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Cylinder Head Service
Cylinder Head Service
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The CRF300L's stock cylinder head leaves a lot to be desired. Sloppy casting, non-concentric valve seats, and other shortcomings are addressed with our CNC porting service, which includes a 5-angle valve job, head-resurfacing, plus new valves and seals.
The process starts with fully automated sculpting of the intake and exhaust ports on a 5-axis CNC machine. The combustion chamber also gets contoured. Then, the stock 3-angle valve seats are given a 5-angle profile. New OEM valves and seals are included, or you can upgrade to KPMI Black Diamond Valves for an additional $60.
With this porting service, total flow (measured in CFM) is increased by an average of 12 percent with this mod, increasing power across the rev range, but especially in the midrange (see dyno chart below). We have a specific Stage 3.5 ECU tune to match this setup.
Options explained:
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Assembled head: Send us your complete, assembled head and we'll port and service it and provide new OEM or Kibblewhite valves and seals. Assembly includes setting the valve clearances using a bench engine. Turnaround time is typically 2-3 weeks. Please specify your bike's year when ordering. Option upgrade: Kibblewhite lightweight spring set.
- Replacement bare head: If you want to retain your stock head for whatever reason we'll ship you a pre-ported bare head (with new OEM or Kibblewhite valves and seals included but not installed - they go on after the spring seat is set on the guide) that you can swap your ancillary parts onto. Please specify your bike's year when ordering.
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Assembled head: Send us your complete, assembled head and we'll port and service it and provide new OEM or Kibblewhite valves and seals. Assembly includes setting the valve clearances using a bench engine. Turnaround time is typically 2-3 weeks. Please specify your bike's year when ordering. Option upgrade: Kibblewhite lightweight spring set.
