side.
Can you tell from the smell of the exhaust if one side is running rich ? I Fyou crank the engine over to start it (but do not let it start - perhaps pull the plugs out but leave them grounded on the cylinders) can you tell if you are getting fuel to both cylinders ?
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Thanks, I will try the timing light. I have one somewhere, although I haven't used it since back when I had a car w/o electronic ignition.
The rough idle is at low speeds as well and is consistent. Since it runs ok at higher speeds and is not variable, I don't think it is the main needles - the problem seems to be more in teh zone before the main needles start to open up.
I checked for an air leak by spraying starter fluid around the air tubes.
I will see if I can smell a difference between the cylinders and then perhaps take the carbs apart again.
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I had similar problems several years ago. I had several issues so I can't definitively say what the final solution was but I had a bad coil and a bad plug wire. I cleaned all of the electrical connections under the tank, replaced the coils and wires and maybe some other things and the problem was cleared up afterward.
To determine which side is failing just start it up while it is cool and just let it idle. As it warms up you can feel the warm exhaust on the good side.
Good luck,
Neal
p.s. Did you spray the buttons on the tops of the carbs when you tested the carbs? Not sure if that could cause those symptoms or not. Are the carbs level? Sometimes they get canted a bit and it causes some weird float level problems.
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Boy, I know the feeling!! My 48k miles, '80 R65 wouldn't idle below 2k, the left header glowed red at night and it would burp and pop from time to time. Seemed to get good at higher RPM. I was afraid to drop RPM at lights or in stop-n-go traffic cause it might die.
Discovered the following,
- the tubes connecting the Bing to the intake manifold were getting old and leaked (therefore the cherry red glow), replaced with new ones (discovered with carb cleaner test) ==> improved
- the intake manifold on one side had a small leak, loosened it with a strap wrench, then tightened them both using an anti-seize compound, (discovered with carb cleaner test) ==> improved
- over the winter a little field mouse had set up his bachelor pad in the airfilter and the lint and grass had reduced airflow, evicted the sucker ==> a little smoother
- plugs were indicating poor combustion. Put in a new pair ==> we're getting there
- Synchronized the carbs, set idle at 1200 RPM ==> got a steady tic-tic-tic
- Went back for a second round, began with valves, they were too tight, probably reduced compression and made engine sensitive to variation in idle with engine head temperature. Synch'ed again
Result: RUNS VERY WELL. Don't ask me how everything got screwed up.
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;D ::)
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So I think I have this figured out now. I started it up with my carb sticks attached and found that the left carb was drawing a lot less vacuum, so the problem must be in there. I took it off and took it apart again. This time in addition to paying close attention to the idle jet which was clear from the first two times, I also removed the idle mix screw and cleaned it out. It looked like it was gunked up. I had previously not thought about this as I don't usually mess with this to avoid screwing up the idle mix setting. It started up easier after this, but I ahven't taken it for a ride yet to test for sure.
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Did you check your pilot jets? I think that's the right term. They screw up into the carburetor from the underside, after you remove the float bowl. They can get gunked up too.