916 CJS-racing headwork, refining stock parts


This 916 engine rebuild was a test of how to build a stock part only high power engine.

Chris at CJS Racing was contacted to rebuild the heads, for any questions regarding the design of those you find his shop at http://www.cjsracing.co.uk/

The idea was to use stock valves (33/29), stock piston, stock displacement (916cc), stock bip cams and stock 45mm exhaust.
What is changed are ports, seats and the heads are a bit skimmed to raise compression slightly. The engine was assembled with 1mm squish, cams timed to stock specs, then we made a new eprom for the setup after doing the basic setup resetting TPS and syncronising throttle bodies.

The goal was (the usual) to keep revs as low as possible, for driveability and longetivity. With the result in hand all parts of the goals were realised, a low rev, strong engine with broad power delivery. It idles very smooth but once you tell it to spin it most willingly responds with that hard sound from an engine in harmony.

Pretty neat result from a bike anno 1994, it will probably pull a few surpriced faces at the track this summer.