Broken clutch friction disc

I pulled the clutch out today to inspect it. I really haven't been having any trouble with it, but I'm in the process of rebuilding my engine with a 1075 kit and wanted to check it out. The last friction disc to come out of the basket had about a two inch section that was broken out. The broke off piece was still in the basket. Is this common? What would cause this to happen?

I measure the other disks and they measure .150. My shop manual says to replace them if they measure less than .140, so I guess they are alright. The metal disks were glazed and showed signs of burning in spots. I sanded them with 220 grit sandpaper and they look good now.

Is is alright to just replace the one broken friction disk?

Probably an aftermarket clutch. Those old Barnett clutch plates did that all the time. Buy original Kawasaki plates.

Quite common with OEM style aluminum friction plates. That is why high HP KZ dragbikes using oem style plates take the clutch pack out every few runs and replace the broken ones.

Steel type plates like our extra plate kits don't do this.

kzzone.com/clutches.html

"I measure the other disks and they measure .150. My shop manual says to replace them if they measure less than .140, so I guess they are alright."...

If you're that close to tolerance... replace them for they're not that expensive really...

I replaced the OEM steel plates, friction plates and springs for $120... Definitely was worth it...

you can replace just the one....i m with dave though...new stock stuff isnt that expensive and will work fine....new metals, fibers, and stock replacement springs and a new cable....re-adjust and you wont have to mess with it for many, many miles.....

This 1075 build is just about to kill my budget, so I think I'll just replace the one disk for now. I'm not too worried about it since it's so easy to change. If I get a few thousand more miles out of it, then great.

Thanks guys!

Actually .150" is very good. The plates start out at .157 new. You can replace just one plate. That is how Kawasaki sells them anyway. If it is an OLD Barnett "Cork" pad clutch, get rid of it. If it is an OEM clutch, they are quite good. One thing I WOULD change are the springs. They go week with in about 6-6 years. I just had to change the ons in my 81 motor because I checked them on a spring compression gauge and they were WAY under spec even though they were with in spec length wise. Get a set of EBC "326-7912" springs from Z1E they are quite cheep, about $15 or less. Week springs will ware out a clutch quite quickly due to excessive slippage.

just replace it your clutch pack will be fine i break the inside 2 all the time it's mostly caused by hard lanches and hooking up hard i have been using used stock clutch plates for years in fact i have a stack of of around 50 each of the fibers and steels that i carry in my race trailer for just such occasions.used plates or what i call seasoned seem to work the best for me i haven't bought a brand new set of clutch plates in over 20 years. also i dont re surface the fibers but i do beadblaST scotchbrite the steels to get any glaze of them.

Thanks otakar. How can I tell if it's a Barnett Cork? I will go ahead and order new springs.

If you put heavier springs in it, be sure you have the needle bearing pusher.