Z1 cam caps
Jesus fucking Christ. Just when I think the z1 is solid and done, something else breaks.
The first gen KZ motor has a weak spot. The caps which hold the camshafts down and in place, have shitty bolt holes. They’re m6 threaded holes in the soft aluminum head. The sequence for removing the cams and installing the cams almost guarantees you’ll potentially strip out a couple bolts. As you tighten the cam caps down, it’s essentially pushing a valve open, so you can’t always guarantee it’s going in smoothly. Combine that with the fact that the service manual has the wrong (overly tight) spec for how much to torque them down.
Everyone on kzrider says to go super light or hand tighten them only. It’s the number one fuk up on the KZ motors that everyone fuks ups. Especially if you have high lift cams, which I have, it extra aggrivates the risk.
Anyway, long story short: I heli coiled a couple holes about 4 years ago, and had Larry C fix a couple holes when he ported my cylinder head. (Shoulda had him do all 16 holes).
It’s been exactly a year since my last engine rebuild. Bike rips and has been super solid. The other week while on a Thursday ride I instantly heard a super loud valve noise from left side of my motor.
I limped the bike home, and pulled the valve cover the next morning. Turns out, that out of no where, for no reason, 4 bolt holes on the exhaust cam stripped completely out. Fuk.
So, with Nates help, pulled motor out of frame and gonna heli coil them myself without taking the head apart. If I can’t fix myself without taking head off, I’ll break engine completely down and take it to Mar auto to have them fix the holes.
While the motor is out I’m gonna clean a bunch of shit up and paint my frame gold.
I’ll update once I try and fix the holes myself… See how it goes. When I put heli coils in 4 years ago, I didn’t loctite them in… but I’m thinking about using blue loctite on the heli-coil itself so it never moves in the fresh cut head threads. Thoughts anyone?
4 responses to “Z1 cam caps”
Published - Mar 26, 2014
If you didn’t figure it out already, you probably need to pick up an old enduro. Holy shit they’re fun. As a graphic designer I can’t stop looking at these old ads. They’re so great. I love the ones with the crazy colors. Of course your dad bought a yamaha enduro in the early 70’s. […]