TOPIC:

Hi all, I thought I'd give this query its own heading, seeing as it is so important.

My 1979 basket case still had the original cam chain tensioner and I was advised through the forum to upgrade that. Suggestions in the FAQ on the site pointed me to buy the ZX-11 one (Kawasaki Part # 12048-1113). However, there seemed to be a question about having to shorten the spring for the new one, but no real clarity anywhere that I could find.

The question was: can the new one simply be used or does it need the spring shortening to lessen the tension so it is the same as the old one? The thought being that the new one would put too much tension on the chain and wear out the chain rollers(?).

I was thinking of all sorts of clever ways to measure the different tensions, but in the end I simply compared the pressure I needed to used to depress the springs by one finger, and certainly the new one needed a LOT more pressure to depress fully. Therefore the tension will be much more with the new one.

So the questions still stands: Do I need to cut the spring on the new tensioner before I install it? What have other people done?

Pics of my test attached.

Both in the vice:

New one:

Old one:

If you search the forum for cam chain tensioner you’ll find lots of information. Member strate6. - Pete - has used the ZX11 tensioner with , I believe, 10mm cut off the spring, and he has had no issues on his many 1300’s. Yet, the truth is that shortening the spring actually INCREASES the force needed to compress it ! So what effect on the cam chain gear / roller longevity will that have?
There are other options apart from using the ZX11 tensioner, and these have been discussed on the forum. Personally, I intend using the original tensioner, but with a locking bolt, as Lare Numinem suggested.

The modification is to shorten the spring by 10mm.
Simply remove it from the tensioner body and cut 10mm off either end.
Next fit the body (with a new gasket) into the tensioner hole, then insert the spring with the chrome pin inside it and screw the HOLLOW Bolt with the copper washer fitted, into the end of the body and carefully tighten the bolt. Its a bit tricky as you have limited space available.
You will hear the tensioner clicking and pushing against the guide inside the tunnel as you tighten the bolt........thats ok !

I personally would not start any Z1300 engine with the original tensioner fitted, having had 2 fail over the past 40 years and paid the price of new valves, cylinder head etc...etc...etc....its the VERY FIRST MOD I have done on all my Z1300 and KZ1300.
Its a very good, cheap worthwhile modification and once done you can forget it as its all self adjusting.

Another good alternative is the way Jim has mentioned with a Manual Type Mod to the original tensioner or fit an APE Manual Tensioner...........the only slight drawback with that way is having to manually adjust the slack every now and then.

Pete Finn
UK

Many thanks Pete, that is the info I was after.

Best
Paul

I personally have been swayed by new information regarding shortening the ZZR CCT spring & whether it increases tension force, this was posted by Ian on the international Z1300 Facebook page after he carried out tests:
"well WoW the standard cct spring is putting 650 grams of force on the chain at a length of 52 mm
the zzr spring is putting over 1030 grams of force at the same compression with 10mm cut off, that was taken at the end of its travel which is 52mm so if you cam chain isnt that slack then more force will be applied.
compressing the ZZR CCT by 10mm nearly doubled the force applied to 2000 grams.
the standard CCT only went up to 920 grams at 10mm compression.
Phil i would be interested in how much force you will get with a full length spring.
think ill stick with the standard CCT with modified with a back stop."

Lauri Nurminen quoted:
"I use the original tensioner, just change the M6 bolt for one 15mm longer. Every 2000 km or so I loosen the bolt, let the adjuster do its thing and then lock it with the longer bolt. The tensioner can not fail when locked in place. Costs only what longer bolt costs."

Luckily I kept the original CCT when I changed out mine for a ZZR one 20 years ago, I think I'm going to do what Lauri has done

Phil wrote: Lauri Nurminen quoted:
"I use the original tensioner, just change the M6 bolt for one 15mm longer. Every 2000 km or so I loosen the bolt, let the adjuster do its thing and then lock it with the longer bolt. The tensioner can not fail when locked in place. Costs only what longer bolt costs."

Just thinking out loud about this....

The threads in the body of that tension wouldn't take much torq to strip out. This exact thing happens with CB750/900/1100F B chain tensioners which have just such a bolt - kind of painful to fix as the tensioner body is cast as part of the cylinder head.

Made me think: why not drill and tap a hole for a small bolt (and lock-nut) in the end of the tensioner body (axially lined up with the tensioner plunger). Retain all the internal tensioner parts and just lightly snug up the bolt occasionally to take up any slack left by the tensioner adjusting forward. i.e preventing the plunger from moving backwards.