...and yes, gap DOES matter.

So how come the Betas use such a cold plug, ie. NGK '7' heat range as opposed to the NGK '5' that most others use? Is it because of design differences in the engine, like higher compression or different squish band design, or is Beta just more conservative in this regard than the others? Anybody have any ideas?

OK, here's the skinny on how I've managed to completely cure the pinging on my Rev-3 AND find a little bit more top-end power as well. I am not a mechanic, neither am I any kind of authority on fuel, spark plugs or jetting so I have no idea if this will work for anyone else:

NGK BP5ES spark plug. Standard pump unleaded petrol mixed at 85:1 with Ipone fully synthetic oil and 5ml of STP octane booster per litre of petrol.

I tried the octane booster route first because super unleaded is very difficult to obtain 'round here.

Regarding which brand plug is best to reduce knocking, I'm curious: Are you guys comparing a new plug of one brand to a new plug of the other brand? That would be the fair way to do it, IMHO.

It really wouldn't be a big surprise if a new plug worked better than an old one, would it?

I recently cured my bike of knocking by replacing the plug - with the exact same brand and type of plug.

The latest edition of Trials Competition newletters does an expose' on factory rider Ray Peters' BETA 270 / 280 - it states that he is running the NGK BP7ES... and V-Force reeds, instead of the Champion plug.