Hi all, i'm new to the forum, a quad bike converted dirt rider now with my first used 2008 WR450F. The prev owner looked well after the bike but didnt do any free mods and as i couldnt ride the bike after i bought it due to a busted knee figured id do all the free mods: ais removal, grey wire mod, snorkel out, o-ring mod, etc bike's got an fmf ti on. The bike always fired first kick or swing, but after going on dirt trail it started sputtering and backfiring and wouldnt go again. i pulled the carb at home and found a 175 main jet ( i thought too big but bike ran well) cleaned carby and put back in. The bike fires once, sputters, then backfires and dies. i pulled the carb many times now to make sure i didnt miss any dirt, i dropped the fuel, changed to the suggested 168 main jet for my area, still no starty. So yesterday i filled all day and changed the plug back to the old one i replaced and the bike started first thing, ran beautifully, took it around the block, dies half way so me pushy back. Change out plug again to new one, what do you know, it works again. So at this point i believe my problem is on the actual plug that clips onto the coil pack that sits on the plug as it works fine every time i WDF it. Has anyone heard of this, does it make sence? I must add that on the dirt trail the the problem increased every time i went trough water untill the bike eventually died. I have now degreased the plug and wires, dried it and siliconed it up nicely, hopefully IF my diagnosis is correct my prob is solved, but i would love some forum guru opinions.