xr400 head gasket

[brianC400X]

I've read that an xr400 head gasket is .020" tall and that the 400ex head gasket is .030". Has anyone installed an xr400 head gasket on a stock bike. If so did the ten thousanths of an inch make difference? I am considering this mod for my wheels.

[cals400ex]

i have not done this but from what i hear, it will raise your compression by two tenths or so.

[lansing400ex]

I put the XR400 headgasket on my 400EX along with removing the base gasket. I used RTV silicone in place of the base gasket. I noticed more power from low end to midrange. I did this one year ago and have had no problems. Its one of these cheap and easy modifications to make. I added an engine oil cooler mimicking the four stroke tech set up at the same time with the XR400 headgasket.

[brianC400X]

have you had any leaks at all from the base of your cylinder?

Originally posted by brianC400X
have you had any leaks at all from the base of your cylinder?

yeh what he said

[lansing400ex]

I have had no leaks at the cylinder base. I spread a thin layer of RTV silicone on the contact surfaces. I then let it dry and harden some for about 15 minutes before placing the cylinder on the block. Once the two halves were together I let it dry another 15 minutes before tightening the cylinder down. By doing this you make sure the RTV will stay in place and not squish out sealing nothing.

My understanding is that by removing the base gasket and using the XR headgasket one will gain .30 of squish. I used my stock cam when I put it back together and the gains were definetly at low end and midrange.

[F-16Guy]

My only thought on removing the base gasket is to be very careful about how much gasket maker you use around the top end oil passage. If you get too much "squeeze out", you could potentially block, or partially block, the oil passage. If this were the case, you could wipe out a cam/rockers in short order. I think you've got the right idea by letting it set up a little before installing the cylinder, and also by using a thin layer, especially around the passage.

[cheetah]

But in order to get the benefit of an xr head gasket, you must replace the base gasket with silicone, correct?

i don't think so.

[toby400ex]

Doesnt this just increase compression:confused:

yup. and the xr gaskets are easier to blow.

[cheetah]

So you do not have to use silicon?:confused:

no dude silicon is for the base gasket. If u use silcon it will give u a few more tenths of compression. The xr gasket is the head gasket. so u get more compression from the silicon and the xr gasket.