So I bought a 2009 KLX a couple of days ago. The previous owner told me he tried messing with the jetting multiple times but couldn't get it perfect. The bike pops a lot on decel, and when I checked the sparkplug it was black, which I find odd. I swapped in a new sparkplug and will take a look at it once I put some miles on the bike.

The bike hesitates in 2nd gear when ripping the throttle mid-way, it loses power for half a second then kicks back in.

The previous owner has done the following:

- Removed snorkel
- FMF Q4 with spark arrestor
- No clue what he did with the mixture screw
- Idle screw is set at 2k RPM. I tried dropping it to stock settings (1.3k), but she wouldn't start.
- Dynojet kit (not sure which one he has installed)

I'm also looking into buying an extended fuel/air mixture screw so I can tinker with the carb. However the koubalink ones are out of stock. Any other screws available out there? Preferably in Canada as well, since shipping form the US gets expensive.

I guess my basic question is, what do I do now and where do I start? I've never messed with jetting before, but am fairly mechanically inclined (did the doo-hickey on my KLR650, valve adjustments, fork seals...etc.)