Motorcycle Repair: xr650l cheap mods flat at high rpms, air fuel mixture, plug colors

Question
Hello, I got a 2000 XR650L this summer. I did mods recommended by peoples in chat forums, I removed airbox snorkel, shimmed the needle with a 0,030" washer, drilled the carb slide to 5/32" and I rejetted with Keihin 55/158 jets and put a uni-filter, the bike has tons of low rpm torque but I can't get it over 85 mph. I heard it's supposed to hit 95-100 mph easy. It feels like power gets flat as rpm's get higher. Is it normal? if not, what would you check first?  Thanks in advance for your time!
Martin, Quebec Canada

Answer
Hi Martin,

You'll need to tune the carb for more top end performance. Change the main jet one size at a time and note performance changes. Read spark plug colors to see what affect the changes have made to the air-fuel mixture.

Send me an email address as requested. I'll return several files on carb tuning.

Respectfully,
Mark Shively
Dayton, Ohio