trmtuning

hi guys got a slight problem with my vr knocked the sump off a few weeks ago and destroyed the bottom end. So bought a second hand engine off ebay which sounded good 2 go. Put the engine in on saturday and its missfiring like mad popping back through the air box and got a horrible noise like the chain hitting the case every now and then. I think the chain has slipped wot are the chances of re adjusting the chain then all being well or can i expect valve damage. Cheers.