TOPIC:

Search option tells me Gexex electronic ignition you gap sparky plugs to .065. Can anyone verify this with actual instruction manual.

Thanks in advance

gregz

GregZ wrote: Search option tells me Gexex electronic ignition you gap sparky plugs to .065. Can anyone verify this with actual instruction manual.

Thanks in advance

gregz

I will look and see if I can find mine Tuesday and let you know.

Do you need any Gerex parts ? I have all but good coils

Dave

Hi Greg

I found the original Product install / tune sheets from my Gerex Ignition

Spark plug gaps are to be .063 to ,065

Hope this helps

Dave

Perfect Thank you !

IMHO, doubling the plug gaps does not increase ignition performance but will SIGNIFICANTLY reduce coil life by doubling the voltage on the secondary windings. I run a CDI and always have run the standard .032" gap.

bountyhunter wrote: IMHO, doubling the plug gaps does not increase ignition performance but will SIGNIFICANTLY reduce coil life by doubling the voltage on the secondary windings. I run a CDI and always have run the standard .032" gap.

I hear what you are saying , but Greg asked for what Gerex put in their instructions

Dave

Street Fighter LTD wrote:

bountyhunter wrote: IMHO, doubling the plug gaps does not increase ignition performance but will SIGNIFICANTLY reduce coil life by doubling the voltage on the secondary windings. I run a CDI and always have run the standard .032" gap.

I hear what you are saying , but Greg asked for what Gerex put in their instructions

Dave

I was just warning him what it's going to do to his coils.

Does Gerex supply coils with their system? If so, maybe they are constructed to handle the 40kV voltages that's going to generate but it's going to really kill a standard coil.

Gerex when they were selling CDIs of my vintage was 30 plus years ago and YES they did have matched coils as part of the package.
I still have mine but one cracked where the spark plug wire fit into it
Last time I talked to Joe Hopper at Pit stop about 2 years ago he had some used Gerex brand coils to sell me ,
but I went with a Dyna system instead to modernize my ignition system.
Also according to Joe only early models of the Gerex CDI worked well like mine did for 30 years. Later models were prone to premature failure which was believed to be after Gerex changed hands and the quality went down hill This statement is 3rd hand info.............
P S I kept my spark plug gap at .035 and it worked fine even under high boost conditions

Dave

I have yet to see any evidence that forcing the spark plug voltage higher by widening the gap does anything good for performance. If there was even a single HP to be gained, bike makers would have been doing it for decades but they don't. The energy delivered in the spark is 1/2 L (I) squared which has absolutely nothing to do with the voltage that the spark jumps at. Same energy, slightly longer spark but gas burns the same.

bountyhunter wrote: I have yet to see any evidence that forcing the spark plug voltage higher by widening the gap does anything good for performance. If there was even a single HP to be gained, bike makers would have been doing it for decades but they don't. The energy delivered in the spark is 1/2 L (I) squared which has absolutely nothing to do with the voltage that the spark jumps at. Same energy, slightly longer spark but gas burns the same.

It's not about spark energy. It's about the amount of air-fuel being initially ignited. With a larger gap, the initial flame kernel is bigger, and thus the entire mix will take less time to burn. This allows you to use less advance, and still get the burn completed for best power. But there is diminishing returns to this. If it were to burn too fast, it would just hammer the piston and more would be lost as blow-by and heat. You want the burn be a smooth increase, then decrease in pressure.

And of course, as you said, it is really hard on the ignition system.

My only evidence is seat-of-the-pants. I had neglected my plugs for a long time. In the city I don't get a lot of full-throttle opportunities so it was not an issue until one day, I went wide-open-throttle at higher RPMS, and it was as if someone turned off the kill switch. I could also hear loud ticking... the sound of spark discharge under the tank as the sparks were finding an alternate path of less resistance. As soon as I let off the throttle, it resumed firing.

So I checked the plugs and the gaps were about 50% larger than spec. This might also explain why the bike was knocking slightly more, when giving too much throttle on a hot day, on the highway.

The only thing I did was replace the plugs with new ones. Now I could go full throttle with no problem. But I definitely felt the bike was not as lively as it had been, even just the day before.

I've also found a few articles, many years ago, about enlarging the spark gap, but I didn't make copies of it. I think John DeArmond might have written them.

To get the longest life out of the coils and igniters, I run standard gaps.

Dave - While searching around for a replacement for my recently dead Gerex, I came across this post in august 2016. Hey, that's like yesterday to a classic Z guy! Any chance you still have the Gerex?

zinnco wrote: Dave - While searching around for a replacement for my recently dead Gerex, I came across this post in august 2016. Hey, that's like yesterday to a classic Z guy! Any chance you still have the Gerex?

Im pretty sure I do. It should be on a shelf in the basement work shop
Dave