I am having some trouble with my Yz400f. It started to get hard to start and was running rough so i checked the valves and a couple needed adjusting. I got the clearances all within spec and it went ok for 10 hrs or so but i went for a blast in the woods and hit a tree branch in a wash-out and it broke off the tiny drain hose on the bottom of the carby and hasn't ran since that ride. It ran a little rough that day after the wash out but didn't stop completely but still hasn't started since. I have pulled the carby and given it a spray with carby cleaner and blown the passages with a compressor. I fixed the drain tube and tried to kick it over but it seemed dead. I took out the spark plug and it was covered in soot and fouled up so i replaced it and it started after 2 kicks. It sounded a bit rough so i let it warm up for 2-3 mins and went for a blast down the drive way and it died within 100m. Fouled plug again. I took that one out and it seems to have oily soot?? I then repeated that same process again with a new plug and same result:banghead: I am using cr8e plugs as it says in the manual. I am puzzled? I have very limited mechanical knowledge but i'm just using my manual as a bible. It's worth its weight in gold. lol. I thought fouling plugs was a 2-stroke problem? I cant find much on the subject any help would be much appreciated.