The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: R80rider on April 26, 2015, 09:46:56 AM
-
Several months ago, my 1986 R65 developed an intermittent but predictably repeatable misfire. It is repeatable in the sense that starting normally and riding 35-40 miles at highway speed seems to bring it about every time. When the problem manifests, I notice a little extra vibration in the handlebar and the foot pegs. There is no audible backfire, nor is there much loss of power. Also when it occurs, I can shut the cycle off and wait a few minutes and when I restart, the misfire is gone. Both my brother and I who own a few of these older airheads have looked into this matter along with a very experienced airhead mechanic.
I am in the fortunate position of having a 1987 R65 that I can use to swap known good parts from and have done this in a fairly methodical effort to isolate and isolate this issue. To date, the following parts have been moved over one-by-one from the donor R65:
1. Spark plugs and spark plug wires
2. Coils
3. Ignition controller (under the tank) unit
4. Ignition trigger (bean can)
5. Headlight relay (under the tank)
6. Voltage regulator
Additionally, we have checked the ground wire on the dual coil, checked the valve clearances, and set the timing. The problem has persisted through several tanks of fuel, and none of the steps listed have changed the symptom as described above in any way. It should also be noted that the cycle ran fine for several thousand miles before this problem occurred. The first time it was noted was on a trip from Chicago to Phoenix while riding through Texas.
When it occurs, vibration can be felt while riding. It was suggested that an inductive timing light be carried with me while test riding to allow both sides checked when the misfire starts occurring. I have done this and can verify that the light strobes confirm a misfire on the right side of the cycle. I cannot completely rule out that it might be occurring on the left as well but that has not been empirically observed.
With regard to the instruments and warning lights on the cycle, the tachometer does not appear to bounce and I have not noticed any flickering or other unusual behavior from the warning lights or any other electrical instruments on the cycle.
The cycle is stock with no third party ignition or carburetor modifications. Both these systems are set to factory specifications.
With regard to the donor 1987 R65, it is running without issue using the components swapped out of the problematic 1986 R65.
At this point, I am looking to this forum for help in resolving this issue.
Please feel free to ask questions and I will make every effort to answer them as quickly as possible. I am open to suggestions no matter how obscure they might seem. My hopes are that someone has experienced this or a similar issue and might have the solution or possible solution in hand.
Thanks in advance and I look forward to hearing back from you.
-
My R65LS has very noticeable vibrations at the footpegs and handle bars.
I've had success "tuning" the RPM's they occur at by adjusting (fine tuning) the carb sync
As you have tested all the ignition system parts with no effect on the behavior, it would seem to point to this being a carb tuning issue.
The R65 vibes (behavior) nothing like the R100GS, R100RS's, R80G/S and R60/5 that I have owned in the past... completely different animal in terms of vibrations
Also, drop the float bowls and look for a lens of water in the bottom of the bowl.
-
Sounds like you have approached the problem in a thorough and logical manner with the parts substitutions. Ignition would therefore seem to be ruled out as the cause of the misfire. Short of something very strange that would cause a loss of compression that really only leaves carbs. Are the carbs the same on the donnor bike which would allow a swap ?
-
Thanks for both of the replies! Yes, the carbs are the same. I suppose if I am going to swap them, I should do one at a time to isolate the problematic carb.
Any ideas what would change in the workings of a carb at 40+ miles that would cause this issue?
-
I had a somewhat similar issue with my '81 R65 about 22 years ago, but I had a complete loss of the electrical system when this happened .
At that time I was told to go through the electrical system and pull apart the electrical connectors and check the ' pins ' for security and corrosion .
Found a few that were not locked into the plastic connector body .
Never found the ' smoking gun ' that was causing the issue, but it hasn't returned .
I also had a failing ignition switch give me almost the same conditions a few years later, finally one of the contacts broke off and you could hear it rattle around inside the switch after I removed it and shook it around a bit .
I don't know if the mono shock bikes are the same as the twin shock bikes in this matter, but most of the grounds for the bikes electrical system are ganged together at connect to the frame at the voltage regulator attach bolt .
May want to check that connection for security, corrosion, broken wires, etc .
I ran an extra 10 gauge wire from this point back to the battery negative terminal, just so grounds are not an issue in the future
-
Thanks Bob! I will definitely try adding the ground wire.
