Increase the overall power of your Indian Motorcycle with our 121″ big bore kit, designed from high quality ductile iron sleeves and lightweight forged pistons to give the best overall power and reliability.
In order to perform a 121″ B.B.K. for your Indian Motorcycle, we will need to have your cylinders sent to us. We will utilize your existing cylinders, and with our exclusive techniques, machine them out and install a set of Ductile Iron sleeves, torque plate and fixture hone them to each individual piston’s specs ensuring every piston to bore has the same clearancing specs. We then machine the tops of the cylinders and finish off the surface with a 400 grit lapping to make the best possible seal available.
Our piston design has many years of Research & Development involved to yield the best possible performance and reliability. Our 121″ kit is comprised of a 105.28mm bore with 2 lightweight forged pistons (complete with Rings, C-Clips and Wrist Pins), 2 Head Gaskets, and 2 Base Gaskets. If combined with our Supercharger Kit for Indian models, dished pistons can be provided (kit includes flat-top pistons by default).
In order to install a 121″ B.B.K. some items will need to be addressed:
- Case Boring – Proper clearancing of the cases is required. The bottom approx. 1/2″ of material needs to be case bored in order for the cylinders to drop in.
- It is HIGHLY recommended that after market rods (like the Carrillo custom rods that we use – $880 retail) be used as well, along with balancing the crankshaft
- The use of heavier clutch springs is required, such as the kit available through Barnett.
- Head work is not mandatory, but highly recommended for those using the largest of cam profiles and wanting to maximize HP levels.
- Proper tuning is an absolute necessity after the installation of this build.
- High Flow Intakes and exhaust are required for optimal performance.
When in doubt, please call us directly at 845-744-4889 and we will answer any of your concerns!
An Indian Thunderstroke motor equipped with 121″ Big Bore Kit, combined with our 585 cam profile, can yield approx 120 hp and 148 ft-lbs torque. Results will vary depending on Intake and Exhaust selection.
Please see our Dyno Graphs for additional horsepower comparisons as we test more combinations.