hey, i'm posting for a friend, he's blown 2 head gaskets the past month and where getting pretty tierd off it, he is pissed to the point of selling his bike lol!, What the heck are we doing wrong, is their something we can do different.
this is what he has in his engine

- racing hot cam stage 2
- big bore 440 11.1 compression
- port and polish
- Yushimura complete pipe
- dynojet kit stage 2

My idea was to put double gasket for the head, it would lower compression a bit, im guessing he'd lose maybe 2-5hp but at least they wouldn't keep blowing! we always torqued the bolts to what they were supposed to.

 

Have you guys talked to the guys that make the big bore kit
My bet is they have seen this before
That is a fairly popular kit
But as I remember it does take special gaskets
Wiseco does show a Big Bore Gasket Kit
Possibly even talk to them
Good luck
Ray

 

Is he still on the 10mm studs?

 

maybe you should get stronger head bolts, and you have the wesico gasket right?(or whatever piston u used)

 

yes we used the gasket thats made by wiescow for the big bore kit, the bike works frikkin awsome when it does but man, it can't be normal the going threw so many gaskets. That is something that i mentioned to him before to change the head bolts he never did thow

 

This seems to be very common with 440 kits! I can only see doing a 440 if it has been bored out so far that it is the only option you have left. As a performance mod, better to go buy yourself a 450R and be done with messing with the EX!

 

head studs most likely the problem. go to gt thunder or duncan racing they sell them and talk about them alot. put them in as well as heavy duty tinming chain. Both seem to have problems stretching and or pulling out with the added power,compression,and heat.

 

yhea, he's already got an aftermarket timing chain in, don't remember the name though but its something good