CYCLING AND MOTORING.

Taranaki Daily News, 24 March 1916, Page 7

CYCLING AND MOTORING.

ENGINE OVERHEATING. At this time of the metori,>ts who do much travelling are apt at times to strike overheating traubles. There are various causes which lead to an unduly hot engine. Either too weak or too rich a mixture will produce this effect. An extra air inlet, unless used with discretion,'may weaken the mixture unduly. The engine will generally take plenty of extra air when running fast with full or nearly full throttle, especially on rising ground. When it slows, however, the extra air should be reduced, and the same applies when running light, especially down hill. Often the mixture is completely upset by leaking induction pipe joints. Faulty ignition may also be responsible. This may be due to a "short" in the wiring, misfiring in the plugs resulting from a fracture »r the points being fouled with burnt 'Bil, or the magneto may need attentien, due to excessive lubrication, wearing of the platinum points or fouling of same. They need periodical cleaning and adjustment. The quality of the lubricating oil is of vital importance. The best is the cheapest. Cheap, poor oil means friction and excessive wear in the bearings. Order from a high-class firm, and give full particulars of the make of your engine, its size, etc. It should also be borne in mind that a- thicker oil should be used in summer than in winter. Cleanliness when lubricating is vital. If dirt or grit is allewed to get in with the oil it. will cause friction, and hence increased heat and wear. The oil should be carefully strained when replenishing the sump and gear-box. Both should be cleaned out periodically, and the same applies to the differential, which is generally lubricated with thin grease. When lubricating the minor bearings see that the lubricators are absolutely clean, especially in the case of screw-down greasers. These should be washed out with kerosene, the threads cleaned and the duct through which the grease is forced cleaned out, and kerosene squirted in and allowed to drain off before the grease cup is refilled and screwed home. Loss of compression will result in the overheating of the engine. It is generally due to the piston rings being worn, or to their working round until their slots coincide and so provide an outlet for the gases under compression to escape into the baee chamber. The trouble can generally be diagnosed by feeling the base chambe. by hand, It also allows oil to enter the combustion chamber, where it is converted into carbon, which becomes incandescent and causes pre-ignition, a very fruitful cause of over-heating. Thi s burnt oil also ii deposited on the valves and causes pitting, and this, in turn, results in the valves not being gas-tight, thus causing a loss of compression and allowing part of the gas to escape, while still burning, into the exhaust pipe, raising the tem- | perature of sane and of the contiguous parts *f the engine. The same may occur if the valve lift is insufficient I owing to wear of the tappets or faulty timing. Tn most modern cars, however, the tappets are adjustable for wear. I The adjustment should be made when the engine is hot. The space between ' the tappet head and the valve spindle, I when the valve is seated, should only be just sufficient to admit of a piece of notepaper being pushed, between when the tappet is at the lowest point. If there is insufficient lift, the valves open too late and close too early, thus retaining some of the burnt charge in the combustion chamber and putting a backpressure on the pistons. If the exhaust valves are wrongly timed pprtion of the gas may find an exit through the valve ports while in course of combustion, thus causing excessive heat. Also if the exhaust pipe or box is obstructed or wrongly designed there will be back .pressure which will restrict the outflow of the burnt bases and increase the heat o; the engine. If a fan is fitted behind the radiator it is essential that the belt should be kept adjusted so that it will not slip. If the fan forms part of the periphery of the engine flywheel, the .bonnet and undershield should fit closely, as otherwise the air-drawing effect of the fan will be partly nullified and the engine is likely to overheat on hilfe. The skill and judgment of the driver constitute important factors in keeping the engine reasonably cool. The ignition should not be retarded until an incipient knock indicates that it ia too far advanced. It is a fatal mistake when hill-climbing to remain on high gear as long as possible, especially if the day is 'hot or if there is a tail ivind. Under such circumstances the throttle ia pretty well open and the larger the volume of gas the greater the heat generated. In most cases also the Ignition is retarded to prevent "knock.'' Also, the slower the engine is running the less the cooling effect of the fan. The driver, therefore, should change down early. He will then be running with a smaller throttle opening and a moderate volume of gas, so that the heat developed will be much reduced. The fan will also be revolving at much greater speed, and therefore the volume of cool air induced will be increased, and the car will probably take the hill faster than if it had been kept struggling up it on high "ear. At the same time the engine should not be kept running on the lower gear at anything like its maximum spec), for this means nearly full throttl.' with the resulting increase of heat. Th.; same conditions influence the wat/:r and oil pressure pump. On the other hand, a very low engine speed means reduced pressure of water and of oil. The drivir should.seek to strike the happy medium. In the case of thermo-syphon circulation never fill the radiator to the top. This restricts the flow. The water level should not be higher than about l'.'.in below the bottom of the radiator filler. Finally, when overheating does occur, and the water boils furiously, do not re< plenish at once with cold water, It may result in a cracked water jaek u t. Stop the engine, remove the fUUv cap, slowly and carefully, lest the boiling water rush out, open the bonne',, mil wait for about ten or fifteen nvmites. 'IVn restart the engine and reploivsh the relator very slowly, so that the cold water will mix gradually with the hot. To test whether the engine has become dangerously hot, let a drop of water fall on the cylinder head. If it flashes inrto steam it may be taken as an indication that the pistons were perilously near to seizure. If it slowly fizzles away the temperature is not dangerously high.

