what to do if your coils are bad?

[mitchberry]

hello, i have a 78 cb750, and i'm affraid that my coils may be bad... I know that on my 69 suzuki T500, when my coils went bad, i just went to autozone and bought some coils for an 85 camaro z28, swapped them bad boys out and it ran considerably better than it did with the stock coils..

 well... i don't know if i can do that with these ones since there are two coil wires sticking out of each coil..

what do you replace these with if they are bad???  i assume just about any coil out of just about any 4 cyl bike, but, i'd like to know for sure..

[vern401]

Well you have a few options. You can get new ones. or do a GM mod on it.
The GM mod I have not tried since the resistance is much lower on the coils than the factory stock. This would create more draw on your charging system. Here are some links you may find helpful.

http://www.cb750c.com/modules.php?name=Forums&file=viewtopic&t=125

https://www.partsnmore.com/cat_index.php?model=cb750_sohc&category=electrical

Or ask in the forum for some used coils that someone may have. I advise the new coils since we do not yet know what the conversion will do to the points on our bikes.

[Re-run]

Hey Vern! right about the coils. I can expand a little.
Lower ohm coils can be used. As Vern said, there will be more draw so you will want to make sure all your grounds and connections are good.
The other issue is that the points and condensers will get chewed up faster. What happens is the greater draw causes more arcing on the points which then requires more dressing to keeps pits and spikes at a minimum and thus wears out the contact blocks faster.
Another common coil were the 750/900 dohc coils but again, lower ohms.

If you run an electronic ign, ohms are also important. Your system may not support anything under 5ohm. I know the dyna models support 3 ohm and such but I am not sure about the others.

Another option is to switch some of your lights to led lights to cut back on overall current draw on the charging system.