cam chain lunch

I'm pretty sure my engine just ate the cam chain. I was riding along happily when I heard a really loud nasty rattle, pulled over and then there was a sickening crunch and the engine seized. I kind of want to die a little. The bike was running soooooo well too! What's the best/worst case I'm looking at now?

Best - Something else came loose, maybe a cam chain rubbing block, that has wedged itself into a spot that stopped things. Maybe it will be easily retrieved an d replaced, and life will be good.

Worst - Cam chain broke. All the valves are bent, head is cracked, all the pistons are chipped, the crank is twisted, transmission gears are missing teeth, and the crankcase is broken, plague is released, global warming is real, everybody dies.

I suppose you could drain the oil to check for metal chunks, and if it doesn't look too bad, remove the cam cover and take a peek.

I hope it isn't as bad as we all suspect it is.

pull the valve cover asap. if the can chain is messed up or no longer there then remove the cams. you will be able to see if all of the valves are closed or not. if one or more valves are stuck down then.... it's time to grieve and plan the funeral arrangements.

Yeah, that all sounds about right. If things are salvageable and the plague won't be released, does the crank case need to be split open to replace the cam chain?

The only good news so far is that it looks like there are plenty of KZ550 engines available for not too much $, worst case.
Trying to stay positive here.
I adjusted the valves about 1000 miles ago, wondering what I could have done to kill my bike. It has a manual cam chain tensioner; maybe the tension was too loose or tight.

Holy crap, best case scenario!!! I took the valve cover off and it didn't take long to figure out what was going on - the two exhaust cam sprocket bolts had come loose and wedged themselves in a groove.






Everything else looks pristine. I have no idea how or why they would have come off - I never messed with them, but I just went from a possibly totaled bike to a couple dollar repair. Whooooooop!

Glad you found the problem, but before you get too Whoooop bear in mind you might just have caused some exhaust valve or piston damage.

Where you are now I'd just replace the two m6 flange bolts with some threadlock, and see if it runs ok.

Never seen that before, when i read it earlier it seemed a really odd one -from running nice to lock up.

Even rattly camchains or dodgy tensioners usually go on for a long time.

Hopefully as the motor was idling at the time you may have just dodged a bullet here.

Worst case scenario is a bent valve(s) and a mangled piston crown, the 550 mills are cheap as chips so replacements are easy and cheap - Good luck!

Yeah, after my initial elation it occurred to me the exhaust valves might be jacked. Maybe I should take off the exhaust cam and check to see that all the valves are level. If one is bent I could do more damage just by running it, correct?
Still, man, could have been so much worse!

That's encouraging news. With the new sprocket bolts installed and the spark plugs out, you should be able to turn the crank by hand to see if there is any undesirable contact. If ny, you could do a leak down or compression check to neck for valve sealing. I do.t know if it is true on the 550, but on the liter bike's the engine can be turned with a 17 mm wrench on the timing plate end of the crank.

17mm correct, try turning it by hand and if it is smooth then that is a good start.

One of those things you will know pretty soon when running it if things are wrong. No point stripping everything and spending dough on gaskets and oil seals when you are half an hour away from hitting the start button.

Worst case a cheap GPz550 mill, maybe with the milder midrange tune zr cams could be a cheap and easy fix.

Bad luck mate - this is very rare and the first I've heard of this, been into these 550 motors for 25 years. Use threadlock on the M6 bolts!!

Yeah, it's kind of a crazy thing to happen. When I adjusted the valves a while back I did notice the timing was off half a link, which implies somebody was in there before who didn't know what they were doing. Maybe they messed with the cam sprocket and didn't torque it to spec. I don't know, hard to understand how this would happen otherwise.

I'm still waiting for the parts. I know, just a couple of standard bolts but I'm pretty religious about replacing everything with genuine Kawasaki parts. I'll let you all know how it plays out. I'm hopeful the engine will be OK and joy will return to the land.

I guessed it may have been messed with by a previous owner, explains the very unusual problem you have.

My first GPz550 was slightly out on the cam timing, i put it back right and was a nice improvement.

The 550 mills seem to have quite generous valve/valve and valve/piston clearnaces, a lot of motors wouldn't tolerate that.

I even spun my tuned GPz550 well out of the redline following a missed gear, again, not many motors would tolerate that.

Keep it at, these 550's are so smooth running and strong and I hope you have dodged a bullet on this.