Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: Johnny4428 on February 01, 2021, 11:13:42 AM
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Anybody have experience with this type of ignition. The question I have is it compatible with standard coils? The bike came with it fitted but apart from a garage run I never had the bike out on the road.
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I think they may have made them for original coils in one spec, and separate for their coil set with different resistance of their coils.
Is there any identification on them to help?
As I understand it, the original Honda coils, at 5 ohm resistance, are used specifically for points ignition to suit the dwell characteristics of the switching. Points systems have the dwell (the time which the points are closed in order to "charge" the coil) time changing with crankshaft speed, which the coils are arranged to accommodate.
Where as electronic systems can run with predetermined dwell time held static throughout the full rev range, and make use of different coil resistance.
One system will run the other type, but with unwanted side effects, so will function. But as you have asked, you'll need to identify what you have installed to fully understand if you need to do anything.
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Sorry I meant to attach photo to previous post.
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All the anecdotal and specific discussion I can see, indicates that the Dyna S is to run standard coils at 5 ohms, so should all be ok for you.
Worth cleaning the connectors well and use something like silicone grease to help exclude water and keep reliable continuity during installation.
Also check the voltage regulator output of the bike once it's up and running as they seem susceptible to too high voltage when in service. The risk area is above 14.5v supply, so you should be well below that ordinarily, but worth considering.
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Thanks very much, most helpful. I am just in the process of cleaning up engine internals at the moment.
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It is reported on the US site that if you fit the 3 ohm coils that dyna want you to fit the current draw goes up enough to cause charging problems in slower riding especially on the smaller fours that dont have much spare generator output
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Just wondered Bryan, I was in the process of repairing old coils. So does that mean it’s probably better to stick with the 5ohm coils?
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I have a full Dyna system on my 500 and have no issues with low battery. Longest run was about 120 miles last year.
Hope the info helps