Z650 B1 cam chain idler wheels

Hi Everyone

I'm in the middle of doing a top-end overhaul on my Z650 B1 (which has a roller cam chain, not the later Hyvo type) and have just discovered that the cam chain idler gears are no longer available from Kawasaki (the ones with the metal teeth).

The plastic section in my gears is breaking up.

Does anyone know of any alternative parts that can be used? I know APE do alternative cam chain idler gears for the Z1000, but they don't list them for the 650.

Any ideas please?
Thanks
Lama

I always thought the 650 used the same exact gears as the 900 and 1000, but in looking up the part numbers they are different. If you look up the 650 and use the cross reference fiche from Kawasaki it says the 650 gears were only on the 650, but if you look up the 1000 gears it lists them as being used on the 900-1000 as well as a 1977 KZ650B1. So they may in fact be the same part or at least interchangable.
Good luck. If all else fails they should be plentiful used.

Thanks for the reply Ron,

However, I'm pretty sure that the 900/1000's use a different cam-chain and consequently different cam idler gears. The shafts that they run on have the same part no. as the 650B, as do the rubber damping blacks.

I'm not keen to use second hand ones as they may well also be 30 years old and about ready to start droping chunks of plastic into the oil etc.

I was hoping that someone might be able to advise me wether the later Hyvo type blades could be substituted whilst retaining the earlier type chain.

The part numbers differ for the cylinder head and block, but this might only be due to being painted different colours.

Any thoughts anyone?

I really think the 1000 uses the same chain, just a different length, but I'm not positive. I understand your point on the plastic falling in the oil, and I felt the same way. This was about 1992 when mine went bad and I went to Kawasaki and if memory serves was quoted $72 per wheel x3=$216.00. Expensive stuff when they were available.
lama7 wrote:

Thanks for the reply Ron,

However, I'm pretty sure that the 900/1000's use a different cam-chain and consequently different cam idler gears. The shafts that they run on have the same part no. as the 650B, as do the rubber damping blacks.

I'm not keen to use second hand ones as they may well also be 30 years old and about ready to start droping chunks of plastic into the oil etc.

I was hoping that someone might be able to advise me wether the later Hyvo type blades could be substituted whilst retaining the earlier type chain.

The part numbers differ for the cylinder head and block, but this might only be due to being painted different colours.

Any thoughts anyone?

i wonder if a small run of the rubber wheels could be machined (i know urethane can be machined, can rubber?).

Anyone know the type of material used for these? hardness and whatnot? It would be a fun prospect to run across my tinkering madman machinest friend.

There are only two pieces in the cam chain tensioning stuff that make much sense to "machine out of rubber". The lower roller that sits over the sprocket on the crankshaft as it is there to "cushion" the chain when it slaps. Also the rubber bit that hangs on the front of the cylinder block which is also a cushioning piece. The OTHER rubber bits needed are the dampener fingers under the rollers that cushion the shafts that the rollers sit on and the rubber pads under the upper idler assembly which is also used for dampening. The sprocket rollers themselves are generally made out of steel in aftermarket situations due to durability... no rubber involved like the stock sprockets. You get a little more noise but they don't tend to come apart as do the stock ones when the rubber gets old.

Very interesting thread - Jeff posted a related thread here about cam chain tensioners.

If the idler gear shafts are the same between the 650 and 1000 the only issue would be the cam chain/idler gear pitch and gear width - if the pitch is the same and the gears are app. the same size I can't see why it wouldn't work. I measured a (new) 650 cam chain, goes like this:

- plate to plate - inside: 5 mm
- roller to roller - inside: 3 mm
- pin center to pin center: 8 mm

The 650 idler gears are 44 mm OD, 14 mm wide and have 17 teeth - the shafts are 11 mm OD.

Would be great if someone could measure the 900/1000 chain and gears so we can check if the gears are indeed the same or at least close enough to swap.


lama7 wrote:

I was hoping that someone might be able to advise me wether the later Hyvo type blades could be substituted whilst retaining the earlier type chain.

If you have money to burn anything is possible, but I would say no - if you check the pic below you can see a very important difference: the single roller type has a chain tensioner that pivots around a shaft sitting in a recess in the top of the cylinder block, the hyvo type plastic tensioner pivot shaft sits in a groove in the upper engine case (at the cylinder base) - this groove can not be machined into the old style cases, there is not enough material there to hold the shaft.

