The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: decorn33 on September 24, 2013, 06:20:57 PM
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I bit the bullet and invested in a new alternator and new Alpha electronic ignition from Rick at Motorrad Electrik. The installation went OK, the printed directions were pretty easy to follow. The bike starts and runs, I set the idle timing and made sure the carbs were balanced. Two questions arose however that my inexperience cannot resolve: First, I have the timing set so the S is in the window when idling at about 1100 rpm. The instructions call for the F or Z to show up when advanced to 3400 rpm. I see the Z at 2500 rpm and nothing at 3400. Is my idle too fast? I read that it shouldn't go below 900 to keep oil pressure up, and that 1000 to 1300 was a target zone. Second, I noticed due to the fact that the front wheel and fender are off, that my front forks looked out of alignment, (not square to the axle). I put a straightedge against the bottoms and sure enough, about 5mm difference between right and left. I checked at the tops in the upper triple clamp and they are equal. How could one be longer than the other? I have never had them off the bike since I've had it, but I confess replacing the rear axle is a whole lot easier than the front axle.
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My prime suspect would be your fork brace. Let go the tension of that, ease the right leg down so that it matches the left and re-tension the brace.
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There is a rubber washer in each fork tube to cushion the internal parts if the fork extends all the way, a wild guess is that one of them has detiorated and will show up as black goo when you drain the fork oil in that fork .
The rubber washer is around 5mm thick, from the best I can remember .
Again, just a guess, other than that, you'll have to disassemble the forks and see which one is wrong .
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Thanks, I'll do some exploring and see what I find.
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Make sure to strap down the bike when it is up on the lift like that - it is a pain, but they can get kinda tippy like that and we'd hate to hear about it falling off/tipping over while you were pulling on the fork stanchions!
I'd first try the fork brace thing mentioned by Tony - it is the simplest/quickest thing to do. If that doesn't prove fruitful, I would try taking the top caps & plugs out of the fork tubes (will have to remove handlebars from top clamp too - just got a bunch of big, soft rags to put over the fuel tank to rest the bars on) and, once done, reach down and see if you've got the same length fork springs and any preload spacers down in there. This isn't so likely to be the problem, but again, it is quicker and easier to do than the full forks disassembly. If that also proves fruitless, it is likely that the rubber damper buffer has disintegrated on one side (And the other will eventually follow - they have a half life of about 15-20 years, I think).
I started to write up a procedure for replacing & rebuilding the fork damper assembly, but haven't finished it yet. Basically you can look at this thread though - what could be the problem is that the (now red-colored, originally black or creme) damper assemby bumper/topping out bushing has disintegrated (see the pics for the red donut-thingie)...
Does my damper rod assembly look odd to you thread:
http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1371526053
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After double checking my timing and carb settings for the 3rd time and having the same starting symptoms show up again after a short ride, I called Rick at Motorrad and he recommended a new coil which is now on its way. The old Bosch coil wasn't that old, but according to Rick, the symptoms were conclusive to him, so one problem solved.
I also ordered maintenance parts for the forks and they are coming off this week to be rebuilt. Sorry to miss all this gorgeous riding weather, but I see light at the end of the tunnel.
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The old Bosch coil...
...commonly known as the Crack-O-Matic.
When you pull the old coil, wipe it down really well and inspect it for tiny cracks. Usually found on the ends in a circular pattern but sometimes along the body.
This is the Bosch off my 1981 R65. See 'em?
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fi196.photobucket.com%2Falbums%2Faa1%2Fmontmil%2FBMW%2520Ignition%2FOrigCoil01.jpg&hash=3578c2f47619b4416ecaf8fa8528db8c78f645bf) (http://s196.photobucket.com/user/montmil/media/BMW%20Ignition/OrigCoil01.jpg.html)
While you're waiting on UPS, pick up a small tube of Heat Sink Paste at RadioShack. Remove the Ignition Control Unit (ICU) and clean off any old, dried paste and apply enough fresh to get a slight squeeze out all around. Sounds unimportant but several ignition failures far from home are traced to a heat-related issue due to faulty or missing heat paste.
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The topping out Bush that bob mentioned is 7.5mm thick. I'd say that's almost certainly the reason for your forks being a different length.
They are not always this colour but this is what they look like.
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Do you have a multimeter ??
If you do, check the primary and secondary circuits of the ignition coil .
I had a hard cold starting problem that didn't show up until the temperature got to 55 F, 13 C .
The primary circuit had .7 ohms, supposed to be 1.5 ohms .
