British Customs Performance Cylinder Head Update Service
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British Customs Performance Cylinder Head Update Service

  |   British Customs


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The Hinkley Twin powering your Modern Classic is a thing of beauty. Its also an incredible building block for riders hell-bent on their pursuit of more power. The British Customs Performance Cylinder Head Update Service has been designed with this specific type of street rider in mind.

Street riders performance needs differ from racers -- a usable increase in performance across the entire power band trumps unreachable top end, wide open gains.

To accomplish that task British Customs has developed the following polish and port process:
Cleaning and inspection -- The cylinder head is inspected for wear and tear.
Porting --The shape of the port is important to the performance of the head. The goal is to increase flow by 10 percent while maintaining a good ratio of intake to exhaust flow. We work the shape of the ports per the ap-plication and engine size.
Valve job -- To increase flow, a 3-angle-valve job is performed on the valve seats and then hand blended to maximize flow.
Blending ports -- Removes any edges, or irregularities in the ports to maximize flow.
Polish the chambers -- Polishing the chambers is done to increase low lift flow with a target number of 0 to 300,000.

  • Cleaning and inspection of head
  • Porting
  • Valve job
  • Blending ports
  • Polishing of the chambers
  • Surface, Measure, and set valve height
  • Assembly and measuring


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