To change gearing to a taller ratio and eliminate the chance of shredding the stock drive belt, I swapped over to a chain final drive. It’s a straight forward swap. PBI makes both 520 and 530 front sprockets for 5-speed Sportsters that slip right on. Vortex Racing and PMP Sprockets, along with a few other companies, make rear sprockets, and a couple companies make Buell XB specific adjustable idler sprocket arms that replace the factory belt idler arm. Most of them are nice quality but they cost big bucks.
My current chain setup includes a 20 tooth PBI 277 front sprocket, a 45 tooth custom PMP black aluminum rear sprocket and custom cush drive setup, and a DID nickel plated 530 ZVM-X chain.
First cush drive install colors: Gold wheels and chain
This is the original chain drive setup with PMP XB sprocket.
The PBI Sportster front sprockets require a spacer between the sprocket and sprocket nut. Buell Racing/EBR offered a chain drive nut which has a counterbore to clear some of the spline width, shown on left – stock on right:
I went with a 530 chain since I knew I would be pumping some power through it. I also bought the chain guard from the Buell XBRR, part number K0200.07AH, which bolts right up to the newer styled swingarms.
I decided to modify my stock idler arm assembly to allow for adjustment and change out the stock idler wheel for a idler sprocket. It totaled near $40 and works great. I originally used a 15 tooth steel sprocket, which worked fine but was a bit noisy. I later found a 15T plastic idler sprocket from Grainger.com that runs really quietly and is much lighter than the steel one but it will only work for a 530 chain. I now use a custom 17T idler sprocket with an aluminum hub and steel teeth I machined.
Cush drive design is finished. This design uses a modified 2010 Buell XB 3 bearing rear wheel (machined to remove the outer drive-side bearing), a cush bushing adapter plate, a sprocket carrier, and two bearing sleeves that assemble to use 6 OEM Ducati cush bushings with a custom 530 sprocket. The sprocket carrier is supported by two 6908-2RS bearings and the sprocket is centered on the two bearings. The 6908 bearing spacers slip on the stock axle and ensure proper spacing of the assembly. The sprocket center is only shifted by 0.080″ away from the “stock” sprocket center (530 chain drive). The 2010 wheel uses 6206-2RS bearings which have a greater load carrying capacity than the old 6006-2RS bearings.