Motorcycle Repair: ENGINE KNOCK, crankshaft bearings, connecting rod bearing

Question
MY SON-IN-LAW PURCHASED A 1997 SUZUKI 600 GSXR. OWNER WAS HONEST AND SAID THE ENGINE HAS A PROBLEM. ENGINE IDLES GREAT, BUT ENGINE KNOCKS WHEN IT'S REVVED UP. WHAT'S THE REMEDY BESIDES "WELL DON'T REV IT UP"? IS IT ANYTHING SOMEONE WHO HAS REBUILT A MOTORCYCLE ENGINE (ONCE) CAN FIX? APPRECIATE ANY INFO YOU CAN PROVIDE. THANKS IN ADVANCE.

Answer
Lou,

-it could be a few things but sounds like
it might be a bad connecting rod bearing.

-Try using a long screwdriver or mechanics
stethoscope to pinpoint the area the sound
is coming from. You could remove the clutch
cover and see if anything looks wrong in there.

-It would be a big job to fix but possible with a
repair manual for the bike.

-the lower engine case must be removed to
service the crankshaft bearings.

-If the crankshaft journal is damaged it could
get very expensive.