According to an engineer of the green spark plug company Sunbeam supplied the Model 9 engine with a Champion D9 18mm 1/2 inch reach spark plug
reason beeing that the shorter plug in a longer 3/4 hole would prevent fouling of the plug....
feel free to react on this.
greetings, Hennie
Was that just because they don't have any long reach plugs in stock?
I have tried both in my Lion 600 and so far can see little difference in performance. I was hoping the long reach plug might improve the tickover that is sometimes a little difficult to tune.
The Long reach 18mm plugs are like rocking horse manure....
Personally I prefer the 3/4 long reach, and agree with the article in last Beaming. Better flame propargation, especially when using a more sporting setup.