What is causing my 1990 Kawasaki Vulcan 750 Motorcycle to lack a lot of power?

Tune up, change plugs, clean (or replace) air filter, adjust valves and carbs (if needed). Clean the float bowls for added insurance.|||Check your vacum lines especially the one on the right air filter make sure its not bottomed out . This can cause the problems your talking about...|||Tune up, change plugs, clean (or replace) air filter, adjust valves and carbs (if needed). Clean the float bowls for added insurance.|||Dirty carb, intake system, dirty injectors, a lube job.