Ok so this will be my first post here after reading tons of threads to assist me I finally need some expert help to my situation. The bike in question had a leak in the right side crank seal that was pulling tranny oil in to the cylander and causing lots of issues, plus had a decent number of hours on the bike so I rebuilt the engine, new piston, rings, sent off the top end to be replated, the works and changed out the seal. Not knowing much about jetting I bought a JD kit and went with the manual recommendations and sure enough it was too rich and was fouling plugs left and right. Since then I have returned jetting to stock, 165 main, 40 pilot, stock needle in clip 4, aircrew 1 turn out, since that was never an issue before crank seal leak. Bike ran fine for a few tanks then I went to start it one ride and it fouled immediately after start up. I'm just feeling a little stuck right now after so many hours of work and don't know where to go from here, could the crank seal still be leaking? And if not what should I be checking? Bike is rode in the trails no track riding in Florida so no elevation and I run 50:1 mix with the recommended oil. To sum it all up should I keep playing with the jetting or do I need to tear down the engine again, bike feels great when running, then all the sudden fouls a plug. I know it been a long post and if you got this far I really appreciate the time you have taken to read this and reply. Any opinions or help would be great I'm at my wits end with this bike. Thanks!