Carburetors K63. Carburetor for Ural motorcycle

As always, before you start adjusting carburetors, you need to check and, if necessary, adjust the gaps between the spark plug electrodes, between the breaker contacts, between the valve stems and the ends of the rocker arms.

Idling. First you need to make sure that there is a gap of 2-3 mm between the tip of the cable sheath and the fitting. If it is smaller or larger, it is necessary to loosen the lock nut of the fitting and, turning it to the right or left, adjust the gap and lock the fitting with the lock nut. When a warm engine stops at a minimum speed without load, you should adjust the idle system of the carburetors, each individually, turning off the other cylinder. This is the order. Use screw 28 to set the minimum stable speed of the crankshaft, then gradually unscrew screw 29 until interruptions in engine operation occur, and then slowly tighten it until stable operation. Next, use screw 28 to again reduce the throttle opening until the minimum stable speed is obtained, while simultaneously adjusting the mixture composition with screw 29. Repeat these operations until the minimum stable speed of the engine shaft is obtained. Adjust the carburetor of the other cylinder in the same way.

After adjusting the idle speed, the crankshaft rotation speed when the left and right cylinders are running should be the same. This can be checked by ear by alternately turning off the right and left cylinders by removing the cap from the spark plug. If the engine speed differs when the right and left cylinders are running, the carburetors are again adjusted by screwing in screws 28 until the speed becomes the same. The stability of the engine is checked by sharply opening and closing the throttles (by turning the throttle handle).

If the engine runs stably at low speed, but stops when the throttle is opened sharply, you need to enrich the mixture by turning screw 29 a quarter to half a turn. If the engine stops when the throttle is suddenly closed, the mixture must be leaned out by turning screw 29 a quarter to half a turn.

Operating modes. Engine operation in such modes (medium loads) depends on the position of the needle in the throttle, so adjustment consists of choosing the correct position. The need for this appears when seasonal conditions change (summer-winter), during the break-in period, or to increase engine power (at the expense of efficiency). The adjustment is carried out by moving the dosing needle 25 along the thread relative to the bar 6, having previously loosened the lock nut 5. When screwed into the bar, the needle rises relative to the nozzle hole, and the mixture becomes richer, and when unscrewed, it becomes leaner. One revolution of the needle moves it by 0.5 mm.

Check the adjustment by sharply increasing the crankshaft speed. If you hear popping sounds in the carburetor, then the mixture needs to be enriched by raising the needle.

Fuel level. It is checked when there is increased fuel consumption or poor engine response, as well as when replacing a fuel valve or float.

To set the fuel level in the float chamber, you must dismantle the carburetor and remove the chamber cover and sealing gasket. When the carburetor is in a vertical position with the float chamber up, the belt on the side surface of the float (in the middle part) should be parallel to the plane of the carburetor body adjacent to the float chamber cover, and the distance between the belt and the same plane should be 13+/-1 mm. If necessary, the position of the float is changed by bending the stop 19 of the valve.

Rice. 1. Carburetor K63T:

Carburetor K-63 motorcycles Ural, Dnepr

Since 1985, K-63 type carburetors began to be installed on Dnepr motorcycles with the K-750M and Ural engines. The carburetors of both cylinders are identical in design and are interchangeable (Fig. 3.4).

The K-63 T carburetor with a horizontal mixing chamber, a central float chamber and a flat vertical stroke throttle includes a main metering system, an idle system, and a starting device. Its main parts are the float chamber and the housing cover 37 (Fig. 3.4).

The carburetor body contains the main fuel jet 13, the air channel of the main metering system, the nozzle chamber 7, the throttle 5 with a metering needle 34, the throttle spring 35, the low-speed fuel jet 14, the spray nozzle 11, the fuel inlet fitting 25, the float stopper 18, the adjusting screw low speed 24, as well as parts of the starting device 19-23.

