200 12:1 Piston-Blown Head Gasket

[Tyler Scruggs]

Just got my 200 together with a ported head, Wiseco 12:1 piston, Cometic head gasket, running on 110 octane racing gas. Within 3-4 minutes of idling and adjusting the carburetor, gave it a few revs and blew the head gasket under the carburetor. Is there a specific head gasket I need to run with this high compression piston or are they fool proof and its more than likely the head is not true?

[lazybiker79]

Not that I know of.. I've had a 12 to 1 piston in my old 200x for years with no problems. Did you torque the head bolts to spec? How are the head studs? Have the head studs threads sterched?

[MTS]

Wiseco used to make a steel gasket for them, if I remember right.

[shortline10]

You need a copper head gasket !!!

[NINJA]

My 86 never blew it's head gasket with 12:1 compression. I was using Vesrah gaskets. Like Lazy said, did you torque to spec, did you inspect the studs and nuts, did you check the head for warpage?

[Dirtcrasher]

You need a copper head gasket !!!

I like that too!

Your top of your cylinder may not be perfectly flat as well as the head; They may need to be resurfaced.

Sometimes cylinder sleeves stick up just a few thousandths and cause head gasket problems also.......

A spotless smooth surface, perfectly flat won't cause you any issues.

What bore are you on now or how many mm's or thousandths over stock size piston are you using? Not compression, the overage of the bore?

If it's been bored a bit, does the head gasket you run accommodate that size?