Primary Chain. Replace or reuse???

I measured the slack to be 17mm. The book says the service limit is 27mm. would you spend the $200 and replace it, or just reuse the chain and deal with the klankety klank noise at low idle? Anybody know what kind of play you get with a brand new chain?

[img size=(01-499)] www.bizfound.com/lebaron/kz750_01.jpg [/img]

[img size=(01-499)] www.bizfound.com/lebaron/kz750_02.jpg [/img]

some of that clankity clank might just be caused by your carbs being out of sync. as far as the primary chain goes you have 10 mm before your at the service limit the chain has lasted this long i might try to reuse it myself but that is a decision you will have to make you know how much work it was to remove and tear down the engine so is it worth all that work again if it doesn't work. plus the gasket set you would use up. your call.

Oh yeah, and even greater news! During dissasembly, I discovered the secondary shaft nut to be loose. Like, as in, just floating around on the threads, not even finger tight!!!!! Super!

[img size=(01-499)] www.bizfound.com/lebaron/kz750_03.jpg [/img]

bring on the red loctite, maybe that might have caused some of your noises good thing you took it apart.

I agree that I've got multiple issues here that could have attributed to the noises. Like you said, carb adjustment definately needs to be done. Also, I had a blown head gasket that was the major reason for me tearing the bike down. I'm leaning more towards keeping the chain as you suggest, I just don't see this massive chain breaking on me any time soon. From what I gather from other posts, the primary chain is notorious for making noise, but it doesn't really hurt anything as long as it's within service limits. I'm not looking to do a show bike rebuild, just would like to get it going again and clean it up a little. I'm just really curious as to what kind of slack a new chain would have, considering that there's no way to adjust the tension.

If you use the red #222 loctite, make sure the area is free of oil and grease. Some brake cleaner with a spray straw and paper towels to catch the excess will work well.

If you don't know, to remove the red loctite the item has to be heated to about 400 F so it should keep that nut tight.

My vote is re-use the chain, these motors are noisy by todays standards. Carb sync and ignition timing have a good effect on rattles and clanks, the timming chain is often the most common culprit of odd noises. That Hy-Vo primary chain is so oversized for these engines that it is very rare to hear of a failure. How are you measuing the chain? Also keep in mind the "service interval" is the most allowable play that the manufacturer is comfotable with re-assembling an engine with, not the point in which the chain is "worn out".


I just re-assembled the case on my 650, the play was between .625" - .750" on mine which is in the ballpark of 17mm I have no reserves at all about puting it back together. The engine had 30k on it.

Just my 2 cents anyways...