Replace cam chain or not?

Hi all,
Long time lurker ....small number poster. I have a 1982 KZ750LTD with a little over 19k miles on it. I bought it not running. When I pulled it apart I found a bent exhaust valve and 2 stuck tappets(buckets). I will check all the valves when my new valve compressor tool arrives. Should I consider replacing the cam chain while I have it apart? How long do the cam chains typically last? From what I can tell the auto tensioner still has almost 1/2" of adjustment left. Thank you for your input.

Cam chain should last a long time. No need to replace at that mileage. I'm not sure if your bike is hyvo or conventional chain. I have little experience with the hyvos, but conventionals will go 100,000+ miles.

We could debate the mileage both a conventional or hyvo chain can go before you see signs of stretching but I sure know that almost none of the bikes that comes through my shop has a reliable mileage on its odometer. Most mileages are pretty low considering the age and I wonder how many have been recorded on mileage roll-backs and busted speedo cables? If I were taking off the cylinder head, I would put in new cam chain tensioning bits... the arms and the chain. I like to use a "master link" type chain when not wanting to take the time (or buy a complete gasket set) required for splitting the cases. The hyvo chain comes in a master link variety and since the chain has little side stress, the master link is pretty secure. I have about 15K miles on a conventional master linked chain on one of my carb testing bikes and it seems perfectly fine. When you buy a conventional chain from z1enterprises, they sell two varieties... Jeff claims the cheapo chain should get 30-40K miles and I use those as I doubt I will go much farther between top end rebuilds anyway. The more expensive and durable chain ain't that much more... Jeff can jump in and correct me if I am wrong about what he told me regarding the less expensive chains... my memory isn't what it used to be.

Thanks for the input guys. I only have one more problem. She is 5'7" with brown eyes and red hair. She goes off everytime a new ups or FedEX box appears on the front porch with motorcycle parts in it. I would really like to go ahead and buy the cam chain and breaker/riveter kit from Z1 enterprises but I don't think I can swing another $150 out of the checking account without a realy good excuse.
As for the mileage I am pretty sure it is accurate. I will post some pics later today or tonight.I also noticed a lot of really light flaky carbon on the pistons. Is that normal?

The breaker tool isn't really necessary as you can cut the chain with a die grinder or dremmel tool. You then connect the old chain with the new chain with the master link and pull it through. The fancy tool doesn't help you secure the master link on the new chain anyway. The carbon on the piston crowns is fairly normal.

wiredgeorge

I think I can get her to go for the chain. It is one of the HYVO chains I believe. It doesn't look like a typical chain to me. I noticed the tool at Z1 said it was a riveter also. So, I assume I rivet this chain together instead of master link it? Sorry for so many questions.

I thought it was a master link but check with them to be sure.

Thanks

my observation of many different Z1 / KZ900 / KZ1000 engines is the cam chains have an effective life of about 35,000-40,000 miles. That doesn't mean they with fall apart, but the wear on the chain causes the cams to be well out of time with the crank - many degrees casuing the bike to run lethargic - and yes, the cam chain tensioner can reach it's limit - at which point you will need to invest in ear plugs to keep the engine clatter to a minimum....

I've seem bikes with 70,000 miles on the still running the original cam chain - the flip side is I've also seen bikes where the tensioner was fully extended an the engine was still fairly young.

Jeff,
Does the hyvo chain need to be riveted or does it use a master link. If it is something I can do without buying a special tool then I will need a cam chain for my 82 KZ750LTD.

The master link is a rivet style link - you have to press the sideplate on and peen the ends of the pin over to ensure the plate stays in place.

The chain for your bike is not a Hyvo style chain (assuming we are talking about the 4-cylinder KZ750). It uses an 82RH2015 chain - 150 link.

I'm a little confused, the cam chain for the 750 fours is not a standard roller chain, it's a link plate chain (as shown in the pic at Z1 Enterprises) and link plate chains are what I have always called HyVo chains.

So, what is the difference between a link plate chain and a HyVo type chain?