Rice. 3.4. Carburetor K-63T: 1 - fitting with lock nut; 2 - throttle lift limiter; 3 - lock nut; 4 - dosing needle bar; 5 - throttle; 6 - body; 7 - nozzle chamber; 8 - air channel of the sprayer; 9 - float lever axis; 10 - spray body; 11 - spray; 12 - float chamber cover; 13 - main fuel jet; 14 - low speed fuel jet; 15 - lock washer; 16 - fuel valve stop for adjusting the fuel level; 17 - fuel nozzle of the starting device; 18 - float quencher; 19 - plunger needle; 20 - starting device plunger; 21 - spring; 22 - rod; 23 - starting lever; 24 - screw for regulating mixture quality at low speed; 25 - fuel inlet fitting; 26 - low speed jet air channel; 27 - air channel; 28 - fuel valve; 29 - float;
30 - channel for supplying the combustible mixture to the starting device; 31 - drainage hole; 32 - emulsion hole; 33 - via; 34 - dosing needle; 35 - throttle spring; 36 - channel connecting the float chamber with the environment; 37 - housing cover; 38 - screw for adjusting the low speed of the crankshaft at idle.

The carburetor body, body cover, float and nozzle chambers, as well as the tip of the starter plunger are cast from zinc alloy.

The carburetor cover contains a stop for the throttle control cable sheath, a throttle lift limiter 2 and a screw 38 with a rod for adjusting the low crankshaft speed at idle. The cover is attached to the body with two screws through a sealing gasket. The float chamber is connected to the environment using channel 36 in the carburetor body. There is a drainage hole 31 in the float chamber cover. A sealing gasket is installed between the float chamber and the body.

The lever-type float mechanism consists of two rectangular-shaped floats 29 connected to each other by a common lever. The floats and lever are made of caprolactam as one piece. The lever contains an axis 9 for attaching the float mechanism to the two columns of the carburetor body.

Fuel valve 28 is made of brass in the shape of a needle. A washer made of elastic material is installed in the upper conical part of the valve. The washer is practically not erased during valve operation, which makes it possible to ensure stability of the fuel level in the float chamber for a long time. At the bottom of the valve there is a groove through which the bottom valve is connected to the float.

The plunger has a non-separable design. It includes: a tip for connecting the cable; conical needle 19 and a spring designed to prevent the needle from jamming in the seat. The main system atomizer includes a housing and a nozzle that is pressed into the housing. The atomizer body has four radial holes.

The nozzle chamber is attached to the carburetor body along with the spray body. The L-shaped choke is made of brass sheet. It has two shaped holes. One of the shaped holes is intended for connecting the throttle to the control screw rod, the second is for securing the throttle control cable.

The protrusions fix the throttle spring in a vertical position. A radial cutout on the throttle wall, turned towards the air cleaner, creates a predetermined vacuum above the nozzle at idle at low engine loads.

The dosing needle is made of stainless steel. In its upper part there is a thread for movement relative to the sprayer, which makes it possible to use mixtures of different compositions in cases of engine operation under significant fluctuations in air temperature, as well as in cases of motorcycle operation in mountain conditions.

To enrich the mixture when starting a cold engine at low ambient temperatures (-15 °C and below), use float quencher 18 (Fig. 3.4).

If the engine is running at low speed, there should be a small amount of fuel mixture in its cylinders. To do this, the throttle is slightly raised with screw 38 by an insignificant amount. In this case, the vacuum in the area where the upper part of the nozzle is located is small and fuel does not flow out of it. Under the influence of vacuum in the mixing chamber behind the throttle, an emulsion flows out of hole 32, which is formed by mixing the fuel coming out of the nozzle 14 and air, which is supplied through channel 27. The fuel emulsion, when exiting the emulsion hole 32 into the mixing chamber, is sprayed by the air that enters at high speed into the gap between the lower edge of the throttle and the carburetor body, and enters the cylinder. When the engine operates at a higher crankshaft speed, it is necessary to increase the fuel supply. To do this, open the throttle, the vacuum increases in the area where the transition hole 33 is located, from which the fuel flows into the mixing chamber.

