Hello all. So I put a new motor in my DRZ (last one locked up) and took it on a few rides, all good. Rode it about 500 miles one day then went to take it to work the next day and after about 20 miles it started surging and backfiring really bad. Parked at work and went to ride home and couldn't go over 3000 rpm (estimate) without it backfiring like crazy. Got it towed home and didn't touch it for a while. Just now got to diag on it. Unplugged the stator and it still has the issue. Removed the spark plug and didn't see any marks on the boot indicating it grounding through it. Checked spark and it looked kind of weak(I'm an automotive mechanic so I'm used to real heavy spark). Tried switching tank to prime and no change. The bike runs perfect at idle then just starts backfiring when up above idle. I kind of suspect fuel but I hate installing the fcr39 so I refuse to pull it out until I know for a fact there are no other issues. Any other things to check? I have someone coming over saturday so I can try swapping the cdi box.