Sparkplug Gap

Just covering the details here.
What is the correct gap for NGK BP6ES & BP7ES plugs with a Boyer ignition? Is it still the factory setting of 0.028in?

And while I'm asking little questions, waddya reckon is the best psi for a set of 4.10x19 TT100 K81's with a single rider of 80kg?

If you are running the stock coils then I'd stick with .028" gap. I run a RevTech dual tower coil (Harley type coil) which really puts out a monster spark and have increased to .035" and it works fine.

For tire pressures I don't think you'd be too far off with 28/28. If I remember right I think the riders' manual called for 26/26.

Cowboy Don said:

What is the correct gap for NGK BP6ES & BP7ES plugs with a Boyer ignition? Is it still the factory setting of 0.028in?

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Boyer Bransden do not recommend any increase in plug gap as far as I'm aware.

Cowboy Don said:

waddya reckon is the best psi for a set of 4.10x19 TT100 K81's with a single rider of 80kg?

Click to expand...

I run them at 28F/30-32R but then I'm a bit heavier than you (90kg).

i run bosch plugsset at .40 with the boyer , stock coils, single mikuni. starts 1st kick, runs great. was told awhile ago that ethanolcrap gas runs hot, so increase the gap. can't recall who told me that

thanks Guys
Whoops, forgot about mentioning the coil. Dual output single coil, not sure of the brand, yellow unit. All modern electrics, high output alternator, the Boyer's the oldest bit. Aren't being force fed ethanol in South Australia yet, only one chain of servos are offering it so far as I know.
Would be interesting to see other opinions on this gap issue, eh?

So the tires are pretty standard, I would normally run 30/32 on a streetbike, or play around that area. I'll experiment. I would like to go for a pair of Avons, something a bit grippier, but these K81's are pretty brand new and there's no sense in spending money there yet, I'm sure something else will need attention.

Run as large a gap w/o missing or burning up the ignition. The ranges listed are zones to try, then can fiddle with indexing the position of the gap in relation to mixture swirl.

On tires older harder need less PSI than newer softer tires, but about always will want ~2 lb less in front, or so front gives least fight back with the rear. You are in for a surprise someday if you'd not played on low air or already know what a flat feels like at 70 going straight as an arrow, until anything changes the pure bee line steady power...

For what it's worth, at least in dragsters, alcohol fuels run cooler; some gas/ethanol combos may have a higher octane rating so you can increase the ignition advance which may make you run hotter.