If you suspect it is runnig lean then find a nice long quiet bit of road, run it at a constant speed for a mile or two, at the rpm you suspect, then cut the engine on the kill switch and pull the clutch at the same time. Cost to a stop, being gentle with the brakes, they are a lot more fierce without the engine running. Pull out the plugs, if they are very pale brown or even white then it's running lean and you needmore fuel in there, if they are dark or sooty then less fuel is indicated. What you want is a nice buff colour. It's known as doing a 'plug chop' ask anyone who rides a tuned two stroke, they generally have this nervous twitch when asked.
