Here is the extraordinary story of Nigel Duff's home made RGV500 race bike. Thinking of men like John Britten, Kim Newcombe and Burt Munro it seems that New Zealanders are a special breed of people to make bikes like this!
All the information below comes from Nigel, many thanks for that!
"For about 4 years, from 1986 I raced the RG500 Gamma in Formula One in New Zealand. The final form was as follows,
17 inch Marvics, 5.5"rear 3.5" front,
Koni rear shock out of an Indy car,
Forcella Italia upside down forks,
Mercedes 190E radiator,
Dyson close ratio gearbox,
Mk9 RGB dry clutch,
Honda RC30 body work,
138kg, not sure of horsepower but faster than an Mk8 RGB that was out here in 1990,
¼ mile in 10.9seconds 132mph in fourth gear still setup for roadracing
managed to beat the then current NZ champion on a 1990 Suzuki GSXR1100. Stopped racing
for a while, basically because I got sick of tipping off the thing, plucking the carbs off and filling the engine up with dirt.
So I decided to build a V4 500 and put the carbs in the center of the Vee where they belong. That required a new frame swing arm etc. and so I built this thing.
Frame and swingarm is made from 6061 aluminium bulkheaded and gusseted monocoque a copy of the 1998 Suzuki RGV500, frame is 2mm thick, swingarm is 2.5mm. Swingarm is heat treated to t6 but frame is not done yet as I still may have to weld coil mounts etc to it.
I cast up a new crankcase to carry the 1990 YZ125 barrels in a 90 degree Vee with YZ heads and pistons (nice single thin ring pistons). I have made cranks from a TZ250H and have made the gears so that the cranks fit together as they used to and run on the RG500 layshaft.
A late model RS 250 ignition sits on the layshaft.
Gearbox is still the Dyson model. I had a heap of trouble with the standard Suzuki gearbox when I started racing and the Dyson unit was a lot of money at the time, but it was worth every penny. Never jumped out of gear in two seasons. I have replaced the two gears involved in second gear because it looked worn but it never gave any bother.
New gear set has not been used. Dry clutch uses factory outer basket and fiber plates , I machined the standard inner basket and steel plates to fit. Never had a slipping clutch after full power launches.
I knew a man who worked for Ohlins, so have a pair of 42mm customer 250GP forks fitted and a rear shock that once graced Doug Chandlers Cagiva.
Front brakes are 320mm Brembo rotors with Goldline calipers. Rear is a small Brembo off a mates TZ250,
both master cylinders are Brembo,
carbs are 35mm oval bored flat slide Dellortos.
The pipes I have made myself to patterns designed with the help of the software of Gordon Blair from the Queens University of Belfast (QUB) and I challenge you to find better pipes. One of the bottom pipes took me 32 hours.
QUB software has this thing at 140 hp with a relatively conservative bmep."
For more pics see