Stroke: 50.5mm
Rod length 100mm
Bores Size: 50.42mm 1.9850"
Piston Size: 50.33mm 1.9814"
Clearance: 3.6 thou
Ex = 30.3mm 172deg
Tran = 40.0mm 122deg
Boost = 39.3mm 126deg
Valve close = 20.2mm 71.6deg
Valve Close = 43.8mm 130.1deg
RV clearance = 13thou
End Play = 8 thou
Timing = 2.3mm
Squish = 1.0 - 1.1mm
Combustion chamber = 7.0cc
Compression Ratio = 14.3 : 1
RPM limit 17,800rpm in stock tune
Rod length 100mm
Bores Size: 50.42mm 1.9850"
Piston Size: 50.33mm 1.9814"
Clearance: 3.6 thou
Ex = 30.3mm 172deg
Tran = 40.0mm 122deg
Boost = 39.3mm 126deg
Valve close = 20.2mm 71.6deg
Valve Close = 43.8mm 130.1deg
RV clearance = 13thou
End Play = 8 thou
Timing = 2.3mm
Squish = 1.0 - 1.1mm
Combustion chamber = 7.0cc
Compression Ratio = 14.3 : 1
RPM limit 17,800rpm in stock tune
This engine is one of the rarest quality
kart engines ever made. Initially made in very small (prototype)
numbers in 1982. Shipped to preferred distributors with an IBEA 26mm
Slide carby. Homologated in 1983. Largely ignored and rarely seen in
competition. Immediately superceded by the
Rotax DSA.
I run it regularly and run it hard. It is really quite quick. Particularly through the tighter sections. It revs to 17,800rpm pretty easily on quite tall gearing and pulls hard. Similar to a long stroke Parilla but with much more top end.
I have left it completely stock other than shaping the rotary valve to the shape of the port. Nevertheless it easily drives by current watercooled 125cc karts on practice days.
Inside, outside and dimensionally it's like a PCR Atomik I raced to many wins in the early 1990's. The Atomik seems to be a close clone of this engine without a split TT port.
This engine could be made a whole lot quicker by raising the barrel, earing the exhaust port and increasing the compression ratio to run on BP108 or similar fuel. Not that difficult. But I am not going to do that anytime soon.
The good news is it is a pre airbox era engine and the sound at full noise is a rarely heard symphony of the past. People can only image what a grid of 30 in the day was like. It is component perfect and even runs a Motorcraft AG403 plug today.
I run it regularly and run it hard. It is really quite quick. Particularly through the tighter sections. It revs to 17,800rpm pretty easily on quite tall gearing and pulls hard. Similar to a long stroke Parilla but with much more top end.
I have left it completely stock other than shaping the rotary valve to the shape of the port. Nevertheless it easily drives by current watercooled 125cc karts on practice days.
Inside, outside and dimensionally it's like a PCR Atomik I raced to many wins in the early 1990's. The Atomik seems to be a close clone of this engine without a split TT port.
This engine could be made a whole lot quicker by raising the barrel, earing the exhaust port and increasing the compression ratio to run on BP108 or similar fuel. Not that difficult. But I am not going to do that anytime soon.
The good news is it is a pre airbox era engine and the sound at full noise is a rarely heard symphony of the past. People can only image what a grid of 30 in the day was like. It is component perfect and even runs a Motorcraft AG403 plug today.
