1983 vf750f interceptor

bought this bike cheap, they wanted more power, bike was running. they had cylinders bored 40 over put back together and could'nt get timing close enough too finish putting back together so i bought figuring they didn't follow the manual. so i followed the manual to the tee three times and still the #4 cylinder exhaust valve hits the top of piston the same problem they where having any tricks that i'm missing? never mind fixed it my self found out that the clymer manual was a real piece of s@#% never buy clymer nothing but trouble,