Topic: Plug gap recommendation.

[Loctite77]

So I am getting ready to replace the entire ignition system on my 76 750F This is what I have.
pamco electronic ignition
ultimate high output coils
NGK DR8EIX Iridium plugs
NGK Resistor plug caps.

I run KandN pod filters and the carbs are jetted a little larger at 115 with the clips in the lowest notch and an open pipe.

I've done a lot of searching and reading and have seen recommendations from stock (.24-.28) up to about .32  so I'm wondering what you guys think? I'm leaning towards the larger gap but if I do what would the symptoms be if it's too large? I don't do a lot of spirited riding, just around town and open it up good on occasion.

Thanks!


Yeah Son!

[Loctite77]

Anyone?!


Yeah Son!

[NewOldSchool]

Always gapped mine at .28, never had an issue.

[flybox1]

+1
.28

[Deltarider]

The idea of a sparkplug is that it only has to ignite a tiny amount of mixture around it's central electrode.Then and from there the fire spreads through the combustion chamber. Any sparkplug can do that igniting. Second task a sparkplug has to fulfill is to keep it's nose clean so it can keep on doing its first task. Manufacturer has picked the right sparkplug that will stay clean in the rpm range of use of that particular bike. If you open the gap too wide of a conventional spark plug, electrodes will erode quicker. An iridium plug claims to erode less or hardly at all. I am eager to see independent test results that will prove iridium plugs do a better job apart from staying good longer.

[PeWe]

Different jetting with irridium plugs?  Or is this kind of plug better for racing than street?

My bike did not like irridium last year. I do not remember which I used, NGK or Denso of recommended model to CB750. Started to run unevenly on low throttle lift. Plugs looked like a little bit rich. Caps were NGK 5kohm. Hondaman ignition with TEC points, plug gap was 0.7mm.
I read somewhere that 0.8mm can be used too with high powered coils and electronic ignition

Carbs were not too rich. Changed back to NGK D8EA and it ran much better except that I had to go richer on pilots which I found out after a 280km day trip in low speed, 70-90km/h.