Dellorto Motorcycle Carburetor Tuning Guide INSTALLATION

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Filed Under (Tips and Review) by admin on 01-02-2012

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The main Carburetor functions are: • To form a proper homogeneous inflammable mixture of fuel and air • To supply the engine with varying amounts of this mixture The fuel-air mixture is formed through vapourising and by uniformly spraying fuel into the airstream or at least by atomising it into very small droplets. Atomization takes place in this way: liquid fuel from the atomiser nozzle meets the flow of air which carries it, broken into very fine droplets, to the combustion chamber. We have spoken of a “proper” mixture because the mixture strength, defined as the amount of air in weight mixed with a fuel unit of weight, must have a precise value, ie it must be within the limits of inflammability so that the mixture can be easily ignited by the spark in the combustion chamber. lnflammmability limits for commercial petrol are: 7: 1 (rich limit ie. 7 kgs of air and 1 kg of petrol) , down to 20: 1 (lean limit ie. 20 kgs of air and 1 kg of petrol) . To obtain optimum combustion between these inflammability limits, a value very close to the so- called stoiciometric value is needed ie. about 14.5 – 15.0 kgs of air to 1 kg of petrol. A stoiciometric mixture ratio is one which ensures complete combustion of fuel with only the formation of water and carbon dioxide. The stoiciometric mixture ratio depends on the kind of fuel used, so if the fuel is changed, this fuel- air ratio will also change (see SECTION 5.1 ) .

MIKUNI VM CARBURETOR SUPER TUNING

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Filed Under (Mikuni) by admin on 31-10-2010

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This manual is intended as a guide for users of Mikuni carburetors who want to learn the adjusting method to the best performance from our products. In motorcycles, special tuning of the engine is now considereda routine practice. The arrows that appear in the drawings in this text show the direction in which air, fuel and an air-fuel mixture flows, respectively. ¢JAir Fuel “Mixture Mounting angle fore and aft inclination of the carb should not exceed approx Function of a carburetor The function of a carburetor is to produce combustible air-fuel mixture, by breaking fuel into tiny particles (in the form of vapor) and by mixing the fuel with air in a proper ratio, and to deliver the mixture to the engine. A proper ratio (mixture ratio or air-fuel ratio) means an ideal air-fuel mixture that can burn without leaving an excess of fuel or air, Whether the proper mixture ratio is maintained or not holds the key to the efficient engine operation, 2. Air-fuel mixture required by the engine (Fig. 1) The ratio of a mixture of fuel and air is called the mixture ratio or the air-fuel ratio and is generally expressed by the weight proportion. Theoretically, the amount of air required for complete combustion of 1 gram of fuel under normal conditions is

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