Page 1 of 2

Twin wasted spark charge up time

Posted: Mon Dec 10, 2018 4:41 pm
by skelly
Seasons greetings everyone.

Hoping some of you may be able to help with some dwell figures for me.
I run a S40 on my motorcycle, its fitted with a pair of Dyna 2.2 ohm grey twin output coils and runs wasted spark as many motorcycles do.
The coils are mounted over the engine, under the fuel tank in the usual place and are bolted to the frame in the usual manner.

I'm just curious if anyone can give me an idea on coil on time ?
In the software I can adjust it from 1000 to 4000 microseconds.

Any ideas ?
Cheers.
Skel.

Re: Twin wasted spark charge up time

Posted: Mon Dec 10, 2018 5:47 pm
by stevieturbo
Test with a current clamp and scope to see where current peaks and levels out. That is your number.

Re: Twin wasted spark charge up time

Posted: Sun Dec 16, 2018 3:34 pm
by skelly
I don't have those things sadly.

Re: Twin wasted spark charge up time

Posted: Sun Dec 16, 2018 5:35 pm
by stevieturbo
Then there isnt really any way to guess.

Other than a lower number will be safer. Too high can potentially burn out the coils.

Re: Twin wasted spark charge up time

Posted: Mon Dec 17, 2018 2:50 am
by Rob Stevens
You could try reducing the time until you get a misfire and them up it a bit. Or ask Dyna for the technical data.

Re: Twin wasted spark charge up time

Posted: Fri Dec 21, 2018 3:57 am
by skelly
I did ask Dyna.
They were totally useless and wouldn't provide me with any meaningful info at all.
They suggested it was the responsibility of the ECU manufacturer to supply such info.
Bit rubbish really.

Re: Twin wasted spark charge up time

Posted: Fri Dec 21, 2018 4:20 am
by Antral
I would try at 2500ms and look at the spark then increase slowly if it looks too weak.

Re: Twin wasted spark charge up time

Posted: Fri Dec 21, 2018 7:43 am
by stevieturbo
It's up to the user of any product to determine how they need to use it, especially when using it in a non standard application.

Re: Twin wasted spark charge up time

Posted: Fri Dec 21, 2018 8:39 am
by katana
stevieturbo wrote:It's up to the user of any product to determine how they need to use it, especially when using it in a non standard application.
How is using an aftermarket coil, designed for a bike and used in wasted spark configuration any more non-standard a configuration? Dyna should know the data for what voltage and time they optimally charge - they've been making them for nearly 50 years! Why would an ECU manufacturer know what coil a client will be using to predict optimal dwell time?

About the most useful reply so far is - 'start low (2500us) and compare sparks'. adding 100us at a time - at least it's subjective!

Re: Twin wasted spark charge up time

Posted: Fri Dec 21, 2018 11:36 am
by skelly
Agreed.