Here's a little background on the differences between single roller and multiplate (hyvo) setups - the parts diagram to the left is an 80 650 F1 (last 650 to use the single roller chain), the right one is an 81 650 H1.

The 650s use the same cam chain train (single roller) from the 77 B1/C1 up to and including the 80 F1 (650 Custom) - chain tension adjusters vary slightly between models but are interchangeable.

As you can see below this setup has three cam chain idler gears (or sprockets if you will) - front, rear and top - and the cam chain tensioner is a rubber wheel sitting in a bracket hanging from the shaft where the rear idler sprocket also sits. It also has a rubber roller guide sitting inside the cam chain at the cylinder base.

From the 1981 F2 (starting at engine no. KZ650BE124001) the 650s use the same multiplate (hyvo) cam chain train as the 750 fours - the hyvo setup doesn't have the idler sprockets but uses two plastic guides front and rear and a top damper that sits in the valve cover. The rear guide also serves as cam chain tensioner.

1980 650 E1 (650 Ltd) and 81-83 650 H1-H3 (650 CSR) are US market specials - the E1 uses a single roller cam chain, the H models use a hyvo chain.

The stuff from an earlier Z1/KZ900 and early KZ1000 will work in any later KZ1000 I think but not vise-versa. The idler tower on top is bigger on the later bikes and won't fit under the early valve cover. I THINK that the chain lengths may also be different but I think the chain links and sprocket pitch is the same. Jeff would know I guess and he can look at an early vs late KZ1000 cam chain and tell us plus compare them to the 650 stuff. If someone put together a "kit" complete with all the stuff, I suspect it would be expensive. I couldn't hazard a guess but would think that one of the companies that specialize in KZ stuff would be willing to get "kits" made up IF the demand at the proper price were there...

As far as rubber bits falling apart and falling into your engine, this is a serious problem. In the past few months I have rebuilt a number of engines and have seen the rubber on one of those upper toothed wheels COMPLETELY missing. It must have been some of the glop in the pan and the engine was probably a mite noisey bwhahaha I have also seen that front rubber bumper totally missing except for the two arms and metal part that fit into the slots in the block. No trace of that junk either. I would say that about 90 percent of the front rubber pieces I see are broken. Next time you look at yours, take it out using an impact driver with a long #2 bit and look at it. Look at its back and flex it. You most likely will see a crack. That is the first step to it falling apart, I guess.

I had some KZ650 idler sprockets here a week or two ago, and on the surface they looked identical to the Z1/KZ900 version - 17 tooth.

I'm not sure the shaft size is the same - I measure the stock Z1/KZ900 idler sprocket shaft at 11.1mm not 11mm. I can get some more of the idler sprockets in to check for sure - I should have tried putting them on a Z1/KZ900 shaft to see if they are the same bearing inside.

Jeff, the difference (11 vs 11.1 mm) might be due to my cheap caliper or sloppy measuring - I checked buykawasaki and the shafts have the same partno. (12052-005) for the 650s and the 1000s, at least the 1000 models I checked (78 A1 and 80 A4). Looks like the gears really are interchangeable. I'll see if I can get hold of a 1000 shaft/gear to verify.

Visited a guy I know today to compare the 650 idler gear to the 900/1000 gear.

All the 650s that has a single roller cam chain use three of the same gears (12055-004) - the top gear is removeable from it's bracket.

On all the 900s/1000s up to and including 1980 models the front and rear idler gears are the same (12057-002). There are at least two different top guides used (maybe more) - some of these have removeable gears, some don't. If the top gear is removeable it's the same part no. as the other two (12057-002).

In the pic below you can see a 650 gear (12055-004) and a 900/1000 gear (12057-002) side by side on a 650 shaft (just for good measure I also checked with a 900/1000 shaft) - they are the exact same size, shafts are the exact same size (and same part no, see post above) and the gears both have 17 teeth.

My conclusion: even if the gear part numbers are different between the 650 and the 900/1000 it's the same part that can be swapped directly between pre-1981 650 and 900/1000 engines.

Thanks for your efforts on checking this out.