Screw 24 regulates the composition of the combustible mixture when the engine is running at low speed.

If you turn it away, the mixture becomes leaner, and if you turn it in, it becomes richer. The crankshaft rotation speed is regulated by screw 38. If you unscrew it, the rotation speed increases, and if you tighten it, it decreases.

In the event of a transition to the engine operating mode with a load, the throttle rises and the vacuum in the atomizer 11 of the main dosing system increases. Fuel flows out of the metering chamber through the nozzle 13 and the annular cavity between the metering needle and the walls in

the air flow of the main air channel of the carburetor, here the fuel is atomized, partially evaporated and then enters the engine cylinder.

The best mixture composition when the engine operates in loaded modes with low rotation speed is achieved by adjusting the position of the conical metering needle 34 and the main fuel jet 13. Using the metering needle, fuel is obtained in the most common engine operating range (approximately 3/4 of the throttle stroke). As the throttle moves upward, the annular cross-sectional area between the needle and the wall of the nozzle increases, as a result of which the amount of fuel passing through the nozzle increases.

When the throttle rises to its stroke, the composition of the combustible mixture in the mentioned engine operating modes is determined by the operation of the low-speed crankshaft rotation system. This is due to the fact that jet 14 is fed with fuel directly from the float chamber. Therefore, fuel is supplied directly through holes 32 - 33 of low idle speed into the main air channel, also in loaded engine operating modes. When the throttle is raised by 3/4 stroke, the flow area of ​​the air path in the area where the atomizer is located changes relatively little, so the air flow remains almost unchanged. Under these conditions, the amount of fuel that is supplied is determined mainly by the throughput of the main jet with minimal influence of the gap of the needle-nozzle pair. The mixture is further enriched.

Air supplied through channel 8 from the inlet pipe into the annular slot between the atomizer and its body improves the quality of the combustible mixture. Passing at a significant speed through the gap, the air transfers part of its kinetic energy to the more inert fuel, which exits the atomizer. In this case, the jet of fuel that comes out of the atomizer is thrown upward to the middle of the diffuser, which helps to improve the processes of crushing and atomizing the fuel, as well as its evaporation. In addition, the possibility of film formation on the walls of the gas-air duct is reduced, which increases the quality of mixture preparation in the carburetor.

Before starting a cold engine, plunger 20 is raised by lever 23 to the upper position. Under the influence of the vacuum that forms behind the throttle while the kickstarter cranks the crankshaft, fuel flows through nozzle 17 into the cavity under the plunger. Here it mixes with air, which enters through the channel from the carburetor inlet pipe, then, in the form of an enriched emulsion, passes through channel 30 into the mixing chamber and further into the engine cylinder.

The maximum enrichment of the mixture is achieved when the plunger is fully raised and is determined by the throughput of the nozzle 17. When the plunger is lowered, the mixture becomes leaner and the fuel supply is limited by the gap between the needle and the walls of the channel in which it is located. If the plunger is lowered completely, the needle closes the fuel channel and the fuel supply stops.

In K-63T carburetors, the mounting flange, compared to K-301 type carburetors, is rotated 90° and placed in a horizontal plane. Therefore, for their correct installation on MT and K-750M engines, a special spacer 4 is used (Fig. 3.5).

In 1985, instead of K301 and K302 carburetors, more advanced devices of the new K63 family began to be installed on Kyiv and Irbit motorcycles. The main technical data of K63 carburetors and their applicability on motorcycles and the K750 M01 engine are given in the table. The same devices are installed for the left and right cylinders.

DEVICE AND OPERATION

The carburetor is horizontal, with a central location of the float chamber and a flat vertical stroke throttle. It has two metering systems - main and idling, as well as a starting device. It consists of three main parts (Fig. 1): housing 8, float chamber 38 and housing cover 4.

