The All-Balls-Racing kits from Z1Enterprises.com include the oil seals which is kind of handy. I probably wouldn't have serviced the speedo drive gearbox if not for that seal being in the kit. cleaning & lubing the speedo drive was easy.
I had some lateral movement in my back wheel and discovered that the swing arm pivot bolt was way too loose.
If you can spin the nut on your pivot bolt easily it is too loose, tighten it down to 22-28 foot pounds.
I tightened mine down to 25 ft lb's and have no more lateral movement ( do not over tighten)
