Ignition Trigger Can Testing, not +12V?

[Barry]

There are some Harley coils which would work and I should think easy to find in the US.

[mrclubike]

There are some Harley coils which would work and I should think easy to find in the US.

Funny you say that because I thought the same
I had heard that older Harley's used this type of coil
In 2016 I broke down with a failed Dyna coil north of Indy
We had just passed a Harley dealer about 10 miles back and i thought they would have one  for sure because of all the Harley's we see on the road 
So I  called  them to make sure they have one
They acted like I was crazy because they didn't carry any older Harley parts
I was able to find a used coil at a little ATV repair shop and it got me home 
One could also get 2 coils from an old Ford V8 and wire them in series like the points bikes had just to get you home
because it wont be pretty   

[flon3y]

Thank you all for the help.

I ended up replacing the coil with a blue Dyna (and bracket), put new plugs and wires (both were incorrect spec installed by the previous owner), adjusted the valves, adjusted the ignition timing , and adjusted the idle/mixture. The difference after all this is night and day, it's running great now!

I don't think the previous owner knew what he was doing with this bike which is funny given he provided me with Clymers manual that explained all of this...

[mrclubike]

You  need  the latest version ICU to use the blue coil
The blue coil  has a primary Resistance of .7 ohms  and can over heat the older ICU's
That is why I recommended the brown 1.5 ohm coil

[flon3y]

Hi Mrclubike, is my Clymers incorrect in specifying the 0.7 ohm coil for an '81 R65LS then? When did the 'Later' ICU start being used?

[Barry]

is my Clymers incorrect in specifying the 0.7 ohm coil for an '81 R65LS then? When did the 'Later' ICU start being used?

Yes it is.

I don't believe a 0.7 ohm coil was ever used on an R65LS. You should have a 1.5 ohm coil as the very low resistance coils weren't introduced until 10 years after your bike was built. I'd either change the coil or carry a spare ECU of the latest type.

[mrclubike]

Hi Mrclubike, is my Clymers incorrect in specifying the 0.7 ohm coil for an '81 R65LS then? When did the 'Later' ICU start being used?

Yep
I told you to get a Brown coil  
Like Barry said get a later ICU if you do not know if it has not been changed
The later ones have a larger heat sink and wider bolt mounting pattern and require an adapter or a different bracket if you existing bracket is bolted on 

Snowbum's website has very reliable information
 Clymers can have errors 

http://bmwmotorcycletech.info/ignition.htm

I have used 5 different coils and i could not tell any difference in performance
Only difference was the temperature of the ICU
Lower resistance = more heat

[mrclubike]

Your ICU bracket needs to look like this in order to use the new style factory mounting bracket for the later ICU


Here is the OEM bracket for the Later  heavy duty ICU
http://www.euromotoelectrics.com/Bracket-Ignition-Module-BMW-R-61-31-1-244-832-p/ignmod-bracket832.htm

[mrclubike]

Some of the R65s have a welded on ICU bracket
Like mine
Cant use the above bracket with this

[georgesgiralt]

On the other hand, when my Crack'O Matic OEM coil died, I bought the current BMW coil (black with red spigots) and installed it.
Then I read my ICU will fail. So I bought a new OEM one.
Two years after and many miles more, the original ICU is still going strong.
But YMMV ...

[Barry]

If the 0.7 ohm coil works with older ECU's then that's fine but I would also be thinking about the fact that the ignition system could in theory be consuming double the power from the alternator and that the cables in the wiring harness are passing double the current they were designed for.  I expect the later type of ECU manages dwell better to mediate the average current and heating effect. It would be interesting to measure the difference between them in this respect.

[Bob_Roller]

I have the original  ICU on my '81 R65, the original black and gray coil quit in 1994, I replaced it with the later version OEM coil, the red and black, it failed in 2006 .
I've had a DYNA brown coil since then, at least so far, no issues with the ICU .
I ride in one of the hottest areas in the US .

[mrclubike]

On top of ICU heating the coil can be over heating also