with just over 4000 km on it. has exhaust leak at muffler flange ( new one on order), anyways last summer it ran well.. once and a while it fouled a plug. i read something about the slide needle wearing out so i replaced it this year. seem to run ok. recently i had it out got ran it in a bit of water. and it started to spit and sputter a bit. fouled a plug changed it ran ok for a bit. started to backfire a bit just off idle. so i cleaned the carb didn't seem dirty. started and still backfire off idle and until about 1/4, 1/2 throttle, took it out and did a plug chop off wide open, the plug was white.. i don;t know why tho . i don;t have a fuel blockage, and i never changed the main from last yr... really puzzled
i noticed tonight that around the head gasket its starting to seep a bit of residue.

anyones info greatly appricated