I just got a 92 900rr and took it out for the first time. It was freakin great, except for one problem. Between 4-5000 it would hesitate and stumble a bit, either at a steady speed or accellerating through that rev range. Everywhere else the bike is great. The bike has a slip-on (HES, High Energy Systems), and a K&N drop in. Apparantly the bike was rejetted too, but I can't remember with what. There is a lot of soot inside the can, so I am thinking it's rich. It was also sitting for 4 months without drainging the gas.(Not by me though!)I live in Calgary, Canada (altitude about 1000m, or 3000ft), any suggestions as to what way to go with the jets? Would getting a header and/or individual K&Ns lean it out enough?

 

If its still running rich even with a k&n and jets its either your filter needs reoiled and cleaned or the jets might have been installed wrong.

 

Mid-range problem... carburetor slides. Adjust the needle length, assuming your bike has a jet kit. The stock needles aren't adjustable. Aftermarket ones (included in jet kits) have a clip that can be moved up and down the needle which makes it longer or shorter, and in turn adjusts when the slides opens and closes.