Suzuki bandit 400 did massive backfire and now doesnt run right, any ideas what

it could be?
Hey guys just bought this 1991 GSF400 Bandit from a buddy and it ran great and was kinda quick, well I let a friend who claimed to be superman on a bike ride it and I heard him reving it way up as he was going and then a LARGE backfire and then the sound of the motor was going revv revv revv revv and then a few minits later he came back and the bike was running normal but the end of the exhast was blown half off and one of the screws holding it on was missing. I put it back togeather and it still runs but it doesnt sound the same or have the same power and when I get on it, it hesitates and stuters and just don't get it like it use to. Ant ideas to what he did to it and what I might need to do to fix it? Thanks again.
 
Back
Top