I really appreciate the R&D Lou D put into these conversions. I just finished on a 1980 CB650, using a pair of 'Blue' performance 4-pin modules I found on ebay for $26 total and $2 in resistors & diodes from Digikey for a bias supply. Stock ignition coils, measuring at 2.4 ohms each. First time starting, nothing happened! Found I had conveniently left off re-connecting the coil wires after measuring them. Tried cranking with plugs 3 & 4 lying out on top of the head and got spark. Tried starting again, carbs 3 & 4 started dumping fuel out the overflows. Old bike issues...
Advanced the ignition timing and finally it's running! But smoking like crazy, must be all that fuel
Put bike back together, reset timing to where I had marked it. Proceeded to ride around the yard. Now normally if I had tried shifting to 2nd gear around the place, I'd be stalling the bike and going too fast to avoid hitting the garbage cans without pulling the clutch. Today I putted around in 2nd like I was still in 1st and able to roll-on throttle without hesitation. Very nice!
Grabbed the helmet and hit the road. Now the shifter has always been a bit finicky. Any sort of weirdness and it downshifts. That happened about 5 or 7 times. I'm guessing that the ignition is suffering from too much crosstalk. I had not changed the pickup gap, but I did note that a 0.6mm feeler gauge would not fit, it might be the pickups are too close and the voltage levels are just high enough to get the crosstalk acting up. Riding at low RPM's was very smooth and no sudden hiccups into 4th
Parts and sketch based off of Lou D's work:
Sorting out which wire on pickups is the positive:
Mapped out the stock connectors that I had chopped off the old modules:
Map of connectors is viewed from module's point of view. Both connectors have the same pinout, but on one connector the pickup wires are blue while on the other they are yellow. I think this pinout might be the same for all years of the CB650. So if you don't have a 'scope, cross your fingers & try it like I had it
Roughing out a mounting bracket:
Instead of the silicone grease, I decided to try some of my magic CPU thermal paste. And riveted the 4-pin modules into place because I am that confident about this whole magic business:
Built the bias supply as a discrete module:
No tape or heatshrink, just lots of hotglue:
The more astutely keen-eyed will note I am also doing something else to the bike:
I took apart the advance, because it squeaked when I turned it by hand. Cleaned, then coated all moving surfaces with silicone damping compound in order to get a less jittery timing
So some more fine-tuning for tomorrow. But so far I am very impressed! Bike went from having a nervous attitude pushing into corners, to getting into and then out of slides halfway through fast corners. Not sure if the top speed improved any, the speedo only goes up to 85. But it sure does seem to get there a whole lot quicker. And smooth!