Signs of a Crack-o-matic coil failure?

[R65Singh]

Hello Fellow riders;
This site has been a great help and thanks to u all for your valuable inputs.
I am almost done restoring my bike and in the process of synchronizing the carbs after installing new timing chain BUT could not fix the erratic firing of one cylinder.  Double checked everything on the fuel side then decided to pull out the coil and sure enough there were two little hair line cracks on it.  It is Bosch...part #0221500200.  I also noticed that the timing light did not flash at the constant intervals on the failing side of coil.  May be that is a clue too for a failing coil?  
What u guys think?

[Bengt_Phorqs]

I think it's time to call Rick Jones at Motorrad Elektrik and purchase a Dyna Coil from him.  It's a very easy installation.  Just put one on Saturday with new spark plug leads, about $125 all in with shipping.

Monte "Mr. Bean Can" Miller has done some extensive writing about it on this forum.

[Bob_Roller]

Even if the bike wasn't having ignition problems, I would replace the coil, it's just a breakdown on the side of the road waiting to happen .

If you still have ignition leads with a metal cap on the spark plug end, it's way past time to replace them as well .

[drewboid]

Replace the coil!!!
There are many that will substitute - there is even an old Honda Goldwing coil with two sparkplug leads and the correct primary resistance.

[R65Singh]

Thanks guys...i guess i will have to look for one now.  Is the resistance 1.5 ohms or 3 ohms.  BTW Drewboid what is the number for Goldwing coil?...Always nice to know the alternatives.  Take care!!

[Bob_Roller]

The resistance for the coil primary circuit is 1.5 ohms .

[R65Singh]

Thanks Bob.  I just finished talking to a local BMW shop/mechanic and he is telling me that any coil with 3- 5 ohm primary resistance will do it.  He has Dyna coil in 3 ohms in stock and is asking $109.50 Canadian.  The only reason i am reluctant to buy it from the Motoelekt.com in states is the unknown Canadian duty/customs and the time it will take to get here.  What u folks think?

[Bob_Roller]

I don't know if the 3 ohm coil will make any difference, but the electronic ignition bikes use the 1.5 ohm .

The 3 ohm Dyna coil is for a bike with a contact breaker points type ignition system .

[Crossrodes]

Singh...

I live in Nanaimo and ordered a coil and other parts from Motorad.  I didn't have to pay duty or taxes (don't know why they didn't ding me for taxes.  That is the good news..the bad news is that it took 3 or 4 weeks for it to be delivered.

[montmil]

... I just finished talking to a local BMW shop/mechanic and he is telling me that any coil with 3- 5 ohm primary resistance will do it.... What u folks think?

i think, IMHO, that you should find another BMW mechanic/dealer who knows more about Airheads than selling improper parts to unsuspecting buyers.  [smiley=2cents.gif]

Monte

[R65Singh]

Singh...

I live in Nanaimo and ordered a coil and other parts from Motorad.  I didn't have to pay duty or taxes (don't know why they didn't ding me for taxes.  That is the good news..the bad news is that it took 3 or 4 weeks for it to be delivered.

Crosrodes....my friend...I am never that lucky with the customs and taxes and also in 3-4 weeks the weather may not be any good to ride....you know how the BC weather is.  It is beautiful  8-) right now.

I was also wondering if it is possible to swap the spark plug leads from left to right cylinders or right to left... to pin-point electrical problem from fuel problem?.  My left cylinder runs erratically and i am almost sure the coil is culprit and swapping the leads will confirm that.

[Bob_Roller]

You can swap the leads for trouble shooting purposes, both spark plugs fire at the same time, it's known as the 'wasted spark' ignition system .

[drewboid]

I got this from the omega ignition site:
http://www.stephenbottcher.net
Up to 1981 the point type ignition used two 1.2 ohm coils in series - total ohms 2.4.  Substitute coils are the Dyna green 3 ohm/black 5 ohm/grey 2.2 ohm or the honda #30500-422-003. Any 3 to 5 ohm coil should work.

After 1981 the hall sensor bean can and ignition module used either a single 0.6 ohm coil, a single 1.2 ohm coil, or two 0.6 ohm coils in series. Substitute a Dyna blue 0.7 ohm or brown 1.5 ohm. I don't see why a coil with a higher resistance would not work in a pinch although it may give a weaker spark due to less energy available.