400ex head gaskit

[biff440ex]

I keep having problems with the head gaskit blowing on my 440ex. I normally use a cometic gaskit but i think i want to try a copper one. The problem is I don't know where to find one. I also would like to know if this is a common problem.(the head gaskit)

[1fst400]

ya, it hapends lots in 440 kits from what I hear.


I blew the head gasket in my motor. A motor builder said to have my head decked at a machine shop.

[400eXr1d3rZ]

get a xr400 gasket

[ww228king]

xr400 and trx400ex is the same gasket kit.....

[F-16Guy]

One or more of your head studs (probably the forward one) is pulling out of the aluminum threads in the cylinder. It's a weak point on the 400ex. You need to send the cylinder to GT Thunder and have them install a set of oversized head studs. The studs are larger in diameter, have a longer grip length, and the threads in the cylinder are modified by compressing the aluminum to make the new threads. This makes the metal around the threads more dense, which makes it stronger. Mine took about a week, and the workmanship was very good. It will probably run you a little over $100, but it's money well spent -- unless you like tearing your engine apart.

[F-16Guy]

Originally posted by ww228king
xr400 and trx400ex is the same gasket kit.....
The XR head gasket is about .015" thinner compressed.

[ww228king]

on my cometic gaskit kit that i have gotton .....it list xr 400 and trx400ex ...so that is why i said that it was the same

[ww228king]

c7626 is the part# fits 1999- 2005trx400ex (440ex) 89mm and 1996-2005 xr400 (xr440) 89mm

[F-16Guy]

It probably is the same for Cometic, but the OEM gaskets are different.