Rice. 1. Carburetor K63T: 1 - fitting with lock nut; 2 — throttle spring; 3 — throttle lift limiter; 4 — housing cover; 5 - lock nut; 6 — dosing needle bar; 7 - throttle; 8 — body; 9 — air channel of the sprayer; 10 — axis of the float lever; 11 — spray body; 12 - sprayer; 13 — float chamber cover; 14 — main fuel jet; 15 — low-speed fuel jet; 16 — lock washer; 17 — channel for supplying the fuel mixture from the starting device; 18 — float; 19 — fuel valve stop for adjusting the fuel level; 20 - fuel valve; 21 — drainage hole; 22 — emulsion hole; 23 — transition hole; 24 — low-speed jet air channel; 25 — dosing needle; 26 - channel connecting the float chamber with the external environment; 27 — fuel inlet fitting; 28 — screw for adjusting the low speed of the crankshaft; 29 — screw for adjusting the quality of the mixture at low speed; 30 — air channel; 31 — trigger lever; 32 — shield; 33 - spring; 34 — plunger of the starting device; 35 — float sink; 36 — plunger needle; 37 — fuel jet of the starting device; 38 - float chamber.

The float chamber is connected to the external environment by channel 26 located in the housing. A drainage hole 21 is provided in the chamber cover. The lever-type float mechanism consists of two rectangular floats 18 connected by a common lever. The floats and lever are made of caprolactam as a single piece.

An axis 10 is inserted into the lever, securing the float mechanism to the two columns of the carburetor body. Fuel valve 20 is made of brass in the form of a needle. A washer made of elastic material is installed on its upper conical part, which practically does not wear out, and thanks to this, high stability of the fuel level in the float chamber is ensured. There is a groove in the lower part of the valve, through which it is connected to the float (thereby preventing it from hanging in the guide channel).

The fuel mixture from the starting device enters the carburetor mixing chamber through channel 17.
Plunger 34 is non-separable. It contains a built-in conical needle 36, a spring 33, which prevents the needle from jamming, and a tip for attaching the rod. The main system nozzle 12 is pressed into the housing 11, which has four radial holes. The U-shaped choke is made of brass sheet. A semicircular cutout on the throttle wall, facing the air cleaner, ensures a specified vacuum above the nozzle when the engine is idling and at low loads.

The dosing needle is made of brass or stainless steel. The upper part has a thread for movement relative to the sprayer. This makes it possible to change the composition of the mixture under load operating conditions with significant fluctuations in air temperature, operation of the motorcycle in mountainous conditions, etc. To ensure the desired composition of the mixture when starting a cold engine (ambient temperature minus 15° and below), the carburetor is equipped with a float stopper 35 . The carburetor body, its cover, float and nozzle chambers and the tip of the starter plunger are cast from zinc alloy.

When the engine is running at low speeds, the largest amount of combustible mixture should enter its cylinders, for which the throttle is raised by screw 28 by a small amount. Under these conditions, the vacuum in the area of ​​the upper part of the nozzle is small and fuel does not leak from it. At the same time, under the influence of vacuum, an emulsion enters the mixing chamber (behind the throttle) through hole 22, which is formed by mixing the fuel leaving the nozzle 15 and the air entering through the channel 30. It is sprayed by air flowing at high speed into the gap between the lower edge of the throttle and the carburetor body, and then goes into the cylinder.

When higher engine speeds are needed, an increase in fuel supply is ensured by the fact that when the throttle is opened, the vacuum in the area of ​​the transition hole 23 increases, from which fuel also flows into the mixing chamber. Consequently, at these revolutions it enters there through the emulsion and transition holes. The composition of the mixture is regulated by screw 29, and the rotation speed is controlled by screw 28. When turning screw 29, the mixture becomes leaner, and when turning it, on the contrary, it becomes richer, causing a corresponding increase or decrease in speed.