Something that I want to ensure does not go unnoticed is this:
If I take the cycle on the same route, the "misfire event" occurs at a predictable location at around the 40 mile mark. I have come to recognize the landmarks in that area and know the misfire is about to occur.
So something seems to happen every time when the cycle hits a certain temperature or some other variable I have not considered.
-
Only thing that comes to mind, is heat sink paste between the ignition control module and it's heat sink .
But the later bikes had the control module riveted, or bonded to the heat sink, so you may have one of those types .
-
It's bizarre that the symptoms occur with such predictability at the 40 mile mark. You would think any temperature related cause would make itself know sooner.
To re-cap you a have a misfire which seems not to be ignition related as substitution of the ignition components makes no difference. In truth all of the ignition system has not been substituted because the ignition system is dependant on the ignition switch, kill switch and wiring harness. But I think they can still be ruled out on the grounds that any fault with the ignition system wiring would have an affect on both cylinders and as far as you know only the right cylinder is affected.
So back to carbs. What would change in the workings of a carb at 40+ miles that would cause this issue? Logically it would have to be a significant change in mixture strength but as to the cause, I honestly can't think of a mechanism that would occur with such predictability.
I guess you have to defeat this problem with logic and start by showing if it is carb related or not by a simple substitution. If the carb is shown to be the cause only then delve deeper to determine the exact cause.
-
We have one that is riveted and one that the heat sink comes off so you can apply the paste. Like you, we thought that could be the answer, but it did not change the symptoms. We also swapped the one from the '87 and it also resulted in no change.
Really appreciate the input!! I'll let you know the results of the ground wire addition.
-
In the first post, the comment is made that the misfire can be confirmed with using a timing light on the right cylinder .
Carb issue will not give an ignition system misfire indication .
-
"In the first post, the comment is made that the misfire can be confirmed with using a timing light on the right cylinder .
Carb issue will not give an ignition system misfire indication."
That is what we concluded also which is why I asked if there is a logical reason to visit the carbs?
-
I questioned going to the carbs myself as well .
There is no easy way to troubleshoot this problem .
The only two things left in the electrical system that are swappable between bikes, is the kill switch and ignition switch .
After that, it's a wiring harness .
Have you checked the fuses for condition and security, the OEM fuses are the cause of some electrical issues, the spring tabs that hold the fuse sometimes don't do a great job .
I've replaced mine with a blade fuse holder .
Just adding possibilities to an ignition system issue that I've seen or been told about over the last 4 decades, a tachometer is connected to the primary circuit of the ignition system, an issue with the tachometer or the wiring to it can cause ignition issues .
I know you've already stated that you see no tachometer indication issues .
-
Definitely going to run the ground wire and check the fuses and fuse holders as these are things we have not tried before and are great suggestions.
We really think this is occurring on just one side of the cycle. If you have any other ideas of what electrically would only affect the firing on a single side, that input would be very helpful.
I will update you once we have tested with the ground wire and inspected the fuses and fuse holders.
Any other suggestions are always welcome. We would really like to get this resolved.
Thanks!!
-
To rule out the ignition system cant you simply swap the plug wires at the coil without swapping the wires at the plugs. (or swap at the plugs and leave the wires alone at the coil )
If the miss does not swap then you know you have a problem at the head.
compression or fuel
Sounds to me like you have a carb issue.
Have you put manometers on it and tried to see if the carbs will balance at the higher RPMS's
-
Sorry for the long delay in posts.
Following the suggestion that the plug wires be swapped, this was done last night. The problem took a some extra miles to recur but when it did the symptoms were the same and only on the right side (same as always).
Unless someone has a further suggestion, it seems that the ignition system is not the problem.
A few of you suggested that it might be carburetion on the affected side. If anyone can explain what might change in the mixture or engaged jets during a ride of this duration, it would be greatly appreciated.
I am now more inclined to think it might be mechanical with something sticking or some other dynamic changing when it hits a certain temperature.
Looking for continued help and thanks in advance!
-
Looking back over the whole thread I at first thought you had eliminated ignition through parts substitution which was why I suggested it might be carb related. But I missed the comment about being able to identify the misfire with a strobe lamp
It was suggested that an inductive timing light be carried with me while test riding to allow both sides checked when the misfire starts occurring. I have done this and can verify that the light strobes confirm a misfire on the right side of the cycle. I cannot completely rule out that it might be occurring on the left as well but that has not been empirically observed.
