Kawasaki Z1/Z900 top cam roller DIY repair guide

[Gray17]

Hi Guys, well if youve read any of my posts you will know im on with a full on resto of my A4.
I stripped the engine fully to allow vapour blasting and am now chcking everything before the rebuild. One job I've found that i wasnt expecting was the cam chain roller replacement, nor was i expecting the 3xtortionate prices of the replacement parts
After examining my own parts i found that the rollers with the teeth break because the centre rubber material breaks up leaving them loise and rattling around as all but 1 are of this design i decided to see if you can repair them yourself using standard DIY tools.
Ok take the top roller which is very expensive. You have a metal bracket bent in a U shape between which is a roller with teeth, the roller utilises a needle bearing and steel shaft to rotate, between the needle bearing and out metal tooth rim there is a gap taken up with rubber type material, it is this that goes brittle and disintegrates, parts of which go into your engine not good.
So to the repair.
1st i drilled out the central pivot rivet with a 3mm cobalt drill. Then enlarged this using a 8mm to the rivet head depth only. You can then tap the pivot retaiter shaft out., next spread the U shape bracket slightly to release the pivot shaft from its location. The roller assembly will drop out. If like mine the rubber centre is missing the cog is very loose on its shaft. I decided at this point theres got to be a cheaper alternative.
The solution
I seperated all of the roller cogs parts, gave them a good clean then
Next i took the central rivet i had drilled out and tapped it all the way down to 5mm, without going all the way through ( i reasoned the hole may be a specific size for oil entry) i then found a M5 hardened screw and shake proof washer to allow the unit to be replaced later. Make sure the screw doesn't go as far as the oil gallery hole in depth.
Now to the roller i found that using a piece of metal tube cut to the same thickness as the needle bearing and outer cog bearing it takes up the space from the missing rubber material. It becomes a metal sleeve.
I then peened the new sleeve on both sides to lock into place using a centre pop. (see photo) i then re assembled everything in the reverse order. The central pivot has 2 keyways at each side which must engage in the U brackets cut outs, this stops the shaft rotating.
Next insert the freshly drilled rivot rhrough the pivot and engage the flat at 1 side, next apply locktite to the thread then the shake proof washer and tightened it.
Now if all correct the cog should have virtually no play and spin freely and should be virtually indistinguishable from the original apart from it can now be repaired in the future if needed.
As the most of the other rollers are similar design you could repair the others in a similar way thereby eliminating a design issue and hopefully improving longevity.
Of course what i dont know as yet is will the cam chain assembly be noisier with metal rather then the rubber material, that i cant say as yet, but i will be the guinea pig to see.
Couple of points to note
1. Before attempting this mod first make sure the needle roller bearing is in good condition and rotates freely with no noise.
2. Check that the bonding on the top toothed cog is sound and that there's no damage to the teeth of the cog.
If either present do not attempt repair, buy new!

[zed1015]

No offence intended but from a mechanical and visual standpoint that looks fairly horrific and i'm not sure if this is a joke post but i've made tons of these and unless that metal "sleeve" is a tight press fit with no peening needed in an attempt to secure it and no runout i advise against using it .

This version retains the original inner steel bearing sleeve.

PICT1475.jpg (119.35 KiB) Viewed 5420 times

And the latest just the sprocket ring on all billet alloy centers.

PICT0065%20(2).JPG (191.34 KiB) Viewed 5420 times

Neither are any noisier that stock which yours may be if it destroys itself

[Gray17]

Hi yes the differences between yours and my solutions are the same as chalk and cheese.
Yours is a well engineered solution that will probably outlast the machine, probably designed with racing or dragging in mind where the engines are run at max on a daily basis and will easily stand these stresses.
Mine is merely a repair of an existing design, which to be fair has lasted for nearly 50 years before breaking up. The sleeve was indeed a snug fit and was made from steel seamless tube, stainless may be better but didnt have any handy. there is no appreciable run out i can detect or vibration and it has been bench run at high speed using an airline to test. Aesthetically its burried in an engine and cant be seen and looks virtually identical to original. So personally dont see that as an issue. But agree yours look far better.
My idea merely takes Kawasakis initial 95% design and replaces the 5% hard rubber centre with a metal replacement that wont break up. The peening was done to ensure the sleeve didnt move, probably not needed as it was a tight fit, also its encased in the U bracket so cannot move far. Mine will never replace yours or the originals, its merely a cost effective alternative.
From my prospective if money was no object then obviously you'd buy the better engineered solution, but in some cases the parts prices have become ludicrously expensive and far outweigh the engineering and material thats gone into them. Supply, demand and in some cases purely greed. £500 for a camchain kit, £4 for a rubber block which probably costs pence to make.
Yes i know thats why the bikes now command such high prices and as a collector thats great. But for someone who just wants to ride it, its not Why?
Well for a start youre worried everytime you go out, you may fall off or damage it, or if you leave it someone steals it, or it gets wet and deteriorates, worst its stuck in the back of a garage because you cant afford the parts prices to keep it on the road. Sacrilidge.
I therefore truly believe there is a place for all solutions if they work in the same way a car gets you from A to B but some do it in style whilst others just get you there!
My idea of sharing any ideas and let everyone make their own mind up

[rpeters]

Bravo Sir!.....but I think I would get one off Rob

[deka]

