double base gasket/thin style head gasket

[farmer250r]

my buddy who used to race 250rs back in the day was telling me they used to use a double base gasket and a cr style thin head gasket to get more power out of a smaller cc motor.he used it on his stock cylinder.i was wondering if theres any PROS VS CONS on this setup due to my 250r blowing a head gasket.i wanted to check my piston and rings and ring gap anyways so i just tore it down to the bottom end.my bore looks good and so does my piston and rings.i do have some porting done.i didnt get it ported but imo it feels like a mid to top end port job.im wondering what the double base gasket will do.will it help.or should i jsut run stock gaskets due to my porting.i forget the name of the company that ported it but ill check the engraving on the jug.any info would be great.thanks

[Motofool250r]

not sure why you'd want to run two base gaskets and a thin head gasket unless you had interference issues with the head

the idea with the thin cr gasket is to increase compression a tiny bit.

[Langbolt]

What this does is Increases both Exhaust & Transfer Port timing - more top end

If the base gaskets add the same as what the head gasket removes....in thickness....your compression will stay pretty close to original

This is a cheap way of checking wether the roofs of your ports need machining before you actually cut any metal.

If you cut them and it ran worse....you'd have a junk Cylinder....but this way you just remove a base gasket.

:devil:

[Motofool250r]

Originally posted by Langbolt
What this does is Increases both Exhaust & Transfer Port timing - more top end

If the base gaskets add the same as what the head gasket removes....in thickness....your compression will stay pretty close to original

This is a cheap way of checking wether the roofs of your ports need machining before you actually cut any metal.

If you cut them and it ran worse....you'd have a junk Cylinder....but this way you just remove a base gasket.

:devil:

learn something new everyday

[RyanWsly]

correct about changing port timing, but it also raises the compression. this is generally done on a unported cylinder.

[wilkin250r]

And there would never be any reason to do this if your cylinder was ported correctly.

[TLR-Online]

This is on CT's Website:

TRX250R Cometic Top-end Gasket Set with CR Style Head Gasket - 68mm (stock cylinder)

This is a great little hop up trick for a stock 250R. This head gasket is paper thin at only .011 thick. It actually would raise the compression a bit too much for pump gas, so we supply two base gaskets raising the cylinder up slightly. This acts like mild porting. It sets the compression for pump gas and picks up about 4 HP with a wider power curve and more bottom-end power.

[farmer250r]

so since i have porting done to my stock jug i should just use the stock gaskets?

[etccb]

You won't need the double base but you may want to run the CR head gasket. Confirm which head gasket was installed when the work was done to your cyl. It may have a CR head gasket on it now.

[trs9102]

Just be aware of your compression running a CR gasket. Wouldn't want to seize because you needed to run VP.