Dyna S coil voltage question

Yea did that already but no reply, bought them anyway as I have had a lot of good components from Accel over the years. Probably like you say 35K or close.

I never had much luck with accel coils when i worked in the dealership we encountered a lot of failures with the accel coils. I have always had much better luck with the dyna coils.

DesertWizardB1 wrote:

...The thing that makes me mad is that I'm pretty sure I did this to myself as the last time I checked the compression I must have forgotten to remove the wire that powers the coils...

Ouch, yeah that will do it.

The Accel 3-ohm have plenty of voltage as long as they get enough dwell. They are slightly slower than the stock electronic ignition coils. I use them with no problem up to 10,000 RPM with 10:1 compression, but my motors are stock and I keep a stock spark gap. Raising the compression or using a much larger spark gap may require the faster Dyna 2.2 ohm coils.

loudhvx wrote:

DesertWizardB1 wrote:

...The thing that makes me mad is that I'm pretty sure I did this to myself as the last time I checked the compression I must have forgotten to remove the wire that powers the coils...

Ouch, yeah that will do it.

Ok....stupid question time....why do you have to disconnect the coils when you do compression tests?

If you don't, a high risk of overheating the coils is there. A "cooked coil" can develop cracks letting in moisture for internal shorting, possibly stranding you on the road sometime.

Where the ignition coils are mounted traps heat under the gas tank, getting stuck in slow moving traffic is another bad thing as the coils need a flow of cooling air just like the engine does.

MFolks wrote:

Are the coils too old to be covered by a Dyna warrenty? I wonder how a set of Accel coils would work with the Dyna "S" system.

The coils are 5 years old so the warranty is over.
In regards to the question asked by link14.
"Ok....stupid question time....why do you have to disconnect the coils when you do compression tests?"
When you do a compression test you pull a plug to insert the compression tester gauge. This means you disconnect the coil wire from the plug and probably just let in hang not connected to anything. If you don't remove power to the coils or at least ground the loose plug wire I think what happens is the voltage builds up in the secondary much higher than normal as it has no path to ground and can fry your coils or modules. I guess I'm just getting forgetfull as I get older One thing I'll never forget is how much I love to ride this old bike :laugh:

Link14 wrote:

loudhvx wrote:

DesertWizardB1 wrote:

...The thing that makes me mad is that I'm pretty sure I did this to myself as the last time I checked the compression I must have forgotten to remove the wire that powers the coils...

Ouch, yeah that will do it.

Ok....stupid question time....why do you have to disconnect the coils when you do compression tests?

Well, actually you can leave the coils connected if you connect them to the plugs and make sure the plugs are touching each other.

As DesertWizard said,
Usually, when doing a compression test, you pull at least one, but sometimes all, of the plugs so the motor cranks over faster. When you do this, you usually have the plug wires unconnected for convenience. If you then crank the motor over with the ignition trying to spark, the spark energy has nowhere to go externally. The energy must get dissipated in the coil internally. The voltage in the coil gets very high and breaks down the insulation inside the coil. Then arcing occurs in the weak spots in the insulation. If the arcing is repeated, the conductor will eventually get burned leading to high resistance. Eventually it may "open" leading to a reading of no continuity (infinite resistance). (However, it may still generate a weak spark if the arc can jump over this "open" spot.)

DesertWizard also makes a good point in that the ignition module can get fried from too much primary voltage... yet another major concern.

Another failure mode for points or Dyna S ignitions, as Mfolks said, is heat. Some ignitions can leave the coils powered up even when the crank is not turning. If you forget, and leave the ignition turned on, the coils can overheat. In extreme cases they can melt.

All this can be avoided, and battery power is slightly higher, if the coils are simply disconnected on the primary side during compression tests.

Thanks, hopefully I didn't screw up the 900 too badly. I'll disconnect the coils next time.