Somethings amiss with my 1984 R65

[raymr]

Any chance there's water in the gas tank? Are you switching to reserve and picking up water that's in the bottom of the tank?

Can you tell if the problem is affecting both or just one side of the engine?

[Graeme]

I had the same problems about six months ago & it was the ignition control unit ('84 LS) replaced by my mechanic who had to collect the Bike & me after it let me down completely.

Backfiring, appearing to run on only one cylinder.

It cost me a heap of money mainly for diagnostics. (The wiring was poorly maintained by the previous owner).

[Hunsta]

OK. Been a while since I started this line of questioning, and the last 18 months have blurred past. I got very distracted and the R65 with new ICU in box went under a blanket til yesterday.
Now having said that, I attached new ICU with a very light smear of heat transfer paste(no I didnt use Dielectric grease) and when I connected it all up and turned the ignition key, it did some strange things. Firstly the taco needle rose to the end of its travel, and it would not even attempt to turn over. I connected the old one back up and everything seemed to return to normal.
Now the ICU that was in the bike was a Telefunken with a part number on it. 1214-1244 477. I bought a replacement part from Moto-Bins in the UK and their parts was for  1981 on non kickstarter Herth + Buss with a part number of 19010 001 and this is on the picture in the Moto-Bins site, but the BMW part number for it on the site as well was 12 14 1 244 482. Clear as mud right?
 So technically why did it not seem to work? I didnt actually start the bike as I didnt have the tank on. However it did turn over with the old one on it and didnt do the freaky tacho needle thing, like the new one did.
So any thoughts? And to confuse things even more could my original problem have been the Ignition trigger pick up and wiring (guess you might have to go back to original post) as explained in the ad on the site.
"IGNITION TRIGGER PICK UP AND WIRING ALL AIRHEAD TWINS 1981-1995.  THIS IS THE PART INSIDE THE TRIGGER UNIT HOUSING THAT IS USUALLY THE FAULTY PART.  WHEN THE TRIGGER UNIT STOPS WORKING YOUR JOURNEY ENDS.  THIS ITEM HAS JUST BECOME AVAILABLE AGAIN. "
Craig

[georgesgiralt]

Hello !
The tacho is fed from the coil. Not directly from the ICU.
So IMHO this is a wiring issue (some wires are worn out or anything else).
I would try something to clear the issue :
Unplug the tacho at it's plug (easy)
Remove the two spark plugs and plug them back into their caps and secure the metal base of the plugs on the cylinder heads.
Turn the ignition on and try to start the engine.
Do you have sparks at the plugs ?
If yes, the ignition is working, if not you've to investigate a bit further.
Last but not least what kind of coil do you have ?
Keep us posted !

[lrac]

Hello,
It looks like you have recieved lots of good suggestions.
The new icu may be compounding your trouble, it may not be the correct part even.
You said that the coil was replaced earlier, was this because of this same condition.
I have had coils cause this trouble, when they get hot winding may go open and then
close again when cool.    
        
               Carl

[Hunsta]

Ok. With the ICU and the strange taco movement,  I'll repeat what I said before. With the new ICU the taco needle moved all the way round and I could not get the motor to turn over. I put the old ICU back in it and every thing was normal. This leads me to the conclusion that the new ICU may be for and airhead, but the connection point may be wired differently.
The coil in it is a Dyna coil (brown). And just to recap the original problem was the bike when hot gave a loud backfire and stopped only to start and run perfect again when cold. And it was suggested to check the ICU's contact with the heat sink. When I did found it was loose and no heat sink paste. And this was suggested that this was the trouble as the ICU was heating up then failing.

[Bob_Roller]

I would start checking your electrical connections for security and condition (corrosion) .

Check the 'pins' in the connectors for security, so they are not being pushed out when the connector halves are mated up .

I had a similar problem with my '81 R65 about 16 years ago, I never identified the faulty connection, but after I pulled all of the connections apart and put them back together again, hasn't happened since 1997 .

Ignition switch and kill switch are prone to cause problems as well .

A frustrating situation with intermittent electrical problems, just don't start 'throwing' parts at this without troubleshooting, it can get costly and still not solve the problem .

[Hunsta]

Ok let see if we can simplify things here. Old ICU is a Telefunken. Part no. 1214-1244 477.
New ICU is a Herth-Buss. Part no.19010 001.
My bike is a 1984 R65 non kickstarter.
Can anyone tell me if this is the correct ICU for my bike?
Cheers
Craig

[Bob_Roller]

You will have to find some reference for applicability of the parts from the manufacturer .

I do know that the ICU's from early '80's VW's will work, this ICU was common in European cars in the early '80's .

Sorry can't be more help .

I just checked the Herth Buss site and the part number doesn't come up, may be a discontinued part or the part number may have been changed .

[Hunsta]

The Herth-Buss one is the one they sold me and seem to still be selling from Moto-Bins UK

[tvrla]

I seem to recall that the tach signal does come from the ICU. And it makes sense if swapping ICUs gets rid of the problem (or causes it).

Basic troubleshooting.

If nothing else, the new ICU may be faulty.

Did the old ICU malfunction once the base was cleaned up, new paste applied, and fastened properly?

[Hunsta]

If nothing else, the new ICU may be faulty.

Did the old ICU malfunction once the base was cleaned up, new paste applied, and fastened properly?

I havent fired the bike up yet, but when I put the old ICU back on it didnt do the strange tacho thing and did turn the bike over

[tvrla]

Troubleshooting 101 says the problem most often resides with the last change made. That's the first thing to check out. And the fact that the new symptoms disappear swapping back to the original says there's something wrong with the new one.

[Speyman]

When I got my 1981 R65 a few years back, I had the similar symptoms. Had to walk home several times. Someone on this forum suggested I check the kill switch. I took it apart, cleaned the electrical connections, lubed with dielectric grease. Problem solved.

It is so easy to do, you might as well try. The switch needs periodic maintence anyway.

[Barry]

If you ever get stuck and think it's a faulty ignition switch or kill switch then by-passing it is simple enough. All you need is a short length of wire with a spade connector on one end and a crocodile clip on the other. No tools needed. In fact hot wiring a twin coil model is ridiculously easy.

Connect the wire from the battery positive to terminal 1 on the rear coil. You can fit that without even lifting the tank once you are familiar with the coil connections. Single twin out put coils may be harder to get at but in principle it's the same.

It's a good idea not to leave this connection on for too long when the engine is stopped as the coil will eventually overheat.