There are very few modifications you can perform on an engine that will improve power and torque right through the rev range, but TTP's 904s big bore kit is one of those modifications. Increasing cubic capacity and compression ratio give improved performance from idle to the rev limit, with no downside.
In use the extra top end horsepower is excellent for acceleration and top speed, but the revelation is the extra torque through out the rev range. It makes riding a Triumph twin far more exiting as when you open the throttle, the engine just pulls and pulls to the red line.
Designed by TTP, the 904s kit includes race quality pistons, a custom 904 MLS steel head gasket together with OEM cylinders which are bored, Nikasil plated and then powder coated externally to give a virtually new set of barrels.
**790/865 CYLINDER CORE EXCHANGE REQUIRED BEFORE SHIPPING**
Core must have no broken fins and no scratches on the bore or mating surfaces.
Shipping details will be on your emailed order receipt.
- 12:1 compression ratio.
- Larger valve pockets for +2mm valves.
- Tight quench to improve tubulence & combustion burn.
- Anti-friction coating on the piston skirts.
- Pistons hand balanced to within 0.1gms of each other.
- Nikasil plated barrels give tighter cylinder/piston clearance.
- Hand gapped piston rings.
- Custom 904 MLS steel head gasket.
- Optional OEM gasket kit.
Available for the air cooled Bonneville, Thruxton, Scrambler, America
and Speedmaster from 2001-2016.