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Discussion Starter #1
82 Honda Magna V45 cb750.
Many problems with this bike since I got it couple years ago. Anyway, got it running ok (aside from carbs need a cleaning) then it kinda bogged then died on me. Got it home,after a mile pushing uphill, and checked wires. Had to solder one of plug wires but checking plugs Im only getting spark from 1 of the 4. I moved that plug into the other wires and still nothing. Maybe its 1 on left 1 on right, Ill go check. Not sure if it makes any difference but the front plugs always burn out and the top/rear plugs are fine...
 

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ok front left and right are firing, but not top left and right... Found a fuse came broke on top of connecting cap, will replace and see...
 

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80's bikes were made at the point if electronics that the systems were hybrid between volt systems and ohms systems. some run with volts others with ohms, so you are on a great jouney through wires! of course you know that the plugs run with high voltage current supplied by coils and the little fuse thingys in the plug caps are noise/arc suppression semi conductors right?!!!
 

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Discussion Starter #5
Fuse thingys in plug caps?? I replaced the 2 fuses I found old broken, still same. Top/rear plugs not firing. Could be coil or rectifier??
 

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There are a pair of pulse generators that provide some sort of pulsed power from the stator to the coils. Think of it as the electronic version of Points ignition. Easy to test those. No longer available as I got the very last ones in America from Honda inventory.

There are a pair of spark makers close to the fuse box.No longer available, but some nifty aftermarket are available

As you also know, there are two coils.

See the theme here? you get to play detective and determine which of these three is preventing a pair of pistons from firing.

The first and easiest test to try is to trade the spark boxes and see if the non-working pistons then work and vice versa. There is also a resistance test on the pulse generator that requires a multimeter.
I will have to look up the Ohm's resistance of those,[I remember it as 56K] but for now, you could test each one at the connection plug just above the pulse generators and they should read about the same.

The coils should be tested after the others and can be tested by swapping them. I highly recommend the use of a timing light to test for spark and the cheaper one from harbor Freight will do just fine.
 
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