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I got my '83 V45 Magna inspected and tagged today! If only I could ride the hell out of it... The bike fires up and runs for a short while just fine. Maybe 10 mins. Then it starts to get sluggish and progressively worse over about 5 minutes until it stalls. When I pull the plugs the front 2 are wet and dirty but the rear ones look fine. I put one of the front plugs into the spark wire boot, grounded it and hit the starter- no spark except for a small one as soon as I let off of the starter. I put the same plug into the rear wire boot, hit the starter, and got a consistent spark. I've diagnosed this as a bad ignition coil since those two plugs run off of the same coil.

My question is- are old, used, OEM ignition coils really worth spending $50 on to replace these? My bike only has 15k miles on it so I'm guessing the coils are failing due to age. I've read about people with CB750s and 900s swapping their coils for ones off of Chevys-

Does anyone know if this is possible or advisable on a Magna??
 

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Do the front and read plugs fire at the same time? If not, you may want to check the igniter and power supply to the coils first. Each coil should have battery power at one terminal, and the other terminal goes to the igniter. If the connections are bad, or the igniter, you'd get the same results.

Using a voltmeter set to ohms, compare the coils with the wires disconnected, both across the low side terminals, and from the plug wire to either of the low side terminals. Both coils should be nearly the same.

If they are, read the voltage at the igniter side of each coil to ground, with the engine running, on the AC setting. Again, they should read nearly the same.

If both tests pass, the coil is bad. If not, first test is for a bad coil, second, the igniter.
 
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