For Sale - 18" Rear Disc Mag Set Up

[nwwa]

Sold.

 

[53xs650]

Do you have a sr500 or a xs500 Wheel?

 

[nwwa]

Everything is off of the same '78 SR500.

I'm going with an aluminum swingarm and spoked wheels on the bike and thus have no need for the rear end.

 

[53xs650]

Just to let You know, If is a SR500 then the cush drive is way too big for a 30-34 tooth sprocket.

 

[nwwa]

Oops, looks like the thread I linked and read isn't quite accurate.

Sounds like Rebel Gears will make a 38t sprocket for the SR500 wheel for about +/- $50

http://www.xs650.com/forum/showthread.php?t=31813&highlight=rebel+gears+sr500

http://www.rebelgears.com/pricelist/rear.html

Running a 38t rear and going up 1 tooth to 18 in the front (18/38) will give you a gear ratio of 2.11 vs the typical XS650 ratio of 2.00 you get with the stock 17/34 gears.

http://www.jtsprockets.com/fileadmin/files/jtgearratio.pdf

So all in all, not much difference, plus you have much better/broader tire choices and significantly improved aesthetics with the 18" rear mag.

Additionally you could further fine tune the gearing by calculating different overall diameters of various tire aspect ratios on the 18" rim.

As mentioned above, I'll get pics posted in the next day or two.

 

[650Skull]

O

Running a 38t rear and going up 1 tooth to 18 in the front (18/38) will give you a gear ratio of 2.11 vs the typical XS650 ratio of 2.00 you get with the stock 17/34 gears.

No......An 18/38 is equivalent to a 17/36, 1 tooth on the front = 2 teeth on the rear

There are variations on tyre sizes but generally the 16" rim and tyre and 18" rim and tyre are about the same circumference. There may be a small reduction relating to sprocket ratio but generally XS650 riders reduce the standard 17/34.

 

[nwwa]

I'm not sure what your post is trying to accomplish xs650skull....

As I mentioned above, with the SR500 wheel and 18/38 gearing the gear ratio is 2.11 (38 ÷ 18 = 2.11)

A stock XS650 gearing of 17/34 gives a gear ratio of 2.00 (34 ÷ 17 = 2.00)

This, as well as every other plausible gear combo, is laid out in the table I linked to above:

http://www.jtsprockets.com/fileadmin/files/jtgearratio.pdf

A stock 16" mag XS650 running a factory spec and very common 130/90-16 Kenda Challenger tire has a diameter of 25.11" and a circumference of 78.88"

A 4.10" x 18" Dunlop K70 tire appropriately sized for the SR500 rear wheel has a diameter 26.73" and a circumference of 83.97"

So despite a gear ratio difference of 5.5% between the 16" XS mag & 17/34(2.00) gearing and the 18" SR Mag & 18/38(2.11) gearing, the overall circumference difference of 6.45% (SR @ 83.97" ÷ XS @ 78.81" = 1.065) between the two, essentially mitigates that difference.

This rear end wont be the ideal fit for every build, but will suite a great many, esp those after a more flat/street tracker look and associated torque oriented performance.

A lot will depend upon the characteristics and tune of your motor, low end vs top end intent, overdrive 5th gear, etc...

 

[nwwa]

Bump