Some time in the late 1980s after killing at least two genuine Bosch/BMW coils, I replaced my coil on my 84 R65 with a Japanese twin lead coil off of some mid 1980s Kawasaki inline four. At the time I had no concept that the coil might need to match the rest of the system in some way!
In about 2000 the Hall effect pickup in the beancan (actually a Bosch car distributor minus vacuum advance, rotor button and cap) died (slowly, recovering when cold several times before finally quitting...) so I replaced it with the same part out of a 1982 JB Holden Camira (GM J car) which used the same Bosch distributor but rotating in the opposite direction, with vacuum advance and made locally in Australia.
In other words just about the only part that was the same was the bit I needed!
Then about 3 weeks ago a friends 1994 Ford Falcon refused to start. A weeks worth of evenings was spent diagnosing, extracting the distributor (from under the inlet manifold), getting it timed in right. Or wrong as the case may be. Maybe right this time? New cap, rotor and leads. ARgh. What is left?
Swap the coil into his wifes identical car. Problem moves with the coil... New coil $85, solved.
Needless to say it was the coil. It's just it's been more than 20 years since I've seen this failure, so it didn't occur to me!
Anyway the R65 is playing hard to run; backfiring and carrying on, and the carbs have been rebuilt. Leads are relatively new, copper with resistor caps. Obviously the valve clearances need to be checked...
But after that - well what's the normal replacement coil nowdays? Something off a modern car with dual spark coils? An old Japanese bike?
Graham in Melbourne