Blaster Head Gasket Problem PLEASE HELP

[justin_yfz450]

Hey, Last night I put togther a Blaster for my friend. It has everything in the top end new. Reeds, Bored. 20 over, wiseco piston, and all new gaskets etc etc. Well when we went to start it I heard a whistling noise. It was the head gasket because it fired and then smoke came out from al around the head gasket. So we tore it back down and put on a diferent head gasket. Once again it done it. Next we took it back apart and then cleaned it up really good. Yes it done it once more. I cant figure out what would make it do this whenever its all new gaskets and stuff?? Any of you guys got any suggestions?

[42F67N]

You mean the base gasket that mates the cylinder to the lower end?

If so are u using them cometic gaskets that have the dimples on them,ive rebuilt a few blasters and have found them cometic gaskets with the dimples suck in my opinion specially around the reeds,a factory yamaha gasket is better in my opinion.

I would suggest cleaning the gasket surfaces really good make sure you have the gasket on correctly"it is poss to put it on wrong " and make sure you torque the bolts down correctly using a criss cross pattern,before firing the engine do a leak down test pump the motor up to 7 psi and let it sit for 10 mins while performing the test spray around the base gasket,head gasket and reed cage with a soapy spray if it has a leak ull deff see exzactly were its coming from,or u can just watch the guage for 10 mins and see if the psi drops.