Motorcycle Repair: Suzuki running rough, suzuki gsx 1300r, vacuum system

Question
A friend's Suzuki GSX 1300R (2002?) has a rough spot in the RPM range of 1200 to 2000 when the motor is lugging.  Iddle and power are good and the bike is fine in all other respects.  Do you think the problem could be in the vacuum system?

Thanks for your help.

Answer
Hi Jeff,

I don't suspect any problems with a stock Busa with the symptoms described. It's how this engine may respond to acceleration while in too low gear. I would expect symptoms similar with lugging the engine.

Avoid lugging the engine, stay within the power band. The result may be undue wear on the engine and drive train.

Have your friend modify his/her riding habits and monitor the symptoms. Chack back with me if necessary.

Happy Holidays!

Respectfully,
Mark Shively