When switching to load modes, when the throttle is raised, the vacuum in the atomizer 12 of the main dosing system increases. Fuel flows from the float chamber through the jet 14, the annular cavity between the metering needle and the walls of the nozzle into the air flow of the main air channel of the carburetor. Here the fuel is atomized, partially evaporated and enters the cylinder. The composition of the mixture when the engine is operating under load conditions depends on the position of the conical metering needle 25, the throughput of the main fuel jet 14 and the operation of the idle system. Using a metering needle, the required fuel supply is ensured in the most common engine load range, corresponding to approximately lifting the throttle from one to three quarters of its stroke. As it moves upward, the area of ​​the annular section enclosed between the needle and the wall of the nozzle increases, and, therefore, the amount of fuel coming out of it increases. When the throttle is raised to a quarter stroke, the composition of the mixture is determined by the operation of the idle system. This is due to the fact that fuel enters jet 15 directly from the float chamber. Therefore, it is supplied through openings 22 and 23 of the idle system into the main air channel and under load conditions.

In the last quarter of the throttle stroke, the flow area of ​​the air path in the nozzle area changes relatively little, therefore the air flow remains almost unchanged. Under these conditions, the amount of fuel supplied is determined mainly by the throughput of the main jet with minimal influence of the gap in the needle-nozzle pair. At the same time, the mixture is further enriched, which is what is required for the engine to operate at maximum power modes.

The air that enters through channel 9 from the inlet pipe into the annular slot between the sprayer and its body significantly improves mixture formation. Passing at high speed through the slot, it transfers part of its kinetic energy to the more inert fuel, which exits the atomizer. In this case, the fuel jet is thrown upward to the middle of the diffuser, which improves the crushing and atomization process, as well as its evaporation. In addition, the conditions for the formation of an unwanted film on the walls of the gas-air duct are much worse. All this significantly improves the quality of the mixture prepared by the carburetor and reduces the sensitivity of the engine to changes in composition.

Before starting a cold engine, the plunger 34 is raised by lever 31 to the upper position. Under the influence of the vacuum formed behind the throttle when the crankshaft is cranked by the starter, fuel flows through jet 37 into the cavity under the plunger. Here it is mixed with air, which flows through the channel from the carburetor inlet pipe, then in the form of a rich emulsion is sent through channel 17 into the mixing chamber and then into the engine cylinder.

When the plunger is fully raised, the maximum enrichment of the mixture is achieved, limited by the throughput of the nozzle 37. When the plunger is lowered, the mixture becomes leaner and the fuel supply is limited by the gap between the needle and the walls of the channel in which it is located. When the plunger is completely lowered, the needle closes the fuel channel and the fuel supply stops.

ADJUSTMENT

As always, before you start adjusting carburetors, you need to check and, if necessary, adjust the gaps between the spark plug electrodes, between the breaker contacts, between the valve stems and the ends of the rocker arms.

Idling. First you need to make sure that there is a gap of 2 - 3 mm between the tip of the cable sheath and the fitting. If it is smaller or larger, it is necessary to loosen the lock nut of the fitting and, turning it to the right or left, adjust the gap and lock the fitting with the lock nut. When a warm engine stops at a minimum speed without load, you should adjust the idle system of the carburetors, each individually, turning off the other cylinder.

This is the order. Use screw 28 to set the minimum stable speed of the crankshaft, then gradually unscrew screw 29 until interruptions in engine operation occur, and then slowly tighten it until stable operation. Next, use screw 28 to again reduce the throttle opening until the minimum stable speed is obtained, while simultaneously adjusting the mixture composition with screw 29. Repeat these operations until the minimum stable speed of the engine shaft is obtained. Similarly, adjust the carburetor of the other cylinder.

After adjusting the idle speed, the crankshaft rotation speed when the left and right cylinders are running should be the same. This can be checked by ear by alternately turning off the right and left cylinders by removing the cap from the spark plug. If the engine speed differs when the right and left cylinders are running, the carburetors are again adjusted by screwing in screws 28 until the speed becomes the same. The stability of the engine is checked by sharply opening and closing the throttles (by turning the throttle handle).

