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Triples Rule Cylinder Block for Triumph Trident & BSA Rocket 3 MotorcyclesWhy a TriplesRule 855 kit?
--- The Triple should have been an 850 from the beginning. As a 750 it is a revvy solo bike, lots of fun on the open road with just the rider. Add a passenger, luggage or ride on city streets and the engine isn’t that happy, requires lots of gear changes and gets poor fuel economy.

With a TriplesRule 855 kit the engine will pull authoritatively from lower rpms, handle two-up riding without straining and have long “legs”: accelerating smoothly from low speeds to cruising speeds without a lot of banging on the gear change lever. Because you don’t have to rev it to get power the fuel consumption will improve as well. And, if you do wind it up it will blow a 750 away.

---the stock cylinder block is diecast aluminum with relatively thin walls around the bores. The casting alloy for diecast flows easily so it can be injected into the die but doesn’t have the tensile strength and stability that sandcasting alloy 356 aluminum has. The bores tend to distort when hot. This is why triples consume oil at a sometimes alarming rate.

The TriplesRule block is made of sandcast A356 aluminum with thicker walls around the bores. This makes the structure around the bores stronger and more resistant to distortion: the bores stay round, maintaining the proper piston clearance and allowing the rings to do their job.
The A356 also has better tensile strength and mechanical properties which is important for the strength of the threads in the cylinder head pillar bolt holes, another failure prone area on triples. We are employing modern metallurgy, modern heat treating and modern machining methods to ensure more consistent quality and precision than was available when these motorcycles were made.

Big Bore kits made by boring out a stock block and installing new sleeves thin out the aluminum even more, further weakening the structure. These types of blocks have been known to crack around the base flange. Sure, this is a less expensive way to increase displacement but how often do you want to rebuild the top end?

Triples Rule offers other custom precision performance parts for Triumph and BSA motorcycles. Engineered to the closest tolerances, all Triples Rule parts are built to withstand constant use under the most difficult of conditions.

The manufacturers of Triumph and BSA motorcycles made great “production” motorcycles -  priced to be affordable. Triples Rule examined the parts of these fine motorcycles and then enhanced their durability with modern engineering, materials and CNC precision machining. The highest quality of raw materials are always used when making a Triples Rule part.

We provide the following items and services for Triumph and BSA motorcycles.