Suzuki Ltz400 problem, (Atv expert not needed) anyone with engine knowledge.?

I took my quad for a ride today, it's a 2005 ltz400. It's got a wiseco 13:5:1 piston .20mm bore and a L.A sleeve. The mechanic i take it too did a whole topend rebuild a few months ago. The whole lot, valve's, spring's, etc. I was very starteled today when i took it out i put it under a load and in about mid-range the engine kicked back pretty hard, but didn't stall. Now the guy said he left my vales loose to seat into the head? Im not so sure if that's correct. But it still tick's like all hell and he says that's cause he left them loose to seat, im supposed to be taking it back here in a few day's so he can adjust them. Is this serious, or could this be that they are ready to be adjusted? I need some input. It seems like it's firing before TDC. Maybe a bad coil? Someone please help.