If the engine runs stably at low speed, but stops when the throttle is opened sharply, you need to enrich the mixture by turning screw 29 a quarter to half a turn. If the engine stops when the throttle is suddenly closed, the mixture must be leaned out by turning screw 29 a quarter to half a turn.

Operating modes. Engine operation in such modes (medium loads) depends on the position of the needle in the throttle, so adjustment consists of choosing the correct position. The need for this appears when seasonal conditions change (summer-winter), during the break-in period, or to increase engine power (at the expense of efficiency). The adjustment is carried out by moving the dosing needle 26 along the thread relative to the bar 6, having previously loosened the lock nut 5. When screwed into the bar, the needle rises relative to the nozzle hole, and the mixture becomes richer; when unscrewed, it becomes leaner. One revolution of the needle moves it by 0.5 mm.

Check the adjustment by sharply increasing the crankshaft speed. If you hear popping sounds in the carburetor, then the mixture needs to be enriched by raising the needle.

Fuel level. It is checked when there is increased fuel consumption or poor engine response, as well as when replacing a fuel valve or float.

To set the fuel level in the float chamber, you must dismantle the carburetor and remove the chamber cover and sealing gasket. When the carburetor is in a vertical position with the float chamber up, the belt on the side surface of the float (in the middle part) should be parallel to the plane of the carburetor body adjacent to the float chamber cover, and the distance between the belt and the same plane should be 13 ± 1 mm. If necessary, the position of the float is changed by bending the stop 19 of the valve.

CARBURETOR CARE

Every 5,000 kilometers, it is recommended to wash and blow out the carburetors. Only jets can be washed with acetone and other similar solvents. It is not allowed to wipe parts with rags or other similar materials. To clean the jets, you cannot use steel wire, which can change the cross-section of their holes and, consequently, disrupt the operation of the carburetor. When installing the throttle, you must ensure that its cutout is facing the air filter.

When operating a motorcycle for a long time in hot climates (temperatures plus 35-40°C and above), as well as at an altitude of 2000 meters above sea level or more, it is recommended to lower the metering needle, and at an air temperature of minus 15°C and below, raise it. Fuel leakage through the drain hole 21 of the carburetor indicates a leak in the fuel valve of the float chamber. In this case, you should wash the valve or replace its elastic washer, eliminate the marks and nicks on the valve seat.

After running the motorcycle (mileage about 2500 kilometers), unscrew the carburetor mounting nuts, remove it, tighten the screws securing the spacer to the cylinder head, and open their heads.

INSTALLING A CARBURETOR ON "DNEPR" MOTORCYCLES OF PREVIOUS MODELS

In carburetors K63T, K63F, the mounting flange, compared to a carburetor of the K301 type, is rotated 90° and located in a horizontal plane. Therefore, for their correct installation (Fig. 2) on the MT and K750 M01 engines, a special spacer is used.

Rice. 2. Installation of the K63T carburetor on the MT engine: 1 - carburetor; 2 — bolt securing the spacer to the carburetor; 3 and 5 - gaskets; 4 — spacer; 6 — cylinder head; 7 — screw securing the spacer to the cylinder head.

Spare parts K63T and K63F are supplied complete with spacer 4, gasket 3, bolts 2 with nuts and washers, screws 7.

When installing K63T instead of K301 on previously released motorcycles “Dnepr-11” and “Dnepr-16”, K650, MT9, MT10, MT10-36, it is necessary to unscrew the studs from the head, insert bolts 2 into the spacer sockets and screws 7 to attach it to the head. Then attach the carburetor to the spacer with bolts 2 through gasket 3. Gasket 5 is taken from an old carburetor. If during installation the spacer rests against the cylinder fins or head, you need to file them in place.

The K750 M01 engine with K63F carburetors is also supplied with two sealing stepped rubber couplings assembled with clamps. When installing this engine on motorcycles M72, K750M and Dnepr-12, the inlet pipe of the right cylinder should be shortened locally (on the side of the carburetor by 8 mm and on the side of the corrector by 4 mm) and replace the old couplings with clamps with new ones.