That places it firmly with the ignition system as you are saying the strobe identified missing sparks. What is puzzling is that the electronic tachometer doesn't register the misfire.
So it's an ignition problem; a marginal one where it just fails to generate a spark at the plug but still fires the tachometer. Just a thought as a temporary test - you could try closing up the plug gaps a few thou to see if that helps by reducing the demands on the ignition system. If it does you still need to identify what is causing the poor spark but you will have learned something. It's not necessarily true that any ignition related problem should affect both sides because conditions in the cylinders and therefore threshold spark energy demands are not absolutely identical. If the the spark energy is gradually reducing for some reason it's perfectly possible that one cylinder will show it up before the other.
-
Thanks Barry,
As you no doubt noted, the coil wires were swapped last night prior to the ride in an effort to either get the problem to move from the right to the left side or rule out further investigation of the ignition system.
The plugs and wires have been both changed and swapped.
It would seem that nothing is left but mechanical unless I am still missing something.
Some have suggested carburetion but am unclear on what could/might change in the physics of a carburetor from say mile ~10 *fully warmed up* to mile 50?
-
It's a puzzle. If I understand correctly you actually saw an ignition misfire when using the strobe lamp and that corresponded with the symptoms that the engine was displaying. So did the ignition misfire or not ? If it did then the puzzle is why one cylinder and not the other especially after changing the ignition components around. That's what I was trying to explore above by suggesting that each cylinder could have slightly different ignition requirements and a failing ignition system might therefore hit one cylinder first. Closing up the plug gaps costs nothing and is worth doing even if it only serves to dismiss ignition as the source of the problem.
It is hard to conjure how a carb could cause this problem in such a predictable way.
On the mechanical possibilities did valve clearances get mentioned and checked ?
-
By chance, when this misfire occurs, are there any high voltage cables overhead, or any other large electrical transmission equipment near by ???
My mother has a van, that if she takes a particular route that takes her under some low hanging 400 KV transmission wires, all the lights and cautions on the instrument display illuminate and no throttle response if additional throttle is added .
It's a Honda and the dealership can't find anything wrong with the vehicle, there are no faults generated in the vehicles computer to do any troubleshooting .
-
Thanks for all the input.
Yes, the misfires were verified with a timing light and did not move with the coil wire swap. The valves have been set at least twice since this began happening.
While it cannot conclusively be said that there were never any high voltage line, the misfire seems to be more based on time ridden/miles than location.
Both spark plug wires have been replaced and now swapped.
Spark plugs were refreshed since this started happening.
The gap of the plug on the affected side could be closed, please explain how this might help?
Any other ideas, no matter how obscure are invited.
-
The gap of the plug on the affected side could be closed, please explain how this might help?
You could be having an over all ignition system failure and it only shows up on the one side because it has more compression or leaner air /fuel mixture requiring more demand on the ignition system
Closing up the gap will let that cylinder require less voltage to spark and the misfire may move to the other side ruling out any other problems with carb or compression.
After that I think you need to hot wire the the ignition system
Or you could hard wire a volt meter into the ignition system in different location and watch the voltage
I have a feeling you have a electrical connection heating up and getting high resistance in it. When you stop and let the system cool down a bit it closes.
You can also feel the connectors to see if one is getting hot
I think the time it takes to act up is to long to be a carb issue and you have confirmed that you are loosing spark when the problem happens
-
This clutching at straws but it's just occurred to me that there is a small theoretical difference between the two cylinders as far as the ignition system performance is concerned. A dual output coil produces sparks of different polarity with the spark travelling from the centre electrode to the side electrode being more efficient than the other way around. That means one spark plug is more efficient than the other at creating a spark and in very marginal conditions that might just count.
There is a way of testing for polarity but it's easier to just swap the leads. Did you try swapping the ignition leads over but only at the spark plug end leaving the coil connections alone.
-
My 1980 r-65 gave me a problem last sunday the difference being my miss was both cylinders, I experienced a battery failure and as power from the battery became less and less available the miss got more and more pronouonced until the battery went right flat even the neutral light would not come on. I charged the battery for 5 minutes and started and got home to have it fail again at the shed door 3000 yards and required a second charge to get in the door. A new battery is on the way very pricey little bugger, anyone know if a YB-18L-A will fit in the frame CCA is better on this size than the no longer available in my area proper sized battery.
