Author Topic: Dyna S Ignition system, street bike - What's the best coil? (Read 5668 times)

Eydugstr · « **on:** January 08, 2011, 04:17:09 PM »

Hello everyone - I am working on a '72 CB750, and pretty soon will be upgrading to a Dyna S electronic ignition. I know from what I've read that a 5 ohm is recommended for street use. Do you guys have any that you recommend? I do plan on riding this bike in summer heat, with the coils in the stock location under the tank. Any links or recommendations would be appreciated. Thanks!

swellguy · « **Reply #1 on:** January 08, 2011, 07:11:06 PM »

Dyna sells sets of green 3 ohm coils that seem to mate very well with their system:

Well mine are green, I guess they're black now.

Gordon · « **Reply #2 on:** January 08, 2011, 08:21:51 PM »

From my own experience, I can say I've been very happy with the dyna 5ohm coils. I've had them on my K1 for seven years along with the dyna-s. Never once had a problem with either the ignition or the coils. Many here also use the 3ohm version with no problems. They do draw more current than 5ohm, so that's something to look at if you have any other upgrades from stock that also draw more current, like an H4 headlight, or heated grips.

Spanner 1 · « **Reply #3 on:** January 08, 2011, 08:46:06 PM »

It seems from folks that use the Dyna S that 5ohm coils work fine..... you can use the 3 ohm coils if your O.K. with drawing 4 amps for each coil against 2.4 amps for the 5 ohm.... that extra 1.6 amps needs to flow thru' the Dyna control box increasing heat generation and presenting the battery with an increased load too, resulting in more sustained cycling of the alternator and the extra heat involved with more load.
No increase in spark output... I guess that's whats desired ?......... ( I'm a big fan of stock points, just for full disclosure

).

nokrome · « **Reply #4 on:** January 08, 2011, 08:58:36 PM »

i run the 3 ohm coils with my dyna s on my otherwise bone stock bike with no problems

Eydugstr · « **Reply #5 on:** January 09, 2011, 03:14:50 PM »

Quote from: Spanner 1 on January 08, 2011, 08:46:06 PM

It seems from folks that use the Dyna S that 5ohm coils work fine..... you can use the 3 ohm coils if your O.K. with drawing 4 amps for each coil against 2.4 amps for the 5 ohm.... that extra 1.6 amps needs to flow thru' the Dyna control box increasing heat generation and presenting the battery with an increased load too, resulting in more sustained cycling of the alternator and the extra heat involved with more load.
No increase in spark output... I guess that's whats desired ?......... ( I'm a big fan of stock points, just for full disclosure ).

Control box ?!? Again, I am using the Dyna S setup...No control box or module, just the plate that replaces the points & condensers...

Really if someone knows of a good 5 ohm coil to recommend, lemme know.

Gordon · « **Reply #6 on:** January 09, 2011, 03:35:00 PM »

Quote from: Eydugstr on January 09, 2011, 03:14:50 PM

Really if someone knows of a good 5 ohm coil to recommend, lemme know.

What's wrong with the Dyna 5ohm coils?

Spanner 1 · « **Reply #7 on:** January 09, 2011, 03:42:03 PM »

Should have said 'pick-up thingys'..... ( that replace the points ). There is a Dyna box too, it's a spark booster thing, rather like Hondaman's ignition mod.

Gordon · « **Reply #8 on:** January 09, 2011, 04:08:24 PM »

Quote from: Spanner 1 on January 09, 2011, 03:42:03 PM

Should have said 'pick-up thingys'.....

I think the technical term is actually "pick-up thingamabobs". "Doohickeys" would also be accepted.

Roach · « **Reply #9 on:** January 09, 2011, 05:15:32 PM »

dont know if the same problem happens on the 750 as did on my 550 but. when i ran my dyna s with 3ohm coils my bike would drain the battery so fast once it started i dare not let it turn off now im running the 5ohm and works perfect

5ohm are black
3ohm are green

ksmith0034 · « **Reply #10 on:** January 09, 2011, 05:18:38 PM »

I am using the Dyna 5 ohm with my Dyna S on my '71 CB750.