F. SHIPOTA, KMZ engineer
E. PALMAN, engineer at LenCarZa

The K-63T carburetor with a horizontal mixing chamber, a central float chamber and a flat vertical stroke throttle includes a main metering system, an idle system, and a starting device. Its main parts are the float chamber and the housing cover 37 (Fig. 3.4).

The carburetor body contains the main fuel jet 13. the air channel of the main metering system, the nozzle chamber 7. the throttle 5 with the metering needle 34, the throttle spring 35. the low-speed fuel jet 14. the spray nozzle 11, the fuel inlet fitting 25. the float retainer 18, the adjusting screw low speed 24. as well as parts of the starting device 19-23.

Rice. 3.4. Carburetor K-63T: 1 - fitting with locknut: 2 - throttle lift limiter; 3 - lock nut: 4 - dosing needle bar: 5 - throttle: 6 - body: 7 - nozzle chamber; 8 - air channel of the sprayer: 9 - axis of the lever in melting: 10 - sprayer body: 11 - sprayer: 12 - float chamber cover: 13 - main fuel jet: 14 - low speed fuel jet: 15 - lock washer: 16 - stop fuel valve for adjusting the fuel level: 17 - fuel nozzle of the starting device: 18 - float stopper: 19 - plunger needle: 20 - plunger of the starting device: 21 - spring: 22 - rod: 23 - lever of the starting device; 24 - screw for regulating mixture quality at low speed: 25 - fuel inlet fitting; 26 - air channel of the low speed jet: 27 - air channel; 28 - fuel valve; 29 - float: 30 - channel for supplying the combustible mixture to the starting device: 31 - drainage hole; 32-emulsion hole; 33 - via; 34 - dosing needle; 35 - throttle spring: 36 - channel connecting the float chamber with the environment; 37 - housing cover: 38 - screw for adjusting the low speed of the crankshaft at idle

The carburetor body, body cover, float and nozzle chambers, as well as the tip of the starter plunger are cast from zinc alloy.

The carburetor cover contains a stop for the throttle control cable sheath, a throttle lift limiter 2 and a screw 38 with a rod for adjusting the low crankshaft speed at idle. The cover is attached to the body with two screws through a sealing gasket. The float chamber is connected to the environment using channel 36 in the carburetor body. There is a drainage hole 31 in the float chamber cover. A sealing gasket is installed between the float chamber and the body.

The lever-type float mechanism consists of two rectangular-shaped floats 29 connected to each other by a common lever. The floats and lever are made of caprolactam as one piece. The lever contains an axis 9 for attaching the float mechanism to the two columns of the carburetor body.

Fuel valve 28 is made of brass in the shape of a needle. A washer made of elastic material is installed in the upper conical part of the valve. The washer is practically not erased during valve operation, which makes it possible to ensure stability of the fuel level in the float chamber for a long time.

At the bottom of the valve there is a groove through which the bottom valve is connected to the float.

The plunger has a non-separable design. It includes: a tip for connecting the cable; conical needle 19 and a spring designed to prevent the needle from jamming in the seat.

The main system atomizer includes a housing and a nozzle that is pressed into the housing. The atomizer body has four radial holes.

The nozzle chamber is attached to the carburetor body along with the spray body.

The L-shaped choke is made of brass sheet. It has two shaped holes. One of the shaped holes is designed to connect the throttle to the control screw rod, the second is for securing the throttle control cable.

The protrusions fix the throttle spring in a vertical position. A radial cutout on the throttle wall, turned towards the air cleaner, creates a predetermined vacuum above the nozzle at idle at low engine loads.

The dosing needle is made of stainless steel. In its upper part there is a thread for movement relative to the sprayer, which makes it possible to use mixtures of different compositions in cases of engine operation under significant fluctuations in air temperature, as well as in cases of motorcycle operation in mountain conditions.

To enrich the mixture when starting a cold engine at low ambient temperatures (-15 °C and below), use float quencher 18 (Fig. 3.4).

