The M8 plug is the NGK version of a 1/4-32 spark plug...They are overpriced and don't work as well as the Rimfire plug sold by C&H....Best thing tomy could do is change to CM6 spark plugs...The Chinese version of the 1/4-32 plug works well, better than the M8, but not as good as the Rimfire....
One of my customers has thousands of hours on small 4 stroke gassers using these plugs, we KNOW what we're talking about...
The Rimfire is the world's BEST 1/4-32 spark plug....
If tomy is using the M8 he's making a big mistake...