Duke McDukiedook · « **Reply #11 on:** January 09, 2011, 05:28:38 PM »

The 3 ohm dyna coils killed my killswitch, I recommend using the 5 ohm coils with these bikes.

swellguy · « **Reply #12 on:** January 09, 2011, 08:39:33 PM »

Quote from: Industrial-sized Dukiedook on January 09, 2011, 05:28:38 PM

The 3 ohm dyna coils killed my killswitch, I recommend using the 5 ohm coils with these bikes.

Looks like I'll be making some changes, thanks!

Bluegreen · « **Reply #13 on:** January 09, 2011, 11:13:17 PM »

I have the green 3 ohm coils. Noticed a difference. Love em. Already had the Dyna S when I installed them.

swellguy · « **Reply #14 on:** January 10, 2011, 01:09:42 AM »

Quote from: Bluegreen on January 09, 2011, 11:13:17 PM

I have the green 3 ohm coils. Noticed a difference. Love em. Already had the Dyna S when I installed them.

Can I ask what difference? I've installed a kit that came with the with Dyna s and the 3 ohm coils as part of rebuild so I havenlt fired up the bike yet. Just curious what you're seeing.

Roach · « **Reply #15 on:** January 10, 2011, 01:28:13 AM »

best thing to do is test it it seems to be pritty hit or miss with the 3ohm some guys have it work others don't worst thing that could happen from my testing is a dead battery but that you will probably run into after a block of riding.

the 3 ohm when i tested it said that it was charging my battery while it was running but as soon as i turned of my bike it barely had enough juice to get it going again.

Duke McDukiedook · « **Reply #16 on:** January 10, 2011, 07:19:03 AM »

Quote from: Bluegreen on January 09, 2011, 11:13:17 PM

I have the green 3 ohm coils. Noticed a difference. Love em. Already had the Dyna S when I installed them.

There is no performance difference between 3 ohm and 5 ohm on these bikes, the 3 ohm just places a greater load on your already anemic electrical system. Greater chance for electrical failure.

Eydugstr · « **Reply #17 on:** January 10, 2011, 09:20:45 AM »

Quote from: Industrial-sized Dukiedook on January 10, 2011, 07:19:03 AM

There is no performance difference between 3 ohm and 5 ohm on these bikes, the 3 ohm just places a greater load on your already anemic electrical system. Greater chance for electrical failure.

Yeppers that's what I hope to avoid! I read it somewhere on the forum about this being an issue.

Quote from: Gordon on January 09, 2011, 03:35:00 PM

Quote from: Eydugstr on January 09, 2011, 03:14:50 PM

Really if someone knows of a good 5 ohm coil to recommend, lemme know.

What's wrong with the Dyna 5ohm coils?

Absolutely nothing! After reading stuff on other threads and everyone's opinions/experiences on this one, will go with the Dyna's. Basically just wanted to hear what other guys were using with the Dyna S ignition.

Jeff.Saunders · « **Reply #18 on:** January 10, 2011, 01:01:35 PM »

5 ohm is best on the early Hondas.

Steve F · « **Reply #19 on:** January 10, 2011, 06:37:14 PM »

Quote from: swellguy on January 10, 2011, 01:09:42 AM

Quote from: Bluegreen on January 09, 2011, 11:13:17 PM
I have the green 3 ohm coils. Noticed a difference. Love em. Already had the Dyna S when I installed them.
Can I ask what difference? I've installed a kit that came with the with Dyna s and the 3 ohm coils as part of rebuild so I havenlt fired up the bike yet. Just curious what you're seeing.

When I built the bike, I was using the DYNA-S and DYNA 5 ohm coils and had a tough time keeping it from "stuttering" and not running in top form. I switched to the 3 ohm and OMG what a difference. Bike is smooth, idles amazingly and is peppier (is that a real word?). I might add that I'm using LED's for everything, and an H.I.D. headlight to bring down the load on the alternator so charging has never been an issue. Revs all the way to red line without missing a beat. I love the DYNA-s and coil combo.

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Author Topic: Dyna S Ignition system, street bike - What's the best coil? (Read 5668 times)