-
I think you will find that battery a very tight fit in the battery tray if it goes in at all. The critical dimension is the depth because of the limited gap between the air box and the rear mudguard. The stock battery is approx. 80mm deep and the data I have on the YB-18L-A is it's 90mm deep. It may just squeeze in but might require the tray to be modified.
-
I think you will find that battery a very tight fit in the battery tray if it goes in at all. The critical dimension is the depth because of the limited gap between the air box and the rear mudguard. The stock battery is approx. 80mm deep and the data I have on the YB-18L-A is it's 90mm deep. It may just squeeze in but might require the tray to be modified.
I'll go to the landfill later today and look for an old one to try in the frame to check the size opens at 1:00pm local
-
The YB-18L-A battery is too large to fit in the battery tray of an R65 .
The dimensions of the YB battery are 11 inches in length, 7.1 inches wide and 6.4 inches high .
The battery that fits the R65, is 7.13 inches in length, 2.99 inches wide and 6.69 inches high .
-
My 1980 r-65 gave me a problem last Sunday the difference being my miss was both cylinders, I experienced a battery failure and as power from the battery became less and less available the miss got more and more pronounced until the battery went right flat even the neutral light would not come on. I charged the battery for 5 minutes and started and got home to have it fail again at the shed door 3000 yards and required a second charge to get in the door. A new battery is on the way very pricey little bugger, anyone know if a YB-18L-A will fit in the frame CCA is better on this size than the no longer available in my area proper sized battery.
I think you may want to check your charging system.
It sounds like your battery is taking a charge.
Symptoms of battery failure are generally slow or no cranking at all after you turn the key off and try to restart.
A battery can also short out causing heavy load on on the charging system that will reduce system voltage to a point you can have a week spark.
But that doesn't sound like what you are having because if it was you would not be able to charge it up and restart
-
My 1980 r-65 gave me a problem last Sunday the difference being my miss was both cylinders, I experienced a battery failure and as power from the battery became less and less available the miss got more and more pronounced until the battery went right flat even the neutral light would not come on. I charged the battery for 5 minutes and started and got home to have it fail again at the shed door 3000 yards and required a second charge to get in the door. A new battery is on the way very pricey little bugger, anyone know if a YB-18L-A will fit in the frame CCA is better on this size than the no longer available in my area proper sized battery.
I think you may want to check your charging system.
It sounds like your battery is taking a charge.
Symptoms of battery failure are generally slow or no cranking at all after you turn the key off and try to restart.
A battery can also short out causing heavy load on on the charging system that will reduce system voltage to a point you can have a week spark.
But that doesn't sound like what you are having because if it was you would not be able to charge it up and restart
Load testing the battery after charging to full on my 2 amp charger the battery goes from 13.8/14.2 to under 3 volt in under a minute and under normal working conditions the charging system should be enough to run the ignition but with the headlight on the the battery gets so little the ignition gets nothing and misses bad and I shut it down put a light charge to get home 5000 yards and then another light charge to get it into the shed I really hate pushing it. A proper sized battery gets here late today early tomorrow for the next 3 to 5 years. And I was told the YUASA 51814 has been discontinued by local supplier. Looking at the rear fender to make more room for a larger battery will mean modiiying the battery box floor and the rear fender to gain the 4.5 inch required for the YB-18L-A's depth and a more readilly available battery and better suited to also using my sidecar later.
-
Yuasa may not make the 51814 but others do including the OEM fitment Varta. There is no real problem finding a battery - many here use one of the generic AGM batteries as listed in the top section of this board. They are a perfect fit and excellent value.
-
Replacing the battery is good but make sure you check the charging voltage after you install it.
Just because the charge light goes out doesn't always mean your charging the battery
You should have at least 13.5 volts after a minute or so at 3000rpm
if you install an AGM you will want to turn it up to 14.2.
If your able to charge the existing battery up for just a short time and restart and drive the bike your battery is good. (well it is working but may have low capacity from being deep cycled)
The new AGM batteries that fit the stock battery tray have more than enough capacity unless you do a lot of idling and stop and go traffic.