Okay need some help, i just had my banshee in the shop, they put in all new main seals and case seals and re-jetted my carbs they also re-sealed the intake manifolds and repacked the toomey silencers, i also just put in a brand new modquad cdi box cause my stock one went out. The bike was running great and i took it out for the weekend. The second day of riding i took it up to the drags and opened her up, i did like 3 back to back races down the drags and the bike ran fine except the last race when i was fully pinned out, the bike stalled out but i started it back up instantly, we then headed out for some duneing and while i was riding the bike started backfiring from the left cylinder. so i swapped out the left plug in the dunes and rode back to camp. But the backfiring still kept happening so i parked it for the weekend and when i got back home i check a couple things that i read in topics about backfiring like: Split flywheel, plugs, spark, obviously jetting is good i just had it done, and i check for any visible leaks around the intake manifolds and exhaust. Is there any way a reed cage could be broke or could i have blown a head gasket or is there a leak some where? I am going to start with a compression check and if i find nothing i am going to do a leak sown test. but i am new to banshees and am not too sure what is going on. Does anyone have any advice or ideas as to what is going on?