How to figure proper amount of offset on sprockets

I got my bike mocked up to check everything over.I measured for my front offset sprocket. The sprocket appears to be really close to straight when the outside of the sprocket is flush with the end of the shaft right where it turns to threads. So i measured the length of the shaft which was right around a inch. Then i subtracted the width of a stock sprocket. This gave me the distance i needed which i believe it means i will need a 3/8 offset. Does this sound correct?

Yup... 3/8 -> 1/2" is ~ correct in most configurations. For my 180 tire, 1/2"/12mm worked just right in my swing arm/sprocket combination.

@ 5/8ths, chain contacts frame tubing.

Comes in 630 or 530 sizes...

Ok. You are using a 5.5in rim ? (the widest possible with the wheel true central)
You need a 5/8 offset front, 530 pitch is best for max clearance to frame/tyre etc..
Measurement from centerline of chassis/swingarm spindle to the back/inside face of 5/8 front sprocket is 101mm.
This is the distance needed for the rear sprocket carrier face to wheel center measurement which on average means approx 8mm machining off the rear carrier to align the sprockets.

I am not sure how wide the rim is? Its a 99-07 hayabusa rear. Iam sorry iam kinda confused on what your saying zed1015. I just had it all mocked up and centered the tire as close as possible. With that being done i stuck the bottom end in the frame and lined the sprockets by sliding the stock front sprocket out until it was straight. Then measured the gap. did i mess it up? Just wanna make sure because i wanna order new sprocket today but wanna make sure i get the right one. Thanks for everyones assistance.

The Busa rim is 6" wide where the tire seats. I'm mounting one in my Gsxr1100 arm on my 900. I did a quick mock up and I'm definitely going to have to turn down the rear sprocket carrier even with a 5/8" offset front sprocket.

Later, Doug

mine measured the same went with 1/2" reallly dont know if 13mm would have been any difference 190 shinko is as wide as possible rubs the chain occaisionally just in the turns I'm guessing

It is impossible to get a 6in rim or 190 tyre in a std Kz1000 frame with the wheel true central.
To clear a 6in rim or 190 tyre you need a 3/4in offset and notch the frame tubes .
With a 5.5in rim and 180 tyre a 530 chain will clear the tyre by 2 to 3 mm and a 630 will slip past by a hair.
The same applies at the frame tube near the pivot area also.
If you have a 6in rim or 190 tyre and have chain clearance too then your wheel is not central in the frame.
The swingarm runs central in the frame and its pivot width is 235mm.
117.5mm in from the frame pivot boss is the frame centerline and the point from which to base all your figures on.

You can not just guess or wing it... You need to take accurate measurements...

First the rear wheel must be centered on the bike... Changing the swing arm complicates things... You can not just eye ball it...

From there you measure the distance from the center of the wheel to rear sprocket mounting surface... You compare this number to the OEM rear wheel distance from the center of the wheel to rear sprocket mounting surface...

The difference is the amount of offset you need...

You can move the rear sprocket in towards the center of the wheel a little... You can machine the hub/sprocket carrier spacer a couple millimeters... You can also remove the studs and machine the hub/sprocket carrier a couple millimeters... The limit is when the tire rubs on the chain... (On the 2006-09 GSXR 600/750 the limit is 5 millimeters.)

From there the counter shaft sprocket can be offset out...

If it comes to close to the frame, I think bracing outside of the frame and trimming the inside of the frame, is a better option than offsetting the center of the rear wheel just to make it work...

Right? Luis

Old Man Rock wrote:
Comes in 630 or 530 sizes...

I wonder if anyone can make these in 525 or 520... Thinner chain = more room... They can handle the power...

If you want to know the correct,accurate way to center a rear wheel i can copy and paste my method from the Oldskool performance site,

Here...
You need the wheel central before you can align sprockets and as said earlier 5.5in rim + 180 tyre is the widest you can run with everything true.

Find true center line of the chassis and mark this on swingarm pivot ( laydown a strip of masking tape on the pivot to mark on)
Easy to do on zed as the frame is symetrical.
Example - z9/1000 pivot is 235mm so center is 117.5 mm.
Bolt in the bare wheel (no tyre) with one solid wheel spacer on sprocket carrier side and whatever spacers/washers you need on the disc side to make up the slack.
Nip up the wheel spindle with the wheel fully forward in the adjuster slots.
Drop a straight edge ( long spirit level) from either side of the rim onto the pivot and mark it.
The distance between these two marks should end up the same width as the rim.
Now measure from each outer (rim) mark to your original centerline marking.
Unless you are very lucky the two measurements will be different.

Take the smaller measurement away from the largest and divide the difference in half and that is how much off center your wheel is.
You will then need to add or remove that amount from the sprocket side spacer to get the wheel central ( if the smaller figure was on the sprocket side then you need a wider spacer and vise/versa )
Once done you just need to make up the correct size spacer/s for the caliper side .

Powerstroke, is this on your '77? If so, I have both 3/8" and 5/8" front sprockets I can send to you for mock up if you want. I am trying to sell them, but in the mean time, you can use them to verify your setup. Send me a PM with your addy. For the record, I have a 5.5" rim with 180 rear tire. I am using a 5/8" offset sprocket and cut down my rear carrier .210" in order to get the correct alingement for the chain. Chain clears both frame and tire. About a little less than .125" on either side of chain. I am using the ZRX 1200 rear swing arm which does have some wheel offset (around .5") in it from Kawasaki. My rear wheel is offset about .25" in the chassis IIRC.

Cory

Its on my 80 1000 but there the same. And as far as the wheel being centered i am not to worried about it being right on the spot. I currently have a 190 on there now and by the way it was set up it appeared i would have to squeeze the frame together some on the pivot area, but i should be able to fit a 200 rear. By the way its a custom swingarm made by les holt.