Belt Drives LTD.

BDL Belt Drive Kits

A BDL belt drive replaces a stock primary chain with a toothed belt, cutting down on maintenance and noise while adding a distinct look to the primary side of a Harley Big Twin. Belt Drives LTD (BDL) has built these kits from their own facility for decades, running everything from an aluminum foundry to in-house CNC machining and rubber manufacturing.

Fitment by Year and Start Type

This collection covers Big Twin fitments from 1936 all the way through 2006 FXST and FLST models, split by kick start and electric start configurations. Earlier kick-start-only kits run from 1936 through the mid-1960s, while electric start options begin appearing for 1965 and later models. Belt width and shaft type both vary by year, with 8mm and 11mm belts and tapered or spline shaft options depending on the exact model.

Open vs. Enclosed Primary

Open belt drive kits leave the belt and pulleys visible, a common choice for builders who want the mechanical look on display. Kits are available with or without a cover depending on the model, and finish options include polished and black for the later FXST/FLST kits. An idler gear is built into select 11mm electric start kits for the earlier Big Twin years.

Fitment and Installation

Belt width, shaft type, and start configuration all need to match the exact year and model before ordering, since these components aren't interchangeable across Big Twin generations. Most builders pair a new belt drive with fresh clutch components and primary hardware at the same time, since the primary is already open during install. Check the product listing closely to confirm compatibility before purchasing.