Hi yes the differences between yours and my solutions are the same as chalk and cheese.
Yours is a well engineered solution that will probably outlast the machine, probably designed with racing or dragging in mind where the engines are run at max on a daily basis and will easily stand these stresses.
Mine is merely a repair of an existing design, which to be fair has lasted for nearly 50 years before breaking up. The sleeve was indeed a snug fit and was made from steel seamless tube, stainless may be better but didnt have any handy. there is no apprecable run out i can detect or vibration and it has been bench run at high speed using an airline to test.
My idea merely takes Kawasakis initial 95% design and replaces the 5% hard rubber centre with a metal replacement that wont break up. The peening was done to ensure the sleeve didnt move, probably not needed as it was a tight fit, also its encased in the U bracket so cannot move far. Mine will never replace yours or the originals, its merely a cost effective alternative.
From my prospective if money was no object then obviously you'd buy the better engineered solution, but in some cases the parts prices of parts have become ludicrously expensive and far outweigh the engineering and material that gone into them. Supply, demand and in some cases purely greed. £500 for a camchain kit, £4 for a rubber block which probably costs pence to make.
Yes i know thats why the bikes now command such high prices and as a collector thats great. But for someone who just wants to ride it, its not Why?
Well for a start youre worried everytime you go out, you may fall off or damage it, of if you leave it someone steals it, or it gets wet and deteriorates, worst its stuck in the back of a garage because you cant afford the parts prices to keep it on the road. Sacrilidge.
I therefore truly believe there is a place for all solutions if they work in the same way a car gets you from A to B but some do it in style whilst others just get you there!
My idea of sharing any ideas and let everyone make their own mind up

well done i admire your thought process

[Z1streetfighter71]

No offence intended but from a mechanical and visual standpoint that looks fairly horrific and i'm not sure if this is a joke post but i've made tons of these and unless that metal "sleeve" is a tight press fit with no peening needed in an attempt to secure it and no runout i advise against using it .

This version retains the original inner steel bearing sleeve.
PICT1475.jpg

And the latest just the sprocket ring on all billet alloy centers.
PICT0065%20(2).JPG
Neither are any noisier that stock which yours may be if it destroys itself

Where do you sell these from mate?

[zed1015]

Where do you sell these from mate?

I haven't got them for sale.
I made enough for my own engines i'm building .
Making them for myself is obviously a lot cheaper in materials than buying APE or Liska etc but for the time it takes on a manual lathe there wouldn't be much in it trying to undercut the mass produced stuff.

[Z1streetfighter71]

Where do you sell these from mate?

I haven't got them for sale.
I made enough for my own engines i'm building .
Making them for myself is obviously a lot cheaper in materials than buying APE or Liska etc but for the time it takes on a manual lathe there wouldn't be much in it trying to undercut the mass produced stuff.

Ahh man so you’re setting me off on a new project when I get back along with boring out carbs to 29mm (was in the middle of making my jigs) I have about 8 junkers so it looks like I’ll be following your lead, did you fab a jig to hold the teeth in you lathe chuck? Or are they completely made from scratch?

[kev edwards]

I would be afraid to put that back in my bike, praise given for incentive though, done my own like Rob.

[Mick J]

It is commendable, making your own improvements and saving money at the same time. I too have done the billet ali centres, much like Rob's original ones (I seem to crib a lot of his ideas!) . The point I wanted to make is, in your second post, you say you spun it up with an airline to test it. I would urge you to replace the bearing, they are only a couple of quid online and if it's been at high speed with no lubrication, it will be toast. Also, don't forget the other two idler rollers that have the same rubber bonded element, they will break up just the same. Cheers, Mick

[Gray17]

Hi Mick, thanks for info have replaced all 3 centres same way, i didnt run up roller without oil, i soaked it before running it ip to speed and then only for a few seconds to check for noise and any vibration.
If i could make the centres like you guys i would but very few people have the necessary skill, Lathe or billets necessary to do so.
My idea is not to take the place of them, merely a cheaper alternative to whats out there. Whilst it may not look as aesthetically pleasing, it doesn't need to as its burried inside an engine. it is however fully functional, after all sleeves have been around in the engineering industry for donkeys years, peening too. This sleeve merely takes the place of the damaged part, leaving the remainder of the original intact.
I believe the unit will function perfectly in practice so much so that im installing it in my own rebuild, why shouldnt it all i've done is replace the part thats failed, with something that shouldn't.
Anyway time will tell.

[Mick J]

All good then

[Gray17]

Thanks Mick, incidentally i did look for new roller bearings just in case. However i measured the shaft as 11mm therefore int diameter should be the same no one seems to do them you can get 10mm or 12mm but not 11mm have phoned up 3 local bearing places they all say the same which is strange where do you get yours from? They are 14mm wide, the outside size depends whether you go to the start of black plastic part or all the way to the cog part? There is no numbers or wording stamped on the bearing either
Thanks

[zed1015]

I measured the shaft as 11mm therefore int diameter should be the same no one seems to do them
Thanks

The bearings they used are not metric but imperial.
They are 7 /16" id (11.113mm ) x 5/8" od (15.875mm) x 1/2" w (12.7mm )
Here's a link to some on ebay.
https://www.ebay.co.uk/itm/273088939663

[Gray17]

Thank you for the info, i mistakenly thought all japanese parts were metric even back in the 70s, also explains why i was getting 11. Something on my digital callipers. I was assuming it was reading incorrectly, it also explains why nobody could supply in the sizes i was asking for. Never entered my head they could be imperial.
I've found a really good price at simply bearings IKO same spec just under £10 for 3 delivered. Thinking i will replace them all as they have served for 40+ years, for that price be silly not to!
Many thanks