Porting...jetting...spark plugs? YARGH!

There should be no leak from the sparkplug. A new plug should have a decent gasket that will crush to seal it. Perhaps the threads are almost stripped & needs a helicoil or the surface the gasket seals on is damaged & needs to be draw filed smooth & flat or on the off chance the plug hole had been drilled on a slant & the plug meets it on an angle.

Some bikes like RMs specify plugs that are less prone to vibration damage. The tip is likely to fall off & damage the engine in this model from time to time. Cough up the bigger dollars for the right plug is my advice.

Do a search in the RM forum & you might get some starting pointers for jetting but really you should do some reading on the subject & experiment on the safe side.

Tip of the day -Ignore revs. The different jets are matched to throttle position. Once you make this mental adjustment jetting is not so hard.

Your washer may be beat on the plug,put a new plug in after it is snug,turn the plug with a plug wrench no more than a 1/4 turn.This is all you need,do not tighten until you can't turn anymore, this will kill the washer .