1975 HAGON-YAMAHA 844cc Motocross Sidecar Outfit
Built for victory
Londoner Alf Hagon is one of the great men of British motorcycle sports. Star of speedway and grass-track, sprint rider, engine preparer and manufacturer, Alf has done it all!
Pure Chance
But it was pure chance that led Alf to build the outfit that won the 1975 European Sidecar Motocross Championship. As he recalls: “One of my employees took part in local sidecar motocross competitions. When I saw his machine, I was not impressed: it was simply a modified motorcycle fitted with a sidecar. I decided to build a machine designed uniquely for motocross and nothing else.”
Winner From the Start
The chassis was built from sheet aluminum 2, 3 or 6mm thick according to the stresses to be withstood. The prototype was fitted with a Norton engine and won first time out in a British race. “We took it to the Sports and Racing Motorcycle Show in London. Ton Van Heugten saw it there and was impressed by it. He asked me to build him one with a Yamaha engine. We did it and he won the European championship with that motorcycle,” said Alf. The XS 650 Yamaha engine, enlarged by Hagon to 844cc, had a bore of 80mm, to take a JAP speedway piston and a stroke of 84mm (the original dimensions were 75×74mm). The cylinder head was fitted with BMC automobile valves ( 44mm intake and 38mm exhaust), and the standard ignition was replaced by coil and battery. The Hagon chassis only weighed 245 lb, including the magnesium wheels cast and machined by Alf Hagon. Production totaled 50 units, sold by Hagon in England and by Ton van Heugten in the rest of Europe.
SPECIFICATIONS
Engine: 844cc (80×84mm) air-cooled 360- degree parallel-twin four-stroke
Power Rating: 80 hp
Valves: single overhead-camshaft
Fuel System: carburetor
Transmission: 5-speed, chain final drive
Suspension: Hagan-Earles fork (front); swing arm with Girling elements (rear)
Brakes: Lockheed disc (front & rear)
Wheels: Hagan cast-magnesium (front & rear)
Weight: 353 lb
The Hagan-Yamaha ridden by Dutchman Ton van Heugten won the European Sidecar Motocross Championship in 1975.
