Help!!! I have a 38 Mikuni Carb on my 2000 Wolverine. I run a K&N filter, with the AirBox top drilled out, a Big Gun Exhaust and minor engine performanc parts. I'm having a problem when you open the throttle up at a low RPM, it basically bogs out and quits..At higher RPM you can crack the throttle and it screams. I've put a different piolet jet in the carb. Stock, it had a 37.5, and I now have a 50 installed (keep in mind i've gone up in 5 size increments). It has some improvement, but I still can't crack it from an idle state. I've gone up to a size 60, but I think it's then getting to much gas so I backed down to the 50.

Any Ideas???

i would try going back to the stock pilot jet. the pilot jet affects the system from idle to quarter throttle

I think it will be difficult to jet a 38mm carb on the Wolverine. The problem you described is typical when too large a carborator is fitted to a motor. I've seen it done lots of times with snowmobiles, people going from 34's to 40's. Yes, it makes it scream at full throttle, but it never works right at part throttle settings.
From what you describe it sounds like it's too rich at low revs, so I would suggest going with a smaller pilot, and dropping the needle. THat might lean things out a bit. The drilled airbox is already helping, I'm sure it wouldn't run with out that.
Where did the carb come from? Is it a flat slide, round slide? Is it of a 4-stroke or a 2-stroke?

Good luck with this. Let us know if you can get it to work, I'm always looking for ways to get some more out of my Wolverine.