So I recently got a 77 LeMans 850 back on the road after a 22-year sleep. The bike had a Dyna III installed, so I left it in, and it sparked both cylinders (although the spark on one side may have appeared a little weaker than the other). I checked and cleaned all the conectors and went thru the distributor, and timed it dynamically.
The coils that came on the bike were some generic-looking ones and they were horribly corroded. They measured about 4 ohms. I swapped them for some OEM Guzzi coils I had laying around that Chris Collins sent me that measured 3.4 ohms.
The bike starts right up, usually on the bump, but after a long ride wants to die at idle and then doesn't want to restart, maybe one cyl worse than the other. Let it sit five minutes, not even enough for the motor to cool, and it starts right up on the bump and settles into a perfect idle again.
The motor's fresh, and compression is 175-180 on both cylinders. Jetting is stock and the plugs look ok, although after a 100-mile ride Saturday they had a little dark spot on one side, and one was a little darker than the other.
No smoke, and the motor sounds fine.
I gather the "normal" Dyna failure mode is a cylinder dropping out. Does this sound like a coil failure? What's a good coil to use other than the Dyna black coils (which are now the recommended coils per Dyna over the greenies, I think)?
TIA
The coils that came on the bike were some generic-looking ones and they were horribly corroded. They measured about 4 ohms. I swapped them for some OEM Guzzi coils I had laying around that Chris Collins sent me that measured 3.4 ohms.
The bike starts right up, usually on the bump, but after a long ride wants to die at idle and then doesn't want to restart, maybe one cyl worse than the other. Let it sit five minutes, not even enough for the motor to cool, and it starts right up on the bump and settles into a perfect idle again.
The motor's fresh, and compression is 175-180 on both cylinders. Jetting is stock and the plugs look ok, although after a 100-mile ride Saturday they had a little dark spot on one side, and one was a little darker than the other.
No smoke, and the motor sounds fine.
I gather the "normal" Dyna failure mode is a cylinder dropping out. Does this sound like a coil failure? What's a good coil to use other than the Dyna black coils (which are now the recommended coils per Dyna over the greenies, I think)?
TIA