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CYCLECAR AND MOTOR CYCLE NOTES. [BT CELERITEIt] TESTING A LIGHTWEIGHT MOTOR CYCLE. A 100 MILES TRIAL. With a view to confirming my previously expressed views on the lightweight question I am making a number of trial runs on light- weight machines. Last year there were only two or three real lightweights on the market, but to-day there are quite a number of machines which appear to be really sound propositions, but in order to satisfy myself of the merits of some of these machines, I am putting some of them through lengthy tests, in order to form an opinion first hand. The first machine I decided to try was the "Triumph" 2 b.p. Lightweight. I approached the makers and they very kindly placed a machine at my disposal for the week end. After having the controls explained to me I jumped into the saddle and paddled away out of the works the engine started firing within a couple of yards and soon began to pick up speed. I was at first struck by the eweet yet rapid accelerating power of the engine; there is hardly any noise from the exhaust at 10/15 miles an hour, and the machine just glides over the ground with an entire absence of vibration. This absence of vibration is principally due to the two-stroke engine, which as most motor cyclists know has a firing stroke every revolution instead of every other revolution as in the case of the four stroke type commonly met with. This gives a more even torque or turning move- ment, and as the thrust on the piston is more nearly equal at all periods than in a four- stroke, this conduces to a smoother running engine. Apart from this however the weight of the moving parts is so very much smaller than in the case of a 3 h.p. engine that this gain tends to reduce vibration, so that with a two-stroke lightweight engine vibration is reduced to practically nothing. I found this to be the case with the Triumph engine at all speeds. Dodging traffic in the busy, narrow streets of Coventrv on a Saturday morning when the roads are slimy and wet is not an enviable task on a motor cycle—in fact it is, almost dangerous on the average "')!, h.p. machine, but I found the little lightweight perfectly tractable on the worst grease and in the thickest traffic. I would not mind riding a lightweight machine similar to this one through anything, but I would hesitate to do the same on a 3 h.p. machine. The riding position is so low ttiat one can stand astride the machine aud there is a space of several inches between one's body and the top of the saddle—therefore if the machine does try to skid it is a very simple matter to save one- self without having to bite the mud. Leav- ing Coventry for Birmingham I was soon able to test the springing and staying powers of the little machine, for the Coventry- Birmingham load is probably one of the worst in the country, abounding in pot holes and road waves as it does. The 18 mile journey took me just 50 minutes, which is an average of 21 miles an hour, which is pretty good for so small a machine especially when several miles of traffic are included. I later found that the machine was quite capable of averaging 25 miles an hour over ordinary flat and hilly country, but naturally in the first 20 miles or so I let the engine take things quietly. For the first five miles the engine kept chuckling to itself until I found this was backfiring through the carburetter, due to an incorrect setting of the carburetter. By closing the air slightly I stopped all the chuckling and the engine never back-fired once again. Going out into the country I gave the engine her head and found there was no difficulty in keeping the speedometer at 30 m.p.h. on the lever. At this speed thete is no vibration, nor has the engine any tendency to overheat or seize as is the case with some two-stroke engines I have tried. I never once heard a konk nor did the engine once dry up though I kept it all out for miles at a stretch. This is certainly a feather in the cap of the makers, for I believe the majority of the two-streke engines are prone to overheating and will momentarilly sieze up, and then go along again if driven all out for any length of time. Possibly the system of mixing the petrol with the oil has something to do with the success. As a hill climber I found the machine quite a revelation. She took the first part of Rose Hill, the gradient of which is about 1 in tt\- on top, and then I took to change down for the remainder and sailed over the brow at a good 20 m.p.h. The hill is nearly J of a mile long and the average gradient must be somewhere between 1.7 and 1.8. To test the flexibility of the engine I went down the hill again and climbed it as slowly as possible. I found it possible to climb the whole length of the bill with the speedometer steady at eight miles an hour. When one knows that a machine will