Z1 valve seals exploded - why?

1974 z1.
- weisco 1015cc / .400” cams / ported
- ape valvetrain
- keihin crs29 carbs
- dyna / kerker etc...

I noticed the other week I was hearing a little metallic noise at idle. Very sporadic and seemed to go away.
I thought... weird, the bike is running great and feels great. Maybe it’s my imagination.
After some more riding through the week, I dumped the oil, and found a ton of ultra fine tiny metal debris around the magnet drain plug.

Also there was a weird little piece of metal as seen in the below photo that was in my oil that looks like a paper clip of some sort that got shredded through the motor? WTF. I thought it was a piston wristpin circlip that popped out but nope, all mine are in tact.

I just took the motor apart. Looks like 2 valve seals exploded. See pics below.
I have the red Viton seals, its def them.

Why would this happen?
I don’t think the bike was lean or running hot. Great oiling up top. Nothing appears scored or burnt.
The valve seals are only 3 years old, along with my redone head.
The bike has been running great for about 3 years. I’m extremely frustrated.

I guess I’m going to split the cases and double check everything to confirm what happened. And clean any metal debris. I’m not a happy camper, so any input as to why this could have happened is appreciated so I can prevent it next time.

Thank you.
Ed

Bucket hitting seal because of high lift cams or the seal popping off the guide?  

I would think that those two seals were not firmly on the guides and got smashed between the retainer and the guide. 

When you get the valves out you should have a better idea. Like if some of the seals are still fastened to the guides but the tops are beat up would suggest a clearance issue. Very curious. Keep us updated.

Did you pop your head off yet?? You got my curiosity up on why your motor eat your valve guide seals.

I ran Yoshimura Super Bonneville cams that have .410 lift. I do run 650 style retainers and buckets with Kibblewhite valve guides and O.E.M. Kawasaki valve guide seals in my one head. My valve guides are installed to match the height of stock valve guides. I never had a valve guide seal get damaged by the retainer or come apart. And I use 10,500 for my shifting point too!!

Did your fancy valve guide seals seem to slip on to the guide without much effort?? I always push my valve guide seals on with my fingers. You can feel when the ridge on the inside of seals slides over the boss on the valve guides. I never liked any of the aftermarket valve guide seals out there. I put my last motor together with O.E.M. valve guide seals I bought back in 1983!! When I took them out of the plastic bag, they were still nice and soft even after 34 years of sitting in my parts box!!! After about 8~10 hours of running no sign of oil smoke from my fancy motor in my Superbike.

I like how clean the inside of your head looks. Somebody changes oil a bunch!!! Thats the way it should look inside your motor!!

That's why i use BMW valves, valve guides and seals with a metall ring in my head. They never blow off or come loose and coast 20 Euro a set of 8 valve seals.

Looked to me the outside spring retainer got caught on the inside spring somehow.
Steve

I have not taken the valves out yet.
Anyone have an idea what the paper clip metal thing could possibly be from?

The paper clip metal thing belongs to the bottom circlip of the valve seal.

The "paper clip " is the distorted plain metal spring clip that helps retain the seal to the valve guide.
It is clearly seen here In the pic.
Spring for the valve stem at the top and the plain clip for the guide at the bottom.

Ok, I’m going to replace the valve seals myself.
Did a quick test and none of my valves leak, so I should be good.

Is there a brand valve spring compressor tool that works best on a kz head?
Brand / link would be appreciated. I need to buy one.

If you want, just send it in and we will change out the seals and vacuum test it for you.