DESCRIPTION

81 mm forged pistons made specially for us by our friends at JE in USA  from 2618 high strength alloy to suit 920cc Commando engines utilising standard conrods or our Carrillo lightweight rods - 11/16" dia gudgeon (wrist) pins. Flat topped, high compression to give optimum combustion chamber shape. Valve cutouts to accommodate oversize valves. (Cut outs 23.5mm radius on the inlets, 20.5mm radius on the exhaust pockets). Will give around 11:1 compression ratio depending on the state of your valve seats. A little surplus material on the shoulders to allow you to blend piston to the head depending on exactly how you want to do it. Will not match to a 850 head without some work - if they did they would be no good! Relatively easy to reduce compression ratio by facing off material from the top of the piston which is thick enough to accommodate this.

Supplied complete with pins, circlips & rings.

If running in bushless steel rods we recommend DLC coating on the pins.

Recommended .005" - .006" clearance to iron bores. xxxg each complete.

Price is for one pair (handed left & right) of pistons complete.

NEXT BATCH AVAILABLE AUGUST 2026