Mishap installing cylinder head cover KZ750 Twin

I had a mishap installing my cylinder head cover the other day. I had just installed a new head cover gasket and was in the process of torquing down the bolts when one snapped in half. I removed the head cover and managed to drill out the old bolt. I retapped the hole and proceeded to install the head cover. When I got to torquing down a new bolt in the retapped hole, a piece of the head broke off, leaving no place for the bolt to secure to. Any ideas or quick fix suggestions or do I need to replace the entire cylinder head?

OUCH, that hurts,, were you using to much torque or was the new bolt too long? A picture would help us to help you with the problem.

I was torquing it to the exact specs that were in the repair manual. The replacement bolt was excactly the same as the original. I'll take some pics and post them by tomorrow.

I have to wonder if this is another "Misprint?" in the manual,telling you to torque those bolts down to some ridiculous amount,like 12 foot pounds,or something.

What WAS stated in the manual?

I had the same problem with mine but only piece of the theaded hole came off and I don't necessarily torque those screws, I just snug them just to seal the cover from oil leaks. Don't really know what to do and my only plan of defense or cure right now is to get a new head, but thats expensive, plus probably new valves and...... I forgot the little bearing pieces on the valve stem. Lets wait for another opinion

Sandy wrote:

I have to wonder if this is another "Misprint?" in the manual,telling you to torque those bolts down to some ridiculous amount,like 12 foot pounds,or something.

What WAS stated in the manual?

My 750 twin manual calls out the ridiculous value of 95 - 113 inch-pounds, which is about 9.5 foot-pounds maximum. I figured out early on that is way too much, which is why I never stripped a bolt yet. IMHO, about 50 - 60 inch-pounds is plenty, but I actually torque mine by feel using a short 10 mm wrench.

grndprix69 wrote:

I had a mishap installing my cylinder head cover the other day. I had just installed a new head cover gasket and was in the process of torquing down the bolts when one snapped in half. I removed the head cover and managed to drill out the old bolt. I retapped the hole and proceeded to install the head cover. When I got to torquing down a new bolt in the retapped hole, a piece of the head broke off, leaving no place for the bolt to secure to. Any ideas or quick fix suggestions or do I need to replace the entire cylinder head?

Which bolt is it? I just looked at my twin, looks like most of the bolts you could sneak a nut under the bottom if you had a longer bolt and cleared the threads out of the hole.

Is there enough head left to support a nut?

bountyhunter wrote:....My 750 twin manual calls out the ridiculous value of 95 - 113 inch-pounds..... I figured out early on that is way too much...[/quote]

That's correct, but is it too much? I've set mine to that over and over on both bikes and it's been fine so far. I always thought it was pretty loose.... weird...
:dry:

Do you guys loosen your cam chain before installing the cap? I do...

Biquetoast wrote:

bountyhunter wrote:....My 750 twin manual calls out the ridiculous value of 95 - 113 inch-pounds..... I figured out early on that is way too much...

That's correct, but is it too much? I've set mine to that over and over on both bikes and it's been fine so far. I always thought it was pretty loose.... weird...
:dry:

Do you guys loosen your cam chain before installing the cap? I do...[/quote]

IMHO, 100 inch-pounds is right for the camshaft mounting caps but too much for the valve cover bolts. YMMV

I used to make cover gaskets out of gasket cork material and 100 I-P will crush one of those to disintegration. Another thing: the OEM cover gasket is a thick rubberized paper gasket. Over the rubber end plugs, the gasket will deeply depress the rubber there because the 100 I-P is severely compressing the gasket everywhere it is between two metal surfaces. Where it is metal over rubber, the gasket does not compress and it forces the rubber plug down. That "step" in the gasket is why so many bikes leak oil around that plug.

I have another head if it comes to that- I hope it doesn't:(

Thanks for all the replies. I'm sorry it took so long to get back here. I tried to take a picture of the problem, but my damn digital camera isn't working right.

Bountyhunter pretty much summed it up. The torque ratio is way too high.

The best way I can describe the part that broke off is to have you all visualize the top of the motor. It's a "H" shape. The part that broke off is the screw hole at the lower right hand corner of the H. The bolt has nothing to screw into because it the screw hole is broken in half.

I was thinking of reversing the bolt, putting a washer on each end, and tightening it down with a nut or cap nut.

Does this sound good?

grndprix69 wrote:

Thanks for all the replies. I'm sorry it took so long to get back here. I tried to take a picture of the problem, but my damn digital camera isn't working right.

Bountyhunter pretty much summed it up. The torque ratio is way too high.

The best way I can describe the part that broke off is to have you all visualize the top of the motor. It's a "H" shape. The part that broke off is the screw hole at the lower right hand corner of the H. The bolt has nothing to screw into because it the screw hole is broken in half.

I was thinking of reversing the bolt, putting a washer on each end, and tightening it down with a nut or cap nut.

Does this sound good?

If there is enough metal to support it, that sounds like a plan.