Well it didnt take long to blow that expensive cometic head gasket. I replaced it with a tri-metal one, and since stock compression is 8:1 and I'm now 10.25:1, my guess is that the stock torque spec of 18lbs isn't enough so I went 25lbs. Has anyone elso has problems with a Wiesco high compression and blowing head gaskets? And am I doing right by cranking the head on a little tighter? I've had this thing apart so many times I could write a bolt by bolt tutorial on tearing the top end down and putting it together from memory. That and these engines are bullet proof, so I wouldn't think an extra 7lbs would distort anything too much.

 

I'm surprised that you didn't pull the studs out. My experience of small engines is the studs can let go with the standard torque, never mind 30% more than they should have. Are you sure the head and cylinder were flat to start with? No gasket will hold on a warped surface. If they do need flattening, I prefer the grinding paste on a sheet of glass method as machining ups the compression even more.

 

I think merryman called it with warpage. Even if they are new, check them.

At some point, you begin to exceed the limits of stock head clamping, so with enough boost or compression, some engine builders have to O-ring the head or block, but i really doubt 10.25:1 would dictate this unless the stock clamping was pretty sorry to start with.

 

Well I wouldn't have any reason to think they aren't flat. The engine ran fine when I tore it down, just smoked. The valves and seats were ground and pressure checked, came back %100. I havent had a troubles as yet, but thanks for the info, I'll keep this in mind if I have any more blow outs.

 

Sure you do: blown head gaskets!

It might have been little enough to hold the 8-1, but now that you are putting more pressure ( literally ) on it...the weak point shows itself.

If it fails again, i almost guarantee this is the problem.

Also, make sure there are no dowels bottoming out...or the studs aren't running out of threads.

 

I guess i should have clarified why I dont suspect warpage, the machine shop i use is very thorogh, d the gasket wasn't blown when I took it apart. But I do get your point, I lol when you said "sure you do, you got blown gaskets!"but I think it was just not torqued down very well, and not tight. I think it was more my torque wrench needing its legs stretched after sitting so long, it is a "clicker" wrench. I haven't had any more probs, but its cold here in Indiana and I dont ride much, my son however will find any weaknesses lol. Thanks for replying I'll keep yall informed if I blow-out again. And thanks for the bottoming out idea, I hadnt thought of that, that's why I love these threads!

 

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Ah...now it all makes sense...