The secondary circuits should be around 11-13 K ohms .
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I pulled the tank again and disconnected the existing coil in anticipation of the new one showing up from Rick any day now. My coil doesn't look like the one in Monte's photo, but I guess that is just a difference between '81 and '84. It isn't the original coil as I remember replacing it some years ago. It looks OK, but I am still anxious to install Rick's Dynacoil and get back on the road.
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I haven't posted on this issue in a while, basically because I am kinda frustrated at this point. I have new stator/rotor, new Alpha ignition, new voltage regulator, new Dynacoil, new battery, new sparkplugs and wires, and I can't go more than a mile or two before the bike quits on me. Total loss of power, just backfiring/stalling when I twist the throttle - but it will idle beautifully all day long at 1100 rpm. Rick Jones even sent me a replacement ignition because we thought it might have something to do with the ignition advance. It didn't help. The bike will start right up when cold and will accelerate and sounds fine. I can ride it around the block - until it gets up to operating temperature - then trouble. It will always start up after stalling, and it will idle just fine, it just won't accelerate. Not even a little bit. I'm stumped. Any ideas?
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Maybe it's not electrical? Plugged fuel filter, gas tank not venting?
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Have you done anything to the carbs yet ???
My first guess, would be a torn carb diaphragm .
A quick check, remove the carb dome tops and look a the rubber diaphragms .
I had a 1/4 inch tear in one of mine and the bike had a real hard time accelerating .
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It seems like a fuel problem, unless you have faulty new ignition components. You should check for a good spark, however, immediately when the bike starts to die on you--carry a spark plug in your pocket and check for spark on the side of the street. You should also make sure to keep your battery charged while you sort this out. It will be draining at idle, and eventually a low battery could cause you some trouble too.
Also, try reading a plug to help you decide if you've got too much or too little fuel. Clean the plugs before you head out on a test run, and when it sputters, pull em both and see if they look lean (white) or rich (black)
While it does sound like a bad diaphragm, I find it odd that it would rev up when cold but then start to die when warm.
If you went through the carbs right before this problem started, I would make sure that the enrichener discs are not backwards If they are, the bike will run way too rich when up to temp.
AfromNH's suggestion is a good one. Check the fuel flow at each carburetor by removing the bowl and opening up the fuel tap. There is a specified fuel amount that should flow out of each carb. You can probably find it on this website or Snowbum's I can't recall if the carb vents through the small brass standpipe or elsewhere, but you need to make sure that the carbs and the tank are venting. While you are checking for spark on the side of the road, you could also pop off the carb bowls and check their levels. Make yourself a dipstick to keep things quick and easy.
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Thank you guys.
I am pretty convinced at this point that my problems are not involving the ignition system. That was my immediate reaction as the symptoms arose the first night I put in the new components. The bike had been running awhile on the stand, cooled by a fan when it first started acting up.
I have subsequently rebalanced the carbs using the shorting method and with my Harmonizer, and I have checked the timing. Both aspects seem to be proper. As I mentioned, Rick Jones also sent me a second ignition module to test, and the bike acted the same way with that one installed.
I recently replaced both of the diaphrams so they should be fine. I will pop the covers off to confirm that they are seated properly, but I am pretty sure I set them correctly the first time. I will also remove the bowls and check the fuel flow in each carb. I have replacement floats in stock if I need them. Maybe it's time to rebuild both carbs?
I do have an after market in line fuel filter set between the petcock and the "T". I am going to take that out, AND pull the petcock to see if I have any clogging.
I will need to research the venting for the gas tank and the carbs so I know what I am looking for. With the holiday weekend coming up I will have time to devote to investigations. Wish the garage was heated, but hey, I have a garage!
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I'm sure Monte knows the proper saying, but on airheads if you think it's electrical, check the carbs, if you think its the carbs, check the electrics.
To let fuel out of the bottom of the tank, you need to let air in the top. The gas cap on the R65 holds this vent. Try riding around the block, and when the bike starts to bog down, unscrew the gas cap. If it is able to rev again, that would indicate a clogged tank vent, which can probably be shot through with solvent and compressed air.
If you balanced the carbs without taking the bike out for at least a 10 mile ride, they will probably need balancing again. The bike needs to be fully warmed up. It should still run, it just might be a little rough or have a high idle when warmed up
I can't stress enough that you should read the plugs, it is a very easy way to help determine if the carbs are parched or drowning.
A few other carb things:
-if you took the needles out of the slides, you need to make sure that they are set in the proper position. They are adjustable and will substantially affect the mixture on the main jet.
