CB750 Big Bore Engine

Many consider it to be the first superbike and we still think it’s worthy of that title.

As great fans and enthusiasts of the Big Four we feel like it’s time to have the CB upgraded to match the torque and power values of today’s motorcycle standards.

Having built strong race CB750 engines we know what works and how this unit responds to which modifications with our own Dyno facility to get the best out of every component and optimize power delivery and fuel efficiency.

CB750SOHC 836cc-850cc engines

The first step in our line of modifications to the OHC 750cc unit is a 12% displacement increase which doesn’t seem much but makes noticeable difference on torque values achieved by bigger pistons which aims at improving the engines torque figures which is what is most important for road use. You can send us your complete engine or just the barrels which will be bored and honed to suit the bigger forged pistons.

836cc Engine:

  • Barrels bored and honed to accept the larger pistons
  • Oversized pistons w/ rings – 65mm or 65.5mm

Under request we can also perform other modifications to complement the 836 Engine, including:

  • Hotter camshafts
  • Head porting to improve volumetric efficiency 
  • Bigger valves
  • Heavier valve springs
  • Race spec valve guides
  • Standard carburetors can be replaced by bigger, better units
  • Performance 4 into 1 exhausts
  • Ignition timing revised to suit all modifications
  • Crankshaft machining to knife edge with lightening and balancing.
  • Fuel injections system upgrade
  • Engines tested and tune in test bike before delivery

CB 750 SOHC 915cc-1050cc engines

This is our midrange option for those that feel like the standard displacement isn’t enough anymore and 836cc is too tame. RPE Racing has re-engineered the CB engine in an attempt to unleash all the torque of a v-twin engine into a very compact unit and still be able to enjoy the characteristic sound of the king of the Fours. We will use durable high quality sleeves to replace the original ones and the barrel and cases have to be machined to match.

We offer the 915, 970, 1000, 1030, 1050 engines.

The 915-1050cc Engines involve:

  • Re-sleeving of the barrels
  • Crankcase machined out to accept larger sleeves
  • Heavy duty conrods
  • 67.5 to 73mm pistons w/ rings

CB750 SOHC 1100cc-1200cc-1340cc engines

This is the ultimate package and very much in-line with our race engines and would be suited to all types of street use, trackdays, club events, etc.

These are one of kind pieces of engineering where almost every component has been modified and improved to maintain reliability and achieve a very enjoyable and powerful engine with a very deep tone. Many hours are put into an engine build like this and the final product is a reflection of just that. The biggest valves are used in the cylinder head with ports machined to match, the chamber is redesigned to improve efficiency, we will use our own custom designed rods which are race proven with lightweight pistons, a stroker crank is used in the 1340cc engine while both the 1100cc and 1200cc engines use the standard stroke, camshaft choices to suit purpose, the crank will be balanced and have the knife-edge profile. We also have available the choice of carburetted or fuel injected engines as well as the use of turbocharger or supercharger.

Other modifications available:

  • knife edge balanced crankshaft
  • copper head gasket
  • performance exhaust system
  • head porting
  • performance camshaft
  • revised ignition
  • larger carburetors
  • ceramic coated pistons.
  • fuel injection system upgrade

Any other wear parts inside the engine (bearings, timing chains, retainers, etc.) will be inspected and replaced.

Engines tested and tuned on the dyno in test bike before delivery.

Our highest performance CB Four engines have made more than 110hp on our dyno with amazing torque figures as well from the increased displacement.

Watch our YouTube Videos

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Honda CB 750 Barry Sheene Race 2016

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Honda CB750 (1200cc) Wakefield

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