If you have an old rotary valve engine that deserves to be restored
contact me. I am really good at it and very particular.
100cc Air Cooled Rotary Valve Engine
Stroke: 50mm
Rod length 100mm
Bores Size: 50.24mm
Piston Size: 50.14mm
Clearance: 3.9 thou
Exhaust = 180 deg
Transfer 137 deg
Boost = 140 deg
Valve Open = 73 deg
Valve Close = 137 deg
RV clearance = 15 thou
End Play = 10 thou
Timing = 2.3 mm
Squish = .9 mm
Combustion Chamber = 6.6cc
Compression Ratio = 15.15 : 1
RPM limit >20,000rpm
Stroke: 50mm
Rod length 100mm
Bores Size: 50.24mm
Piston Size: 50.14mm
Clearance: 3.9 thou
Exhaust = 180 deg
Transfer 137 deg
Boost = 140 deg
Valve Open = 73 deg
Valve Close = 137 deg
RV clearance = 15 thou
End Play = 10 thou
Timing = 2.3 mm
Squish = .9 mm
Combustion Chamber = 6.6cc
Compression Ratio = 15.15 : 1
RPM limit >20,000rpm
A rare engine in perfect running order.
What an engine. In the 90's Honda's racing division, Mugen,
led the world. F1, Indy cars, GP bikes and on.
After years of development this was the final product homologated in 1992. It had success straight away but lacked racing team support
in Europe. Winning at the highest level is not just a fast engine.
Honda lost interest in such a tiny market.
Our team bought a brand new one from the Australian Distributor. The stock standard engine was shipped with 63/122 valve timing, too much compression, too tight a piston and lowish port timings. It exploded out of the corners but ran out of revs. Out of the box it suited being a clutch engine running on Methanol in the USA or more likely made to be setup and tuned by experts to suit local conditions.
I saw 3 through my workshop plus this one I bought later. Each has shown development at the factory level. I'm guessing the colour of the logo may give some indication of factory tune. Standard had no colour, then yellow, red, and green. This engine seems at the maximum state of tune for direct drive. Fully developed porting with big timings. And it is quick. 9/90 is not enough gearing. Wow!!
Honda showed the world how to rev a 100cc engine past 20,000rpm reliably. This engine dimensionally is close to the 1998 engines. It was years ahead of its time. This actual engine was raced at International level with success and brought back to Australia where it had a sorry tale. The last owner had no idea and basically wrecked it for parts. I got the aluminium castings and a crankshaft. Once cleaned up it was like new. It took me a year to collect the required original parts including conrod, header, valve and nut. New studs, bolts, piston, bearings and seals. Made the sprocket and ignition nuts. No luck with an ignition. So I fitted a motoplat with PVL coil. Way harder than it looks.
Our team bought a brand new one from the Australian Distributor. The stock standard engine was shipped with 63/122 valve timing, too much compression, too tight a piston and lowish port timings. It exploded out of the corners but ran out of revs. Out of the box it suited being a clutch engine running on Methanol in the USA or more likely made to be setup and tuned by experts to suit local conditions.
I saw 3 through my workshop plus this one I bought later. Each has shown development at the factory level. I'm guessing the colour of the logo may give some indication of factory tune. Standard had no colour, then yellow, red, and green. This engine seems at the maximum state of tune for direct drive. Fully developed porting with big timings. And it is quick. 9/90 is not enough gearing. Wow!!
Honda showed the world how to rev a 100cc engine past 20,000rpm reliably. This engine dimensionally is close to the 1998 engines. It was years ahead of its time. This actual engine was raced at International level with success and brought back to Australia where it had a sorry tale. The last owner had no idea and basically wrecked it for parts. I got the aluminium castings and a crankshaft. Once cleaned up it was like new. It took me a year to collect the required original parts including conrod, header, valve and nut. New studs, bolts, piston, bearings and seals. Made the sprocket and ignition nuts. No luck with an ignition. So I fitted a motoplat with PVL coil. Way harder than it looks.
