Topic: 3 ohm vs. 5 ohm coils with dyna S

[IBleedHondaRed]

looking for advantages and disadvantages and experiences to the different resistance options for both a cb550f and a cb350f when used in conjunction with a Dyna S electronic ignition system. im reading conflicting things about recommendations for applications. im planning on doing updated electronic systems on both bikes and want to make sure im spending wisely

[dragracer]

I'm sure you'll need to use the 3 ohm coils. Typically the lower resistance coils are used in conjunction with aftermarket ignition systems  like msd or dyna boxes

[joe p]

I read somewhere that 3 ohm coils could be used on street bike but 5 ohm coils get to hot on street bike. I never ran 5 ohm coils on the street so I do not know if this is right.

[IBleedHondaRed]

the paperwork that came in dads box said to use his dyna s with 3 ohm coils. it also stated that the 5 ohm coils were for points setups. im seeing on here that many folks disagree. which sucks because we ordered dad a set of 3 ohm coils for his 73 cb500.

i want to know why people disagree

[joe p]

I ran 3 Ohm coils(green) with my Dyna S on my CB-750 for years without a problem.

[locomonza]

I ran 3 Ohm coils(green) with my Dyna S on my CB-750 for years without a problem.

Same here, no problem for years, 3 ohms Dyna s.

[Kemp]

I've talked to Dyna about the coil situation as the charging systems are so marginal on the CB350/400 and CB500/550 Fours. Dyna recommends the black 5 ohm coils for these bikes. Hondaman even offers a 2 ohm resister kit to use on the green 3 Ohm Dyna coils to reduce the current draw to that of the 5 ohm. The Pamco Ignition sounds like a better bet as its electronic system (ignition and coils) draws almost the same current as stock. The Dyna Ignition itself and Dyna coils themselves draw one heck of a lot more! Here (below) is a note I got from Pete at Pamco about using their system on the Honda CB400F

The stock points setup on the CB400F uses a 180 degree dwell angle (50% duty
cycle) with 5 Ohm coils, so the average current flow is 13/5 = 2.6 Amps X 50% duty cycle = 1.3 Amps. The Ultimate coil is 2.5 Ohms, but the dwell angle is 120 degrees for the PAMCO, or 33% duty cycle, so the average current is 12/2.5 = 4.8 Amps X 33% = 1.58 Amps. That's just 1.58-1.3 = 0.28 Amps more. Not a factor for the charging system. (The electronics in the PAMCO use less than 10ma, so not a factor)

[IBleedHondaRed]

DYNA finally messaged me back. they confirmed to use the 5 ohm coils on both the 350f and 500k