Velocette Thruxton 500
VELOCETTE THRUXTON 500
CYCLE WORLD ROAD TEST
THERE'LL ALWAYS BE AN ENGLAND.
SEVERAL YEARS AGO, a manufacturing firm in the Orient decided to build a motorcycle which would appeal to riders all over the world. To this end, machines were purchased that best represented motorcycle engineering concepts in four different countries. England, long recognized as a "world power" in motorcycle construction, at first offered a slight problem as several manufacturers were producing the vertical twin engine, while many others were still selling great numbers of the ever-popular big single. After much Oriental pondering, it was decided that one motorcycle was more traditionally British than all the others, the Velocette. We inscrutable Occidentals here at CYCLE WORLD can only agree.
Although Velocette has pioneered several engineering advances, such as swing arm and telescopic fork suspensions, this firm has a reputation for design conservatism; a reluctance to completely depart from old traditions and habits. Certainly, a modern Velocette still resembles a twenty-five year old Velocette, more so than any other maker's current-versus-older model. This should not be taken entirely as criticism; many people want exactly what Velocette has to offer. However, two years ago someone would have been "bonkers" to think that Velocette, of all people, would put two colors of paint (other than black-and-something) on one motorcycle. Yet, this month's test bike, the "Thruxton", has a blue frame with silver tank and fenders. Some older enthusiasts would have been less surprised if one of the manufacturers of vertical twins had produced an all chrome-plated model.
Thruxton is an airport in the south of England where the Southampton & District Motorcycle Club has for several years now been organizing a five-hundred mile road race for production motorcycles. By far the most successful motorcycle in the 500cc category has been the Velocette. It is logical then that when the company decided to sell a machine of a touring-racing nature, it should be named after the "Thruxton 500" race — and so it was.
Dyed-in-the-wool Velocette owners boast that any Velo can be started on the first kick, but rarely can they produce when asked to prove it. We are sure the Thruxton would defy even the world's champion Velo starter, and the very large, racing carburetor does precious little to help an already sticky situation. Two of our staff members have been Velo owners in the past but no one could find the combination for kickstarting the beast into life and we finally had to revert to the tried and true, never fail "run and bump" start. One thing is certain, the person who buys a Thruxton will not be one of the electric starter bunch and is much more apt to be a "run and bump" fan.
Once started the Thruxton is very quiet because of the large fishtail muffler, which does an excellent job of silencing exhaust noises. Mechanical noise is at a minimum too, being almost inaudible. Velocette pioneered the high camshaft concept, where the cams are mounted high in the crankcase, permitting the use of rather short push rods. If careful attention has been given to tappet adjustment, the motor will be very quiet indeed, as our test machine proved. Although several manufacturers use the high camshaft principle these days, there are other design innovations throughout the motorcycle that are still quite exclusive to Velocette. For instance, the crankpin is not secured in the flywheels with nuts as is usually the case; instead, the portion of the crankpin that fits into the flywheels has a slight taper, and fits mating tapers in the wheels. There is a very effective lock when the assembly is pressed together, requiring in the order of four tons of pressure to separate the wheels again. The method appears to work as we have never heard of the flywheels coming apart or shifting by themselves.
Common Velocette practice for many years has been to mount the countershaft sprocket on the outside of the clutch. This feature enables very simple gear-swapping, especially for racing, but more important, it means that the primary chain runs "inboard" exceptionally close to the engine's centerline. By having the chain line close up to the engine a much shorter mainshaft can be used, resulting in less overhang, a design weakness of many engines. The bottom end assembly will be much stronger if the shafts are kept short and the undesirable overhang kept to a minimum. Velocette spends a great deal of time balancing the individual flywheels before they are built into an assembly; this, plus the rigid crank, undoubtedly accounts for the smoothness of the "big thumper."
Bore and stroke are equal on the Thruxton, being 86mm each or 3.385 x 3.385 inches. One would expect a higher rev limit with a "square" engine, and although the manufacturer states peak power at 6200 rpm, we were on the threshold of valve float at 6000. Since the machine had only one thousand miles on the odometer, we cannot blame valve float on worn springs, but rather that the manufacturer has quoted a limit and left no reserve. The 41 horsepower claim is probably very real and, if anything, on the conservative side. While the Thruxton is no great ball of fire as sports five-hundreds go, it does get down the road at a fair rate of knots. We suspect, and there are several 12and 24-hour records to back up our thinking, that the Thruxton will still be thumping down the road when many of its rivals are in the shop for tuneups.
The frame is a rather massive affair using chromemoly tubing. We always prefer double loop construction but it is not likely that this frame is going anywhere, that is in the way of bending or distorting. An effort has been made to minimize unsprung weight in the swing arm area, where tapered tubing is used for the arms; this means there is maximum strength at the usually underrated swing arm pivot, but minimum weight at the wheel spindle portion.
Velocette forks have always appeared to be rather long, and although fork travel does not feel long, the forks are heavily damped, more like those on a full-fledged road racing machine than any of the normal touring variety.
The seat is an enormous thing with the typical racing hump at the back, but quick calculations showed that a rider would have to be somewhere around seven feet tall to benefit from it. This is because there should be space on a touring machine for a passenger, and this brings us to another criticism; as we said, the seat hump is back too far for a normal size rider to utilize and the oil tank-battery box combination is too wide to allow one's knees to be used for grip.
The Thruxton has an abundance of chrome bits around the handlebars including headlight and its brackets. The exposed portion of the fork stanchions between the upper and lower fork crowns is also chrome plated. In addition to brake and clutch levers, there are compression release, choke lever and manual advance-retard lever; the secret in starting this motorcycle is finding the correct combination of all these levers.
A pair of Smith instruments, in the now common side-by-side arrangement, also decorates the steering head; these consist of an 0-8000 rpm rev counter and an 0-125 mph speedo. Due to the large, wide gas tank the clip-on bars must be kept well forward; couple this with a very high seat and the result is a "neck breaker" in town. At Riverside Raceway the Thruxton is more at home and the secret appears to be in settling into a racing crouch all the time. Don't fight it.
A motorcycle capable of speeds in the 100 mph region, with good handling to take advantage of it, must have good brakes and the Thruxton does. Probably one of the best features of the machine is the two-leading shoe, 7-1/2-inch front brake, well scooped for cooling, and we could not produce any measure of fade after several fierce applications. The rear brake is a single-leading shoe, 7-inch, which proved entirely adequate. However, with such an effective front stopper, the rear does not get a great deal of use.
The Velocette Thruxton 500 is a play racer's dream. Big singles have been dying over the past twenty-five years but they are still here, and will be here next year. We hope they never die.
VELOCETTE THRUXTON 500
$1240
