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Motorcycle Repair/Ignition coil resistance


I need to know what range of primary coil resistance is allowable on the points and condenser ignition system on my 1974 CB750. I'm relocating the coil mount and can't use the stock coils. The coils that I have on hand are 1.5 and 6 ohms.

Marty,  Common resistance readings on OEM points/condenser ignition coils are about 4 to 5 ohms.

Dyna offers coils with 3 ohms, which they claim will work for points/condenser ignitions, as well.

You can see here that they originally went with 5 ohm coils for early fours.

Ebay number 111189084772

1.5 coils are for CDI or electronic/transistor ignitions. 6 ohm coil may be out of usable range.

Bill Silver

Motorcycle Repair

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Bill Silver


Need help with vintage Hondas from the 1960s? I am an expert with 250-305cc bikes in particular and most all of the other pre-91 models, in general. I do NOT claim to have a great deal of experience on Gold Wings, Cruisers, ATC/ATVs and dirt bikes.


I have owned/ridden/maintained Honda motorcycles for 35 years. I have written five books on Honda repairs and collecting. I was a service manager for two Honda shops back in the 1980s.

VJMC (Vintage Japanese Motorcycle Club) of North America

VJMC newsletter, as editor for two years and as contributing editor currently.

3 years auto shop in high school, teacher's aide in Automotive Technology in Jr. College, Diesel mechanic course in college, self-taught mechanic and automotive writer.

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