Topic: Simple way to test coils

[jabs83]

Is there a simple way to test the coils on a 73 cb750?

[Spanner 1]

Are they on the bike ?... if so you can test them with a meter on low ohms scale by touching the probes to black/white under the tank at the 3-way connector( coil wires unplugged ) and to blue and yellow wires disconnected from points.... must read very close to 5 ohms for stock coils.( Primary )
Fast test would be to open both points by sliding a piece of card between the point faces , turn on ign. and test for +12v at each point wire ( blue and yellow ).....
There are 2 windings in your coils, the above tests the Primary winding..... the secondary winding is the High Tension part and would be tested with a meter across both spark plug leads... not sure what the reading should be on the secondary.... maybe someone else can 'chip in' with info.......btw, coils very rarely go bad/fail, usually some other cause for ign. problems IMO.

[jabs83]

Thanks for the write up. So I guess the above method can be used to test the points as well or is there a better method for testing those?

[Spanner 1]

If you prove 12v on each point wire, as above, then re-connect blue and yellow to the points and open each point  by rotating the crankshaft...........voltage should go to zero ( points closed) to 12v ( points open ) as you turn the crank..... a very good time to read all about  'timing the ignition' in the shop manual.... downloadable here if you don't have one !