Gaskets Thicknesses and Compression?

[08400ex'er]

Right now my motor is torn apart with the head (outside) and outer fins being ceramic coated with a heat emitting coating(pulls heat out). Before they get back I am trying to work out what gasket size/compression ratio I want to run. I currently have the JE 10.6 piston and an Cometic EST gasket set which is .027" thick. My question is what is the stock head gasket thickness, what is the stock xr400 head gasket thickness and could I step down to the next/thinner cometic gasket which is .018". What would my true compression ratio's be at each and what is the max dynamic compression I can run on 93 pump gas.

From what I have read on the site a quench area of .040 is best. How do I calculate this?

Other mods are Stage 2 cam (lowers dynamic compression)
Ceramic coated piston/head/valves
Larger oil cooler 13"w/4"Tall/2" thick
CFM oil tank

[CJM]

The best gasket to use is the XR400 gasket, its thinner than the cometic or the stock gaskets, I am not sure the exact thickness however. I do know that if you use that headgasket it will give you way closer to the true compression.

Or you can deck the head, but that requires machine work.

btw, what oil cooler are you using. Ive been looking for an oversized one that will fit good.

[08400ex'er]

In the Articles section in the Ask Mickey article he says standard gaskets are .040, the XR400 is about .30. The Cometic Est is .027 I just want to verify these are correct and the resulting compression ratios plus what I would get with a .018 gasket.

I am using a Setrab model 50-613-7612 with an AN 8 90 degree fitting on the outlet side and an AN 6 straight fitting on the inlet. I used the stock oil cooler fittings and made a plate for the new oil cooler to mount up to.

[CJM]

I just measured my cometic base gasket, its .027 inches thick. Would that extra little bit the .18 gives you be worth it-might, but the .027 is already there and already lower than the XR400 gasket.

FWIW I have been very happy with the cometic brand gaskets

[trxPOWER]

just fyi, you can run 11 to 1 compression on 92 pump gas.

[supertrooper90]

basically through my research when I built mine to get the best quench area leave the bottom base gasket out (use hi temp rtv) and run an xr400 head gasket. If you do some searching you can find info but its all old stuff and a lot to wade through. I have a 416 je 10.8:1 and I did this and my bike runs killer!!! I run 93 octane. I trail ride, mx, and harescrambles.

You want to shoot for as close to zero deck height as possible. I dont remember the exact numbers, but the ex piston is like .040" in the hole. Leaving out the base gasket brings you closer to the zero deck height numbers.