Ninja400R Superbike CNC Ported Cylinder Head 2018/2021
$1,050.00 – $1,850.00
Kawasaki Ninja400R Superbike CNC Ported Cylinder Head will make your Kawasaki Ninja 400 an unbelievable little bike that feels like the ultimate superbike.
This product is legal in California only for racing vehicles which may never be used, registered or licensed for use upon a highway.
Ninja400R Superbike CNC Ported Cylinder Head
Spears Racing Kawasaki Ninja400R Superbike CNC Ported Cylinder Head will make your Kawasaki Ninja 400 an unbelievable little bike that feels like the ultimate superbike. Carefully tested and developed, the Superbike CNC Ported Cylinder Head will increase 3% to 5% in the mid to top end of the RPM’s and this is a big increase for a known commuter bike. You will be able to see in our pictures that both the Intake and Exhaust valve guides have been machined down to contour the ports for maximum intake and exhaust.
The Cylinder head will have a “Super Sport Style” valve job this will allow the valve surface to be moved to a different location to provide better flow and sealing. The valves will be install to a set seat pressure and installed height for maximum RPMs with no valve float.
When sending your OEM Stock head into Spears Racing Please provide the head complete
1ea. Complete cylinder head assembled(valves and springs still in the head
2ea. Camshaft Hold downs or Towers the main unit, and the one that covers the Cam chain Area and hold down bolts (secure the hold downs to the head with hardware)
Looking at making the most RWHP on your ninja 400cc add the Spears Racing Bored throttle Bodies
What is CNC Porting:
CNC porting is very precise because it is computer controlled. We can calculate the required cross sectional area and machine the port to that dimension every time (within less than .001”). We can also maintain consistent size throughout the port. Therefore, each port in the head will be identical and every ported head will be the same. This is a huge contrast to porting each head using grinding and sanding tools by hand.
A mirror finish of the port does not provide the increase that intuition suggests. In fact, within intake systems, the surface is usually deliberately textured to a degree of uniform roughness to encourage fuel deposited on the port walls to evaporate quickly. A rough surface on selected areas of the port may also alter flow by energizing the boundary layer, which can alter the flow path noticeably, possibly increasing flow. This is similar to what the dimples on a golf ball do.
Each cylinder head will have new Kawasaki Valve Keepers ( 16ea. 12011-1053) and Kawasaki valve guide seals ( 8ea. 92049-1349), no need to purchase them separate when the head is built ,like other companies selling their ported heads.
Spears Racing Kawasaki Ninja400R Superbike CNC Ported Head equals+1.5/3.0 RWHP across the range.