when my friends 94 cbr600 runs it makes a whistling noise like it has a supercharger or somthing. could this be caused by a vaccum leak?

 

Shouldn't be hard to locate the source of the sound.... But it could be coming from anywhere on either the intake or exhaust side of the motor.

Check the airbox, carbs and exhaust

 

One easy, kinda shadetree, but effective way to locate that type of noise is to take about a 1 or 2 foot long piece of vacuum hose and hold one end to your ear, then poke around where the noise sems to be coming from with the other end, if you locate the specific area of the noise or vacuum leak, you'll definitely know it.

 

what???

I cant hear you!