Rear sprocket mounting tip

Ever notice how your chain tension has "tight" and "loose" spots? Here's a tip that can help minimize this. By design, the rear sprocket is a clearance fit with respect to the register on the rear wheel. In the case of my KZ 1000 LTD, the clearance was just a shade under 0.006". Ideally, you want to have the rear sprocket mounted so that it is concentric with your rear wheel when tightening up the mounting bolts. The trick is to make up some shims to place between the sprocket and rear wheel register to help center the sprocket. In my case, I had some 0.001" stainless shim stock lying around so I doubled up on it. In the past, I've used aluminum soda cans (approx. 0.003" thick) on other bikes. The principle is the same. I've attached some pics. Hope that they make sense.

Mike

Your idea to center the rear sprocket to rear wheel hub provided a precise made rear sproket. Any aftermarket rear sproket i put on my bikes has light press fit. Some hubs are milled with a conical shape to center the sprocket. Never though about truing a rear sprocket and how to verify or measure up it´s centered to the hub.
Only worn chains and sprockets has "tight" and "loose" tension spots.

Thanks Scirocco - very interesting. I've never encountered a rear sprocket/hub combination that was an interference or shrink fit. Do you heat the sprocket slightly before installation to allow you to mount the sprocket and align the bolt holes? I could see where this setup would eliminate any eccentricity of the sprocket.

And, I'm not familiar with the hubs that have a conical mating surface for the sprocket. Again, I can see the value in this. Would you have any pics or a link to this setup. Always interested in learning something new.

Thanks again.

Mike

I have seen rear sprockets chamfered on one side that put on a sprocket hub with an o-ring that do fill the chamfered area. It´s like a press fit self centering feature.
Sorry if got no pics but i would do so next time. I have seen this feature on some French Renauld cars to center the wheels on hubs.

Michael

The OEM KZ650 sprockets are chamfered on one side. Images below show each side of a NOS sprocket. Ed

Pretty much all motorcycle sprocket bores are parallel to their stubs.
Any loose fit is down to the quality and accuracy of the sprocket and any slight taper in the bore is down to the stamping process on cheaper sprockets where the bore isn't finish machined to the correct size.
The chamfer on one side of the sprocket goes toward the wheel and it's to prevent stand off where the sprocket sits in the corner circumference of the wheel stub as this is rarely a tight 90 degree but a slightly rounder profile due to the machining cutting tip profile.
Centering the sprocket on the stub is a good idea but if the sprocket is that loose you can bet the stamping isn't that accurate and the teeth don't run concentric to the center anyway.
The best way to check for runout is to clock the teeth with a dial gauge while rotating the wheel on its spindle but a discrepancy of a couple of thou or so isn't going to make any difference.

Only worn chains and sprockets has "tight" and "loose" tension spots.

The 650-CSR owner's manual says to find the tightest spot in the chain when adjusting the slack, so Kawasaki obviously expects there to be a tight spot in the drive chain. My chain isn't worn or stretched or loose & the sprockets are good, but I try to find the tightest spot when adjusting it. it's a subtle difference where the chain is tightest. The tight spot in a worn or stretched drive chain will probably be obvious.

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martin_csr wrote: Only worn chains and sprockets has "tight" and "loose" tension spots.

The 650-CSR owner's manual says to find the tightest spot in the chain when adjusting the slack, so Kawasaki obviously expects there to be a tight spot in the drive chain. My chain isn't worn or stretched or loose & the sprockets are good, but I try to find the tightest spot when adjusting it. it's a subtle difference where the chain is tightest. The tight spot in a worn or stretched drive chain will probably be obvious.

Chains begin to stretch as soon as they are installed and used; this is expected behavior and the reason manufacturers tell you to check the slack/tension of a new chain after a certain number of miles.

This PDF book goes into a LOT of detail but some of it is pretty interesting.

www.ustsubaki.com/pdf/the-complete-guide.pdf

This a non issue.