Motorcycles using Toyota Part's
Hickson Special
Many thanks to Brian Hickson for making contact and supplying the build details of his bike. I have posted them in full for all those people who like to know exactly what goes into creating such a motorcycle. Brian says the bike that reaches 87 km/h and costs 1.3c a kilometer on fuel to run.
Here are the build notes: The engine is a 376cc Kubota KND5B general purpose agricultural power plant, its intended use was driving water pumps, rotary cultivators, etc. The gearbox is a 1950's B.S.A. B31 standard ratio box, the clutch is a multi plate Triumph unit from the same era. Rear wheel is from a Honda CMX 250, not sure of the year. Front wheel is Suzuki GT 380, again not sure of the year.
Switch gear, tail light and front indicators are Yamaha RD 400, head lamp is Honda GB 250, rear indicators are Suzuki of some sort, not sure what. Twist grip is Honda CB 100, speedo is Suzuki, probably a small trailie. Handle bars are an after market item sold as British 12" risers. Front mudguard is Honda, rear is a standard mass produced trailer item. Seat is from a 1930s International tractor, the seat spring is half of an Austin A60 van rear spring main leaf.
The alternator is a Mitsubishi item, it is driven by a Honda Accord water pump pulley bolted to the inside of the engine flywheel. The frame is a double triangulated straight tube arrangement fabricated from 32 mm mild steel square section tube, the leading link system front forks are fabricated from 25 mm square section tube, again mild steel, the front coil over units originally graced the rear end of a CX 500 Honda. Steering head bearings are both taper roller bearings, the lower bearing has a 'built in' seal. The lower triple clamp is fabricated from 25 mm square section mild steel, the upper t/c from 19 mm
aluminum plate and the handle bar brackets from 25 x 50 aluminum bar.
Frame dimensions are wheel base 2040 mm (was supposed to be 2000 mm, slight hiccup there!), rake is 35 degrees and trail is 100 mm. I worked out these figures after considerable study of Foald & Willoughby's excellent text 'Motor Cycle Chassis Design: the theory and practice'. It was worth the effort, riding the machine is effortless! The handling is neutral and inputs required are minimal. Comfort is excellent, a 12 hour riding day is no problem. You have to do that now and again, with a top speed of 90 kmh (under ideal conditions) it takes a while to get anywhere! Average speed over a long trip is around 67 to 75 kph, depending on wind, hills, etc.
The fuel tank is fabricated from aluminum and holds 15 litres, enough for about 480 to 500 km. The primary chain (a 428 chain) is adjusted by moving the gearbox, the 520 final drive chain is tensioned with an adjustable slipper made from industrial nylon of some kind against the lower run of the chain, this
has proved to be very effective and much quieter than a roller. I tried a roller originally, that was stuffed after the first long trip, about 3000 km. The engine was originally fitted with a hopper tank for cooling, I replaced that with a built up top cover and thermostat housing, a 92 degree thermostat and a radiator fabricated from part of a Toyota single row radiator core, a shortened Holden top tank and a Mini bottom tank. Circulation is taken care of by the old fashioned but in this case highly effective thermosiphon system.
I drew up plans for the bike in January 1991, it hit the road in March 1994 and has since covered over 41000 km. Modifications carried out since then are the chain tensioner (already mentioned), the seat (the original was off a Harley 883 Sporty, this was the most painful thing I have ever sat on!), and engine modifications, namely a larger inlet valve, a thorough port job and an adjustable maximum fuel stop. I also built another muffler, the original was a bit noisy. I had initially geared it for a top speed of 100 kph, but with only about 7 hp (after modification) that proved to be a bit over optimistic, so on went a larger back sprocket and a smaller engine sprocket. The top speed of 90 kph (at maximum governed revs, upped to about 2900 from the original 2200), is
attainable at sea level on a flat road, no wind and with the ambient temperature below about 8 degrees Celsius.
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