RGS Spark Plugs

[alanp]

Normal BSA recommended plugs for 9:1 pistons/Spitfire cams on an RGS is Champion N4. NGK plugs have an equivalent B7ES.
I have fitted the slightly hotter NGK BP6E vee grooved electrode plugs on my newly rebuilt engine. These ran really well on my 500 Gold Star avoiding sooting/fouling up after much experimentation. I know they are two different engine conditions but has anyone any experience of the slightly hotter plugs on this engine, before I start racking up the miles and holing a piston or two?
Cheers, Alan

[muskrat]

G'day Alan,
               my book says B77EC but I can't find them down here. I have found B8ES's work well and a little cooler. Even 9's on hot days with high cruising speeds. But in saying that I have gone back to 7's as I have been richening the mixture to combat pinging. 6's will be my next step.
It's a matter of suck and see. Go with 7's to start and IF they soot up go to 6's.
When racing I would warm up on B7ES then throw B9EGV's in to play. The "p" means protracted electrode and might run a little hotter again.
Cheers

[cus]

G'day Allen,
I started off running 7's on my S/R, but they fouled up fairly quickly, especially if I started
the bike in the shed a few times or did some in-town riding, so went to 6's. Still get a miss
fire or two if I've let iot idle for too long, but find they are perfect colour after a good long
run. I used to use Irridium plugs in my Trumpy, they're great plugs, but not available in the
6 equivalent BR6IEX..."I think" only BR7IEX. I'm pretty sure I could solve the problem with
another slide 3 1/2 maybe or a longer needle, but happy with the way it runs on the open
road, doesn't seem to heat up much, no colouring on the header pipes after 2 thousand miles.

regards, Cus

[BSA_54A10]

When BSA recommended those plugs, they were for burning a mythical volatized fluid known as petrol.
This substance has not been available for many years so BSA's recommended plugs do not mean any thing unless you run your bike on 1960 "petrol".
If you do then please tell me where you get it from.
If however you try to burn the light fuel oil with some light volatiles added, commonly called "fuel" that we get now days, then you will need to use plugs capable of igniting this "light oil" and remaining hot enough to stop slightly heavier parts of the  "light oil" depositing themselves on your electrodes shorting the plugs out.

So you need to go at least 1 if not 2 grades hotter.
Also you need to stop the engine by draining the bowls so none of the oil gets sucked into the engine without a spark happening and deposits this "muck" on your plugs.

[MG]

I'm using NGK's VX spark plugs (B9 in the iron head A10 and B7 in the alloy head A7)
Those plugs work great, the bike will idle for ages without sooting (Well, that's what they were designed for according to NGK)

However, I can highly recommend these. Miracle plugs if you ask me 

Cheers, Markus

[Triton Thrasher]

Still get a miss fire or two if I've let iot idle for too long,

That sounds like a rich idle, rather than a plug problem.