Modifying a KZ650 rear end

Mike,

I'll be following your build thread closely- you've got some great pictures on there

Does anyone know if I can get away with a 530 conversion without too many clearance issues, or do I have to run a 520?

I have a nice Vortec aftermarket 530 rear sprocket for the bike, so I would like to use this if possible.

Thanks!

650mod wrote: Does anyone know if I can get away with a 530 conversion without too many clearance issues, or do I have to run a 520?

I have a nice Vortec aftermarket 530 rear sprocket for the bike, so I would like to use this if possible.

Thanks!

Compared to a 530, a 520 affords an additional 1/16" clearance, when comparing the same style chain, such as o'ring to o'ring or non-o'ring to non-o'ring.

Would be interesting to know overall width of non-o'ring 530 compared to o'ring 520.

Good Fortune!

Patton:

Thanks for the help! One question though- can a 530 sprocket take a 520 chain? Or do I have to modify the sprocket?

Thanks!

650mod wrote: ...can a 530 sprocket take a 520 chain? Or do I have to modify the sprocket?

Thanks!

Because the 520 roller width is narrower than the 530 roller width, the 520 chain (being designed for a 520 sprocket) likely won't fit onto the thicker 530 sprocket.

A 530 chain will fit (with some lateral slop) onto a 520 sprocket.

The 530 and 630 chains are about the same width., because the rollers are the same width (being 3/8").

The 520 roller width is 1/4".

Is it for sure that the 530 is too wide, and that the additional 1/16" clearance of a 520 will afford sufficient clearance?

Good Fortune!

I haven't started my build yet, I'm just trying to get an idea of what I might have to do when I get there. I think I might try to use a 530 on the bike as I don't want to get rid of the nice drive sprocket I have.

So I've started looking at gearing that I'll need to do with the bike as I'm switching over to a 530 chain. The new rear sprocket is a 41 tooth 530 chain, while stock is a 42 tooth 630. I looked over a post on here about chain conversions, and how to roughly calculate the needed tooth # for 530 sprockets, and here's what I get when I input my data (based on taking #630 teeth and multiplying by 6, dividing by 5):

Front
42x6/5= 50

Rear
16x6/5= 19.2

From what I understand, this would be the new sprocket size that I would need to use to keep my gear ratio identical to stock when I switch to a 530, right? The old ratio is 2.62:1, or .3809

Now when I run #'s from a 530 chain to a 630, I take the # of 530 teeth, multiply by 5, divide by 6. Here's what I get if I use a 16 tooth front with a 41 tooth rear:

Front
16x5/6= 13.33

Rear
41x5/6= 34.1

When I run these new #'s to give me a ratio, I get 2.55:1 or .390.

My understanding here is that if I drop my gear ratio, torque goes up, which will help my acceleration. Or do I have the ratio understanding wrong?

Any help is appreciated

The rear sprocket is on the rear wheel, which is the larger sprocket, sometimes known as the "drive" sprocket.

The front sprocket is located under the sprocket cover at the transmission output, which is the smaller sprocket, sometimes known as the "counter-shaft" sprocket.

Using sprockets with the same diameters as the existing sprockets will keep the same gearing regardless of the number of teeth involved.

Typically, many different size diameter rear sprockets are available; but only a few different size diameter front sprockets are available.

Often, the space available for the front sprocket will accommodate only a slightly larger diameter front sprocket.

A slightly smaller diameter front sprocket may fit and serve okay, but a too small diameter front sprocket may reduce chain life.

If one tooth (or possibly two teeth) added or subtracted from the front sprocket doesn't produce the desired gearing, further gearing change may be accomplished by a different diameter rear sprocket.

I suspect the 41 tooth 530 chain sprocket diameter is considerably less diameter than the stock 42 tooth 630 chain sprocket diameter.
And thinking there may not be available a 530 front sprocket small enough to provide the same gearing ratio with the new 530 rear sprocket as is currently provided with the stock 630 sprockets.

Good Fortune!

I understand the difference in chain and sprocket sizes, but I was just wondering if a drop in gear ratio when I change over to the 530 will make a large difference.

My ratio changes from 2.62:1 (old) to 2.55:1 (new). Does this mean I save fuel at top speeds due to having a lower gear ratio? Will I gain torque? This is what I'm after.

Thanks

The stock counter-shaft sprocket on Z1 and KZ900 has 15 teeth.

I've run a 14 tooth counter-shaft sprocket, which resulted in faster acceleration and higher cruising rpm.
And have also run a 16 tooth counter-shaft sprocket, which resulted in slower acceleration and lower cruising rpm.

Wound up being happiest overall with the stock gearing.

Measured difference in fuel mileage was negligible, regardless of 14, 15 or 16 teeth c-s sprocket.

Good Fortune!

Thanks, Patton! Makes a bit more sense now

Hey guys,

Does anyone have any input on shaving the rear cush drive when I go to mount my rear wheel up? Am I shaving the rubber cush down, or am I shaving the cush holder?

Thanks.