POWER TO WEIGHT RATIO
Something special - VE Hagon Suzuki
Success in competition comes through many factors – rider determination, lots of power or a light bike. We look at a package probably combining all three.
It is no great revelation to say a lighter motorcycle is easier to manage in the cut and thrust of the off-road world. Riders, be they clubmen or factory-backed, have tried to shed weight from their mount.
With factories having to guarantee motorcycles for public sale, often they would play safe in component choice but their contracted riders would sometimes be seen with thinly disguised lighter parts on their machines.
Look back as far as pre Second World War where differences between the catalogue road machine and the competition version would amount to a smaller capacity fuel and oil tank, narrower mudguards and a single saddle.
Later, into the 1950s, aluminium components started to appear on even big British motorcycles, all in the drive to make life easier for the rider and machine.
The lighter the bike the less stressed it is and the less weight an engine has to move the easier time it has, thus ensuring it will last a race.
Once the Japanese factories got involved in this motocross sport, such thinking was taken to new levels, often thanks to careful design and thought rather than too much fancy material. Weights dropped and all of a
sudden there were open class racers weighing in at well under 200lb. Not every maker could manage this and a few who couldn’t hinted to the FIM such machines were possibly too fragile. To back their case there is a great image of Joel Robert crossing the line in a GP with virtually just the cables holding the front end of his machine on. So a weight limit was introduced but that didn’t stop the strive for leanness in some areas.
With big two-strokes taking over from big four-strokes in the 500cc class as the 1960s melded into the 70s, thanks to their inherent lightness compared to engines with valves and cams and stuff, the four-stroke Mxer was almost consigned to history to await the arrival of the classic scene. Almost... The public, yes, you and me, suddenly became nostalgic for the sound of a four-stroke engine on the MX tracks. The factories didn’t fully understand this, nor did their research feel there would be a great market for such machines, so it was left to dealers, enthusiasts and yes, the sheer bloody-mindedness of people determined to go against the grain.
Helping this desire to see a four-stroke out on the track again was the introduction of Yamaha’s XT500 – here was a big single, not quite in the BSA Gold Star mould but close enough to appeal. It wasn’t long before these ohc 500 singles began appearing in other chassis rather than the road orientated Yamaha one. This coincided with the request from Hagon employee Terry Rowing to build a MX outfit using sheet aluminium, in his own time but at work. The request was granted, the project started but Terry had a road accident and the project halted. The concept intrigued boss Alf Hagon and he took it on as an official Hagon machine.
At that time, mid 1970s, Ton van Heughton was doing well in sidecar MX. He used the sheet alloy chassis with an XS Yamaha engine in it, won the European sidecar MX championship on it and thoughts turned to a solo version. Martin Hagon told us the first solo was built in October 1977, using an XT500 engine, in conjunction with Vic Eastwood.
Thankfully, for later generations and us journalists, Hagon kept meticulous records and Martin told us there were 50 bikes all told, most with XT engine variants in them – but one, this one in our feature, had an SP370 based engine in it. “It was built for Vic Eastwood,” says Martin, “and the Suzuki angle came because we’d just taken over the old Vic Camp race school and they were using Suzuki engines including the SP370. This particular engine has been bored and stroked to take it to 450cc so Vic could try it against the Yamaha-based machines.”
Sadly history records Vic didn’t get a chance to try the bike properly as he broke his leg at scramble in France shortly after the first outing, then broke the same leg again later in the 1979 season and decided to call it a day after
20 years at the sharp end of professional MX.
The Hagon alloy frames produced a light, rigid chassis with few heavy bolts and typically, for a company headed by a man keen to make every component earn its living, things were pared back to the minimum. It doesn’t take much inspection to realise the thought that went into the build with what looks like a petrol tank sitting atop the frame actually being part of the frame, or the rear brake lever pivoting on an engine mounting bolt and much plastic around for mudguards. Fasteners themselves are often in alloy, if they have to be steel then they’re drilled out to reduce their weight and so it goes on. Suspension at the rear is by Fox air shocks, state of the art in the late 1970s pre-mono era, while up front the forks were thought to be SP370 Suzuki but they don’t look quite right. It is possible they’re Yamaha YZ forks, the hubs may well be too, though the road test feature shows single-sided hubs similar to these ones on the SP test bike. To balance that, any contemporary images show different hubs on the SP to the one in the test. No doubt Suzuki enthusiasts will confirm or deny our thoughts.
Vic is quoted in the press as admitting he always wanted more power from the engines he used in these frames, going as far as saying until the Japanese makers took the four-stroke engine seriously and spent some development time on it there was little chance of it overtaking the two-stroke. The inference in there was the engine would perform better with the right attention.