-make sure that your choke cables have slack and that the choke levers on the carbs are fully returning.
-make sure you have no air leaks around the carb boots.
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When the bike dies, if the throttle is shut off does the bike then idle or does it only idle after restarting?
When it dies, check for spark. If there is spark, the problem is then probably fuel.
Crank and ride until it sputters and then open the gas cap. This vents the tank. When back in the barn, remove the carb bowls one at a time and measure the fuel flow. Snowbum says 350 CCs per minute are adequate. He also says both petcocks should flow 16oz in two minutes.
This should be a starting point in determining problem.
Float levels set too low could also lead to lack of fuel at speed. Torn diaphragm symptoms have been a lack of power in my experience.
Try to find the problem before throwing any more dollars at it. I always spend a lot of money without results when I try that solution.
Been there done that lost my shirt.
Bob
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Idle speed won't cause your problems, but I don't like idling them that high. I usually set it about 800 RPM. For the short amount of time my bikes idle, I can't imagine it being a problem, and so far in the 23 years I've ridden airheads, it hasn't been.
Also, I've noticed that a high idle somehow makes shifting more difficult. I have no explanation why that should be since the RPMs never drop that low when shifting, but it does seem to be the case.
In your case it doesn't sound like checking for spark will work, since the bike always starts back up. Checking for spark will tell you nothing.
Here's my thought - you said this problem didn't happen till you installed the new charging system. So why not replace the old components and see if the problem vanishes? Maybe it has something to do with the installation - a wire got pinched and doesn't short out till it gets hot - or who knows? But go back to the configuration before the problem and see what happens.
You need data to unravel this mystery. A scientific approach is needed to collect the data - eyes, ears, multi meter, experiments... however you do it, more relevant data is needed.
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The old Bosch coil...
...commonly known as the Crack-O-Matic.
I have replaced mine with a coil pack from a mercury outboard, for heat sinking purposes I've mounted it on a lump of 3*1" box section (until I can get to the metal recyclers and buy a suitable piece of aluminum)
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In your case it doesn't sound like checking for spark will work, since the bike always starts back up. Checking for spark will tell you nothing.
I fixed up a nighthawk that had a poor battery. It would start and idle fine, but when you started to rev it under load, before the alternator was producing enough juice to run the ignition, it would bog down. You get more compression in the cylinder as you open the throttle, because you are letting more air into the cylinder, and you need a stronger spark as compression rises, which the battery could not provide. I think it's still worthwhile to check for a strong spark when the bike quits, especially if you suspect that there is a problem with the electrical system (intermittent short from a pinched wire).
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So I set out to work through my list:
Pulled off the tank, removed the petcock, cleaned out some sediment I found around the base of the screen and put it all back.
Removed the in-line fuel filter and replaced it with a length of regular fuel line
Pulled the tops from both carbs and checked for problems with the new diaphragms. They were both seated properly and looked good.
Pulled the bowls on both carbs, and confirmed that I had equal fuel in each. Opened the petcock and confirmed flow into each bowl.
Pulled off each carb and confirmed that the jets were not clogged and the slides operated smoothly.
Put it all back together then unscrewed each plug in turn double checked the gap and grounded it against the head. Good spark found at each plug and they were both grayish white - so not too rich.
I ran the engine again until the stall occurred - again. So I had fuel, and I had spark, but the engine would not rev.
So I did the only other thing I could think of. I took out the new Alpha ignition - again, and this time the sender can also, and replaced them with the original Bosch components (which BTW, were working fine when I took them out - they're just old). The engine runs fine now. I don’t know why. Oh well. it's only been since August, and it's 16 degrees out now,considering wind chill. Since I have all winter, I think I’m going to ask Rick Jones to have the Alpha parts bench tested.
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It's my understanding that Rick has replaced, free of charge, a few Alpha systems that had problems. Call him. He wants you to be happy with anything and everything he sells.
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I know - nothing against Rick at all. He had already sent me another ignition module free of charge to test out. It didn't help, so I sent it back. Good guy, but I still want to end up with new ignition that works, and I don't understand why the sending can would have anything to do with the stalling out problem - but it looks like it did somehow.
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It could be a heat related problem, like Wirespokes had mentioned. It's possible to slightly pinch a wire, and when the engine heats up and the metal expands, the pinch gets stronger and causes a short.
Are there any electronic bits in the sending can? Maybe it is overheating. Electronics don't like excessive heat... computer components come to mind, as does the airhead ignition control module. I even had an old cd player boombox that would stop working in the summer sun.