Ignition Cut Out after changing Coil

[jonathanrowley]

My 1981 R65 was treated to a new Bosch Coil today, the original one was working OK, but I thought it deserved an upgrade s it was 35 years old and looked pretty ropey. I had also experienced some misfire,  so I got a BOSCH 0 221 500 203 - suitable for 1981 R65.

I fitted it and started the Bike - OK for a few seconds then it died.
The ICU felt very warm, so I refitted the Tank and tried again - no luck.

So I decided to refit the original Coil, then Tank - Bingo all fine again.

I took it out for a road Test and it died, several times, restarted, but only just made it back home!

I'm wondering if the fitment of a new Coil could have blown the original ICU or overheated it?

On a related note, I haven't got any heat grease behind the ICU and have been reading that this causes similar issues.

Should I refit the new Coil?
Buy a new ICU then refit the new Coil?
Grease the original ICU?

[georgesgiralt]

Hello Bluebossa !
Your picture, I hope, shows the old coil and a different from OEM ICU. If it is the current set-up I wonder what's wrong ?
The new coil has a very low primary resistance able to draw 24 amps from the ICU. So if your ICU is not made to deal with this coil it is normal for it to overheat and cut off operation when too much is too much.
I own an 1982 R65 and the original OEM ICU. It is able to run the new BOSCH coil and feed it only a little above 8 Amps. So you may have luck with an OEM ICU.
Hope this helps.
P.S. these ICU form factor was used by a great lot of European car and bike manufacturers at the time. But the innards are different from one need to the other. Peugeot, BMW, Fiat and a lot of others used them. I had an ICU from a Peugeot car die on me and the BMW bike one was not able to run the car...

[jonathanrowley]

Hi George, Picture is indeed original Coil and ICU.

You can see how ropey, rusty it is, hence the change.
Here's the new one... now off the Bike.

Do you think I need a new ICU to drive it?
My mind says the new coil fried it...?

[georgesgiralt]

Does not look like mine but may draw too much current from your actual ICU.
Try to put some thermal paste between the electronic box and the aluminum radiator. Bear in mind that a lot of modern ICU are permanently riveted to the heat sink and can't be taken apart without killing the ICU... So BEWARE !

[Bob_Roller]

I suggest checking the resistance of the primary circuit of the new ignition coil and see what you have .
If it isn't 1.5 ohms, or close to it, it may be an issue .

[jonathanrowley]

OK thanks, I'll try and take it off and see if it splits, need to find some heat synch grease.

I've just found a new ICU one on EBay UK.

http://www.ebay.co.uk/itm/151923265077?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX

Hopefully this should help... if it is blown.

I think as everything electrical was original and have gone through 35 English Winters they have done pretty well, so time for a bit of selective improvement.

[Bob_Roller]

I found some information on that new coil you have, it looks to be a .5-.6 ohm primary circuit resistance .
The original OEM coil you have is a 1.5 ohm coil .

http://www.largiader.com/articles/ignition/

This coil is mentioned in the '81 and later paragraph .

[jonathanrowley]

Hi Bob - thanks, yes I was just reading Snowbums site.

A minefield of numbers and upgrades!
I'm still a bit lost -

Do you think my suggestion then that the new coil blew / overheated the ICU is correct and that even that I've reverted back to the original Coil the ICU needs to be replaced as it's shot?

Also do you believe the new ICU I've ordered will work with the New Coil Bosch 221 500 203?

Thanks for the help

[jonathanrowley]

New Bosch Coil 203 measure 1.4/5 Ohms Resistance Across the Terminals

[Bob_Roller]

Coil most likely is not your problem .

[Barry]

On the face of it the coil looks to be the correct spec and the ICU should have coped with that.  Just for comparison what did the old coil measure ?   The reason I ask is it's not easy to measure very low ohms values accurately. In fact it's quite common for digital multimeters to not zero out when the probes are shorted so it's possible the coil has a lower resitance than indicated. If both coils give similar measurements that should give you confidence that the new coil is the correct part.

[jonathanrowley]

Old Coil is on Bike, but I will measure when I next fiddle. I think it's the right one.

I still think the ICU has gone Bang - maybe the New Fresh Coil just asked to much of it and heat damaged it.

Makes the Bike not rideable or reliable for the moment though, so back to the car I think. I'll get the new ICU and replace. Will report back.

Thanks for the help..

[georgesgiralt]

IMHO, your ICU and alternator regulator are not OEM BMW so were changed at some point during the bike's life.
If the ICU was original it should have married very well with the Bosch coil you bought which has 1.5 Ohm primary resistance (which is the original value the Crak-O-Matic has)

[jonathanrowley]

Hey George, well spotted the Regulator I recently upgraded for a Euromotoelectrics variable aftermarket one.

Reason being they help charging I believe as they allow an extra few volts across at low RPM. I hadn't thought of this until you raised it.

Anyway, just to eliminate it from the enquiry, I just switched back to the OEM one and the Bike now refuses to start completely.

Regarding the ICU, I really don't know, it was in the box of bits and I haven't changed it - but you may be right and it's not OEM. Unknown to me.

Any further ideas/tests?

Because I'm in the UAE, parts like this are hard to come by though if someone can recommend a Car compatible one known to work on the R65 I'm sure I could find that here in the desert.

I've ordered the one in the UK from eBay but that might take a few weeks to reach me...

Further update - decided to put the new coil and regulator back on so that I could:

1. Get the number off the ICU - its a Bosch 277 100 103 : See pic, not listed on any site I can find as yet, so definitely a replacement?
2. Measure the old Coil - 3.2 Ohms (if I'm doing it right?) - seems high compared to new one at 1.5 ohms
3. See if it would fire up - briefly, smelt a hot ICU again.

[georgesgiralt]

Hello Jonathan,
Looking at my archived notes, I can tell that the original OEM ICU (for bikes with the kick starter) is BOSCH 0 227 100 113.  It cuts a little bit later than the stock one in order to let you jump on the kick starter to start the bike. I wonder if yours is the correct one with a different heath sink ?

Your original coil looks strange to me. The coil itself is OK but the fixture  is quite strange to me.
Alas I can't take a picture of my ld one as I destroyed it to re-use the support for a Fiat Tipo ignition coil (0.8 Ohm primary, dual output) I got for a song at a car wreck place.
As per the primary resistance at 3.2 Ohm, I would not bother too much : Corrosion may add up a little at the screwed tongs, and measuring very low resistance is a bit tricky because the resistance of the measuring wire add a significant error to the measure and you ohmmeter needs a good battery and one giving the necessary current to the measured resistance. So a difficult job for a very cheap Chinese meter... 50 % error is not uncommon.
As per the ICU, I bet you fried the one on the bike. At this point, IMHO you have a couple of way to go :
1) buy the latest ICU from BMW (around 150 Euro ) which should fire properly all coils past and present
2) find a correct second hand one. Buy from a reputable source as it is difficult to see from outside if the unit is toast or not. (http://motorworks.co.uk/vlive/Home/index.php comes to mind, but there are a lot of others)
3) try to go at car wreck places with your ICU in the pocket and try to find one. This is the last resort option IMHO because where you live, they seldom saw cars using them...
Hope this helps.