XR400 head gasket

[Martin Blair]

If you have a 10.8:1 piston with the xr gasket it should run 11:1 or so? Also this gasket should be able to halde the comp if the head is down right? And where do I find one for a 416 bore or do I have to trim it?

[quadmxracer]

you should beable to use an oem honda gasket with out modifications.

[04'400ex'er]

Originally posted by HN400exracer
If you have a 10.8:1 piston with the xr gasket it should run 11:1 or so? Also this gasket should be able to halde the comp if the head is down right? And where do I find one for a 416 bore or do I have to trim it? You are right about the gasket, It is thinner than the EX gasket, bumping up the compression a little. About the 416, I dont know if they mke one for that bore, but you should be able to trim it. Others with this setup, please chime in on this.

[Holeshot36]

Yes the xr gasket will raise the comp. a little bit and it will fit without any mod.

[cals400ex]

a 10.8:1 piston won't be over 10.8:1 unless the piston was cut to the wrong ratio. a true 10.8:1 will be 10.8:1 with the xr head and base gaskets.

i don't remember exactly, but i thought they recommend a larger head gasket when you get a 416 or larger. i think with a 406 or stock bore, you can use the stock head gasket. actually, many people run the stock one on their 416's and even 426's, but it isn't recommended and i wouldn't. so, i believe the cut off is a 416 for a larger diameter head gasket, but i am not positive. the xr BASE gasket will fit right on if your using the stock sleeve.