XR400 cam install going bad....

[CranMan]

Well I'll cut to the chase here...I was taking the head cover off my 99 400EX to swap out the cam with a XR400 cam...and I was removing the 12- 6mm bolts, when one of them broke off in the head. I know what you're thinking, I probably did something wrong, but I'm a mechanic with almost 15yrs experience, and the bolt just broke. So now I get to try and figure out what to do, because it's one of the bolts that's in a recessed hole, and it's going to be a little tricky. Worse case I'll pull the head off and take it to a machine shop, but I dont wanna do all that!!! :mad: Maybe if I end up pulling the head of, I'll just go ahead with a 416 kit, since it will be most of the way torn down anyways. Oh well, life goes on I guess....:(

[400exRacerX]

You can't take the head off when the valve cover is still on. Try a easy out or reversed thread drill bits.

[Guy400]

About your only hope is an EZ-out and if that doesn't work you'll have to drill it out and retap the hole.

[Adams44]

Is it one of the long ones the threads into the cylinder? If it is just one, you can run without it. I stripped one of the long ones last year in between races and ran it like that until the summer break, then helicoiled it. I think you should be o.k. if you don't have time to take it down.
I am not saying you shouldn't do it right, but I ran 2 GNCC's with it like that and it held.
And when you fix it...time for some anti-sieze...

[CranMan]

I did get the head cover off, the bolt broke off in the head, and all the other bolts came out fine. As for a EZ-out, my only concen is messing up the head. If I screw it up, I get to buy a new one. If the shop screws it up, THEY get to buy a new one. Since it would cost $300 for a new head, I'd probably be better off paying someone to take the chance....And yes, anti-seize is going to be used when it goes back together :)