what is stock teeth size on rear sprocket - how to get stock gearing ratio?

I have a 79 Kz650B. How many teeth are on the stock rear sprocket?

Post edited by: elcid, at: 2008/03/01 13:55

42T

I got some mag wheels from a kz440 or 400. The rear rim is actually smaller - maybe a 16 inch. But the rear sprocket seems bigger as the chain is so tight & the wheel is pushed all the way forward & cannot go any further. Basically I want to match the same gearing as the stock bike. Considering the new wheel is smaller & the new rear sprocket is bigger, what size rear sprocket do I need for a stock gearing ratio? Thanks.

bump

How about getting a longer chain so that the wheel can go back further.

Chain length has nothing to do with gearing. If you have the stock gearing than get a longer chain.

16T front
42T rear

102L chain

Post edited by: love2ride, at: 2008/03/02 20:41

I am not making myself clear.

I have a wheel from a KZ440 on it which is a smaller wheel but has a bigger sprocket (45t). Let's forget the chain for now.

What size rear sprocket (teeth) should I have considering the rear wheel is smaller but with more teeth than a stock kz650 wheel (or is it?) so I can have the same gearing ratio?

Post edited by: elcid, at: 2008/03/02 20:47

www.bikerenews.com/Stories_Archives/GearRpmSpeedCalculator.htm

Thanks for the tip love2ride but I'd rather have a direct answer. Can someone else chime in?

Am thinking the 16 inch rear tire on KZ650LTD and KZ440LTD were same 130/19-16 size with same overall tire diameter as the 18 inch standard models, so 42 tooth rear sprocket would be stock on both KZ650 models. Therefore a 42 tooth rear sprocket should be okay on the 16 inch LTD wheel being transplanted in place of the KZ650 standard 18 inch rear wheel, presuming everything else fits (such as axle size, etc.), and result in the same stock gearing ratios.

If the 16 inch has more than 42 teeth, it may be oem for the different model, or perhaps was changed to a larger size from stock. Notwithstanding, the same stock 42 tooth rear sprocket for the KZ650 would be applicable regardless of whether using an 18 inch or a 16 inch rear wheel.

If a rear sprocket larger than the stock 42 teeth is used, the stock gearing will be changed and result in higher rpm at any given road speed. Going to a larger than stock rear sprocket frequently does require a longer chain to get around the larger sprocket.

Good luck with the modifications!

Damn thanks! That's exactly what I was looking for.

The rear wheel I have is a mag with 45t. This makes the chain too tight but more than that I have very little power when starting out. I have to keep the clutch in forever it seems when starting from dead stop.

So now I need to look for a sprocket that will bolt onto a kz440 mag BUT have 42T.

You know of anywhere? It seems that the websites I checked only have the sprockets in the stock teeth sizes. AFAIK the kz650 sprocket will not bolt right onto the kz440 wheel.

The following link was navigated to from a site reference at Z1Enterprises.com.

Some guesswork involved, but if reading correctly, looks like 440LTD stock rear sprocket was 45 tooth (as currently fitted on the 16 inch wheel at hand).

Several different sizes are listed, including 41 tooth and 43 tooth, but NOT a 42 tooth (groan).

But somewhere out there is probably a 42 tooth rear sprocket for a KZ440LTD 16 inch mag rear wheel.

rear sprockets

This statement is troubling -- The rear wheel I have is a mag with 45t. This makes the chain too tight but more than that I have very little power when starting out. I have to keep the clutch in forever it seems when starting from dead stop. Troubling because the oversize rear sprocket should have the opposite effect. In other words, an oversize rear sprocket should act like the bike is in a lower gear which would feel like more power when starting out with less clutch feathering needed. Am wondering if your bike has the standard FRONT sprocket or if it has in the past been changed to say one tooth larger by someone attempting to lower the rpm at any given road speed.

According to the above posted info from love2ride, the stock front sprocket on your bike is a 16 tooth. It would probably be a good idea to check the front sprocket and count the teeth to be certain of the actual size and whether it's the stock 16 tooth size.

Good Luck!

This statement is troubling -- The rear wheel I have is a mag with 45t. This makes the chain too tight but more than that I have very little power when starting out. I have to keep the clutch in forever it seems when starting from dead stop.

Yeah, no kidding, the only possible reason that I can think of is that the chain is to tight, as in "extremely". Otherwise it should be easier to take off from a dead stop, but would have a reduced top speed and higher cruising rpm at the same mph.

Is the bike hard to push in neutral??

If you check the tire manufacturers websites, most of them list the diameter for the various sizes, it seems like the 130/90/16 averages about .375" shorter than the 120/90/18. Not a whole lot of difference.

Post edited by: steell, at: 2008/03/03 09:43