NEWS AND NOTES. ■' In an endeavor to bring order out of the chaos of Russian motor truck transportation, particularly where Americanmade trucks are used, the. Russian Government has engaged an American expert to take charge of the entire business. , ■ ' • 9 * ' "•' " • An effort is to be made by an American motor cyclist to coyer 1,000 miles

in 1,080 consecutive minutes. The attempt is to be made on the New York speedway, at Sheepshead, which is claimed to be tlie fastest motor racing track in the world. The record looks feasible, for E. Baker in his recent 24 hours road ,ride in Australia covered 1027 miles in 1,292 minutes, and when one considers the many advantages of riding on a fast track as against a round road circuit, it certainly should make the feat possible.

Mstorists who are anxious to save running expenses should bear in mind that the. rate at which the car or motorcycle is driven is one of the important determining factors. The most economical speed both as regards pertol consumption and tyres is about twenty miles an hour. Above this the figure rises, especially as regards tyres. The increase is low at first, but after 25 miles an hour becomes much more rapid Heat is especially injurious to the tyres, and the economical motorist should occastest them by hand. It he finds that they are unduly hot he may take it as a warning that he has been driving too fast to suit his pocket. * * * It is estimated by the Motor Cycle (English) that there'are more than 20,000 motor cycles in use by tho Allies. While the figure cannot be regarded as more than an intelligent guess, it is probable it is not far wrong. The British Army is believed to have more than half of the number, while about onesixth is in use by the Russians. The motor-cycle is largely used by the French army, but the number they have is less than the British total. The Beigian army uses motor cycles to some extent, but of all the Allies it is probable that the Italians were best equipped in the matter of motor cycles when the war broke out. The value of the cycle, both of the pedal-propelled and mechanical variety, has long been recognised by the Italian military authorities, and their armies stationed on their mountainous northern frontiers have always been well equipped with machines of both classes. » • • Motor-cycle aide-caring is now becoming very popular in this country. In this connection it is of paramount importance that the side car wheel is kept in satisfactory alingment with the motorcycle wheels. This point, says the Dunlop Rubber Co., is not sufficiently realised by the average motor cyclist, who cannot understand why his tyres show undue wear. In the first place the life of tho tyres and easiness of steering depends upon perfect alignment. The best tyres that money and brains can produce will fail if the wheels are not properly set, the trouble in this connection being solely attributable to the rasping action set up by untrue running, caused through either the ignorance or negligence of the rider. Any side-carist whose back tyres show aiiy signs of undue wear should get his machine examined and tested, and in nine cases out of ten it will be found that' the trouble is caused by the side car's action on the back wheels.