Engine Service: Road Race


Modern four-stroke engines are remarkable things. These technological marvels are the ultimate in performance and reliability for average riders as well as racers. Large doses of torque and linear power delivery make four-strokes the number one choice for road racing. In recent years the weight and reliability of these engines have made great strides and today, four strokes are the obvious choice.

Developing four-stroke power, however, is a study in incremental-ism. All of the reciprocating parts create friction and heat that detract from performance. As a result of this dynamic, building up the power is best approached in stages.

These engines are, in essence, many parts that together create a whole. If all the parts work in unison and in concert, large increases in reliable power occur. If only a few pieces of the whole are installed, you may create more problems than you will solve. All the pieces have to work together or you will concentrate stress loads and other negatives into specific areas, possibly ending with a Catastrophic Engine Failure.

At Yoshimura, we have been building four-stroke racing engines for over 50 years. We understand that your engine is the sum of many parts. We do not simply throw a big cam in, pop up the compression, and create a time bomb. Depending on which stage of engine modification you choose, we build power at self-sustaining, balanced levels.

We have our own in-house Isotropic Surface Finishing Process (ISF) department where we can blueprint your engines gear-sets just like Formula-1 machines. This technology not only let's your engine run "freer", but also lowers operating temperatures through decreased friction and proper interaction of reciprocating parts. We also have twelve Dyno cells (including two state of the art Onno-Soki units) and advanced computer diagnostics in everything from flow to metallurgical failure rates. There is no guessing here.

Stage 1 (Cylinder Head Only)
  Additional Services:
  • De-carbon combustion chamber
  • Intake and exhaust port and valve job
  • Confirm valve spring tension and condition of associated components prior to assembly
  • Machine gasket services
  • Mill head to increase compression ratio
  • Inspection and reassembly of top end
  • Complete Bottom-end assembly
  • Port and Polish Head: Single-Cylinder or Multi-Cylinder
  • ISF Transmission Process
  • Knife edge and balance crankshaft
  • Complete Race Spec Engine build for all classes
  • Installation of high performance engine components
    • Camshaft(s)
    • Crankshaft
    • Connecting Rod(s)
    • Piston(s)
    • Valve train components
Stage 2 (Cylinder Head Only)
  • Blend valve seats to cylinder head
  • Intake manifold blending
  • Light port shaping and valve job
  • Confirm valve spring tension and condition of associated components prior to assembly
Stage 3 (Cylinder Head Only)
  • Full Port and Polish
  • Reshape both intake and exhaust ports to optimize performance
  • Reshaping of combustion chamber
  • Complete valve job
  • Confirm valve spring tension and condition of associated components prior to assembly
Recommended Parts to Maximize GSX-R Power
  • Stage 1: High Compression Head Gasket
  • Stage 2: Camshafts, Valve Springs, Head Gasket, Pistons, Connecting Rods, ISF Transmission Surface
  • Stage 3: Camshafts, Valve Springs/Retainers/Cotters, Head Gasket, Pistons, Connecting Rods, Knife Cut Crankshaft, ISF Transmission Surface


For Further Information On Yoshimura Engine Services, Please Call Our Sales Department at (800) 634-9166