ORIGINAL: togatoga
I don't have any problems with both my engines, the plugs fit.Only thing is I used the OS type F plug, didn't try out the supplied redline plug though. The backfiring is an issue for me right now, its caused the demise of 2 plugs.
togatoga,
I was just pondering your backfiring problem and it occured to me that earlier in this thread you said you were using 20% fuel.
The compression on my engine is pretty high. Perhaps 20% is too much for such high a compression.
I would give 10-15% nitro a try to see if it relieves backfiring.