head gasket AGAIN (im about to kick this thing...)

[TC426EX]

Well, I am thoroughly DISGUSTED and out another race... My quad blew yet another head gasket. Against my own best judgement I went ahead and put a Cometic in it when I split my cases last time (for the broken shift shaft). I put a new set of Laeger tie rods on today and fired my bike up with shorts on and felt a hot blast of air against my left leg. I knew right away what it was... The cometic looked like crap to me since it was just a 3 layer gasket. I know the good gaskets have a ring along the inside that prevents blowing out like this one did. I already have the heavy duty stud kit, and I checked them, so thats not the problem. Last time I rode it I DID make somewhat of a mistake... I used premium pump with some octane booster instead of race gas in my 12:1 and I have a feeling that the high temperatures from it detonating a bit might have contributed to this. Any thoughts? I KNOW octane booster is terrible but I just wanted to use it this one time to save a run to the dealership for C-14. I need to know what the best head gaskets everyone has used are and which come with the metal ring along the inside circumference. White Brothers?? Tudors?? Let me know your experiences so I can order ANOTHER one monday...

Im about to change this thing one more time and if it blows again Im gonna have to look at getting the head milled and cylinder decked...

[turnandburn]

i would be checking the cylinder and the haed surface for warpage first. xr400 gasket

[trxmaster]

Originally posted by turnandburn
i would be checking the cylinder and the haed surface for warpage first. xr400 gasket

Deff true everything up first.

Cometic does offer a gasket for higher compression with a steel ring, but normally recomends it for 13:1 actual comp and higher.

Do you know your true or actual compression ratio?

There is also a guy on ebay selling a one piece that he claims will not leak for around $25 so you could check that out too.

[416rider]

on my old 400ex I had the same problem when I bored my mine out and I had new bolts put in and put in heli coil in the engine and stopped the head from coming up and blowing the gasket.

[TC426EX]

I already got a heavy duty stud kit which is supposed to be as good if not better than the heli-coils... Im definitely going to check those surfaces... anyone else??

[airheadedduner]

I use a powroll head gasket. They take a stock one and mill it. Mine is set to accept my 89.5 piston. I ran it, took it apart, put it back together. Still Holding:D

[K_Fulk]

Originally posted by trxmaster

There is also a guy on ebay selling a one piece that he claims will not leak for around $25 so you could check that out too.

I bought one of these for mine. Its a bored honda gasket not sure if its from an xr or ex. Hope fully it will hold up.



I was gonna get some heavy studs but im not having a stud pulling problem, just a sealing problem. Heck maybe ill just get the studs anyway? I kjust dont like paying $70 for bolts.

Got my head and cylinder decked also so hopefully i shouldnt have any more problems.

[EXtremeEXer50]

the same thing happened to my friends who bored his out...he wound out trading it in and buying a 450r!

[papaw]

i think if you have a good flat surface (i.e. head and deck)the less gasket you have the less problem you will have with blowing gaskets.thats assuming you have good studs not letting the head and cyl. seperate. i dont know if it will work in a 400ex (still working on it)but has worked on a toyota 4 cylinder motor.