The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: plc on May 11, 2009, 10:50:12 PM
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Hi Guys,
On the way to work, Thankfully almost there, my bike started misfiring and coughing. It would idle, but the tacho was reading zero rpm (not the only time it does this but rarely when warm). I got up the hill at work, but now the bike will start and idle roughly but no matter how much throttle the motor speed doesn't get above a rough idle.
I have checked and replaced the fuel filter, all good there, bike now has plenty of fuel, so that seems OK. New spark plugs fitted also no difference. Also there isn't throttle response applying throttle at individual carbs.
What do you think guys? I checked dual coil, didn't seem physically damaged and looks newish too. A guy here said he has seen points bikes do this when the condenser is stuffed. Does that mean the trigger unit is stuffed? Yesterday I did about 100 km of freeway riding at around 110 km/h, so that may have accelerated (pardon the pun) some part failing.
I would appreciate the forum's collective wisdom.
Best to all,
Paul
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This was exactly what the "Junkyard Dawg" was doing yesterday. It would start, and sorta idle on one cylinder and wouldn't accept any throttle unless I choked it. It turned out the idle jet was clogged...
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I assume the tacho is a clue to an electrical problem ..... unless it is cable driven.
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I think all R65s used an electronic tach...
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The usual suspects: drop the float bowls and verify cleanliness and fuel supply. Maybe remove the main and check for clogging. Then you can pull the tank and check electrical connections are clean and tight. Can you verify paste on the back of the ICU? Pull the front engine cover [remove battery connection first] Bean can on tight? Covered in oil, rust?
Connections clean and tight? The Tach is trying to tell you something I suspect.
rich
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mignt be worth checking the spade connectors to the coils (this would tie in with the tacho) and if your pulling the tank off i would drop the fuel valve and check the inlet pipes........did you try it on reserve??
Lou
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The ICU sends independent electrical signals to the coil and the tachometer, they come off of different pins on the ICU.
You may have a hall effect sensor failing in the 'bean can', or the ICU may have issues.
I would check the wiring as mentioned, and if you have the ICU where the heat sink is removable, and renew the heat sink paste there as previously mentioned.
Until you have a complete failure, I don't know of any test method that can tell for sure which component it is, as it does still work, just not like it's supposed to.
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Did anyone mention checking the carb diaphragms? I had that condition in my 81 R65. Even a pinhole leak can cause rough idling and no acceleration.
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It might be a red herring, but the tachometer thing seems to indicate an electrical gremlin that needs to be tackled.
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Hi Guys,
Thanks for all the suggestions. I am going to check the ICU first, because the bike runs on both cylinders, will run on either cylinder with the plug out and grounded, and neither carb responds to throttle. I want to see if it has a weak spark, obviously it has a spark as it runs. So if it is diaphragms it would be both, which I am sure is possible. I will also check to see if the bean can is mounted tightly and has not moved, last I checked it was fine but you never know.
I will keep you posted.
Paul
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Hi Guys,
I checked the flow to the float bowls, the float operation, the idle jet and the main jets. All seems OK.
I checked the coil resistances. Primary winding is 0.9-1 Ohm. The secondary winding is 12.82 kOhm. I am seeing mixed messages on sites and from my Clymer book. The Clymer book says that the primary should be 1.15-1.32 and the secondary should be 7.5-9.15 k? Yet some posts say 11 kohm is fine?
I have a spark at the plugs but it isn't great, looks a smallish spark. Do you guys think the coil is in the death throes?
All the best,
Paul
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What color is the spark? Yellowish/orange indicates a weak spark and blue usually indicates a healthy spark...
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It was bluish colour, I suppose I expected a bigger spark, that was brighter.
Paul
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My 1983 R65 had similar issues. Check your coil.
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DgM, I have checked the coils but I am confused by the resistance reading which I listed in an earlier post. My secondary winding is 12.86 kOhms, which most sites and books say is too high but I have seen contrary comments on the web that say this is normal for the latest coils. My primary winding is 1 ohm, which is in no-mans land. I suppose I am curious if this indicates the coil is breaking down.
I have enquired with Rick from Motorrad Electrik about those figures before I order a Dyna coil from him.
I would appreciate any further input.
All the best,
Paul
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If you still have the original coil, inspect it very closely for hairline cracks. Check the ends of the coil. A strong flashlight and a magnifying glass may be helpful.
If you find any cracks at all, Rick Jones is the go-to guy for a Dyna coil. Have them on both my R65s.
Monte
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Your primary resistance is a bit low, my last OEM coil had .7 ohms for the primary, bike ran alright, but developed a hard starting issue at around 55 F.
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Hi Guys,
I tested the ICU by flicking the kill switch on and off, there is a spark at both plugs. Then I took off the bean can and rotated it, a spark appears but there is one at each plug per turn. Then I put a multimeter between the green trigger wire and the earth and then the voltage goes from low to 3.7 volts. That seems low to me, I thought it was meant to go to at least 9 volts.
The spark also seems inconsistent at times when I spin the bean can unit, is speed important or should it always trigger a spark?
Paul
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It should trigger a spark on each full rotation. Both plugs will spark together even though one side will be going on the exhaust stroke - that is why it is called a wasted spark system - by design.
I don't recall if the voltage should go up higher or not - can't recall last time I measured the output, but it is important that the output pulse go low and high on each rotation.
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The electrical pulse from the hall sensor, is just an input to the ICU, the ICU then takes the signal, and amplifies it to what ever is required to 'fire' the coil.
The fact that the voltage goes from low or zero, to a higher voltage means it's working.
Problem is, there is a possibility that vibration and heat may be the culprit causing an intermittent operation.
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Should the drive part of the bean can that connects to the camshaft have movement? Mine has slight movement for and aft and it can me made to wobble side to side.
Paul
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OK Guys,
I tested voltage as the Clymer manual describes. Voltage at coils OK. Voltage at ICU not there, pulled out wire 5 and then tested current between pin 4 and the wire, reading was 1.2 mA, which according to Clymer manual means faulty trigger unit.
Interestingly my ICU did not have a wire to pin 7, yet I have read that is the tacho pick-up, so now I am puzzled how the tacho gets its signal, because it works, although I suspected it was reading slow.
Paul
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Should the drive part of the bean can that connects to the camshaft have movement? Mine has slight movement for and aft and it can me made to wobble side to side.
Paul
Yes. Note also the light spring that is a part of the bean can drive coupling. A little designed-in movement permits the drive lug to self-center on the cam shaft end. No worries. Monte
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Pin number 8 should be the tachometer signal out of the ICU.
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Hi All,
Well my bike is running again now that i have fitted a new Ignition Trigger unit (Bean Can), even buying from Motobins it was pricey but I bought other things as well and including shipping it was cheaper than buying a new Bean Can in Australia.
I will now service the old one so I have a spare, hopefully the new one will last 25 years like the old one.
I just thought I would let everyone know it was the bean can so if you have a bike that won't rev or idle smoothly it may be a bean can like mine was. of course as I discovered it could be other things too.
Best wishes to all,
Paul