climb such a hill at any speed from 8 miles to 20 miles an hour the extreme flexibility of the engine stands out very clearly. As a further test I gave the machine a flexibility test on the level. The top speed I was able to obtain was 35 m.p.h. on the level with no wind. On top gear the machine weuld quietly plod along at eight f miles an hour, and on the low gear it was possible to walk slowly alongside the machine vith the engine firing regularly at every stroke. This was at a speed of 3^ to 4 m.p.h. I certainly never would have believed that an engine could have been so flexible had I not made the test myself. It is curious how the noise of the exhaust influences one's calculations when trying to estimate the speed at which one is travelling with a 3! h.p. machine. Going at 40 miles an hour the exhaust is much quieter than that of this particular lightweight when going at 35 m.p.h., and the rapid series of explosions quite misleads one as regards the speed until the speedometer is glanced at. It struck me that the engine speed must be vary high in order to obtain the flexibility, but on working it out I find there is very little difference between the speed of the "Triumph" 2 h.p. engine and that of the 31 h.p. engine. With a top gear of 5 1/8 to 1 with 24 inch wheels, the speed of the engine is 2,500 r.p.m. at 35 m.p.h., whilst the speed of the 3l h.p. engine geared 41 2 to 1 with 26 inch wheels is over 2,000 r.p.m. Therefore it is easy to understand why the bigger engine vibrates more, and there must be more wear as the reciprocating parts are so much heavier, though the bearing surfaces are very little larger than those of the 2 h.p. engine, the inside of which I examined thoroughly. At 5 m.p.h. on top gear the engine speed of the lightweight is only 360 r.p.m., and it is remarkable that the engine will pull at this low speed as it does without any overheating or once miss- ing fire. Never once did the engine attempt to fire four stroke, though this is a common fault with some two-stroke machines at low speeds. I found the petrol consumption worked out at 97 miles to the gallon with a fair amount cf low gear work as I put the machine into a number of stiff pimples. Oil is mixed with petrol in the proportion of 12.1, so that on a 100 mile run roughly 1-12 gallon of oil would be used. The idea of mixing the oil with the petrol appeals to me strongly. Oil is simply fed from the oil tank into a measure which is incorporated with the Detrol tank filler cap, and 6 measuresfull are poured into one gallon of petrol, or in proportion, then one can ride on until all the petrol is consumed without ever having to think about lubrication of the engine. This system is next door to the all-automatic lubrication, and must appeal to the ordinary rider as well as the novice. A neat two-speed countershaft and dog clutch type of gear is fitted in the bottom bracket, and is controlled from the handle- bar by the lower half of the ordinary type of carburetter operating levers, the upper being used to control the magneto. The gear is well made-I examined it thoroughly when adrift-and the control is just as simple as that of the carburetter. To change down the lever is simply push forward-a light touch does it—nothing else need be moved, and to change up it is only to close the throttle for a moment whilst the change is being made, or as an alternative lift the release valve a moment. The engine drives by chain into the countershaft and thence by belt into the back wheel, and from what I could judge the belt should last from any- thing up to 6,000 or 7,000 miles. The machine complete weighed 1451 bs, and my own weight taken at the same time was 121- stone, so the machine bad no fairy to pull about. I carefully studied the whole machine in the garage, and can only find one fault with it--tha is in regard to the rear brake. This is placed inside the belt rim and thereby impedes the removal of the back wheel to some extent. I pointed this out to the makers, and they tell me they will probably fit the brake outside the rim. I am satisfied that the little "Triumph" is a machine which may safely be placed in the hands of the veriest novice, or in those of the business man who wants to average not less than 25 miles an hour over all sorts of roads and in auv weather, for steadiness in grease I have never yet baen on its equal. There are a number of other interesting points which I should like to mention, but unfortunately space forbids. I might men- tion that 21 in. by 2 in. tyres are fitted, and it might be an advantage to a heavy rider to have a 2} in. tyro on the back wheel. During the course of the 100 miles test, I never adj usted anything, beyond the car- buretter levers, and I see no reason why a thousand miles should not be covered on a simple type of machine such as this without any adjustment whatever.