If the engine is running at low speed, there should be a small amount of fuel mixture in its cylinders. To do this, the throttle is slightly raised with screw 38 by an insignificant amount. In this case, the vacuum in the area where the upper part of the nozzle is located is small and fuel does not flow out of it. Under the influence of vacuum in the mixing chamber behind the throttle, an emulsion flows out of hole 32, which is formed by mixing the fuel coming out of the nozzle 14 and the air supplied through channel 27.

The fuel emulsion, upon exiting the emulsion hole 32 into the mixing chamber, is sprayed with air, which enters at high speed into the gap between the lower edge of the throttle and the carburetor body and enters the cylinder. When the engine operates at a higher crankshaft speed, it is necessary to increase the fuel supply. To do this, open the throttle, the vacuum increases in the area where the transition hole 33 is located, from which the fuel flows into the mixing chamber.

Screw 24 regulates the composition of the combustible mixture when the engine is running at low speed. If you turn it away, the mixture becomes leaner, and if you turn it in, it becomes richer. The crankshaft rotation speed is regulated by screw 38. If you unscrew it, the rotation speed increases, and if you tighten it, it decreases.

In the event of a transition to the engine operating mode with a load, the throttle rises and the vacuum in the atomizer 11 of the main dosing system increases. Fuel flows from the metering chamber through the nozzle 13 and the annular cavity between the metering needle and the walls into the air flow of the main air channel of the carburetor, here the fuel is sprayed, partially evaporates and then enters the engine cylinder.

The best mixture composition when the engine operates in loaded modes with low rotation speed is achieved by adjusting the position of the conical metering needle 34 and the main fuel jet 13. Using the metering needle, fuel is obtained in the most common engine operating range (approximately 3/4 of the throttle stroke). As the throttle moves upward, the annular cross-sectional area between the needle and the wall of the nozzle increases, as a result of which the amount of fuel passing through the nozzle increases.

When the throttle rises to its stroke, the composition of the combustible mixture in the mentioned engine operating modes is determined by the operation of the low-speed crankshaft rotation system. This is due to this. that jet 14 is fed with fuel directly from the float chamber. Therefore, fuel is supplied directly through holes 32 - 33 of low idle speed into the main air channel, also in loaded engine operating modes.

When the throttle is raised by 3/4 stroke, the flow area of ​​the air path in the area where the atomizer is located changes relatively little, so the air flow remains almost unchanged. Under these conditions, the amount of fuel that is supplied is determined mainly by the throughput of the main jet with minimal influence of the gap of the needle-nozzle pair. The mixture is further enriched.

Air supplied through channel 8 from the inlet pipe into the annular slot between the atomizer and its body improves the quality of the combustible mixture. Passing at a significant speed through the gap, the air transfers part of its kinetic energy to the more inert fuel, which exits the atomizer. In this case, the jet of fuel that comes out of the atomizer is thrown upward to the middle of the diffuser, which helps to improve the processes of crushing and atomizing the fuel, as well as its evaporation. In addition, the possibility of film formation on the walls of the gas-air duct is reduced, which increases the quality of mixture preparation in the carburetor.

Before starting a cold engine, plunger 20 is raised by lever 23 to the upper position. Under the influence of the vacuum that forms behind the throttle while the kickstarter cranks the crankshaft, fuel flows through nozzle 17 into the cavity under the plunger. Here it mixes with air, which enters through the channel from the carburetor inlet pipe, then, in the form of an enriched emulsion, passes through channel 30 into the mixing chamber and further into the engine cylinder.

The maximum enrichment of the mixture is achieved when the plunger is fully raised and is determined by the throughput of the nozzle 17. When the plunger is lowered, the mixture becomes leaner and the fuel supply is limited by the gap between the needle and the walls of the channel in which it is located. If the plunger is lowered completely, the needle closes the fuel channel and the fuel supply stops.

In K-63T carburetors, the mounting flange, compared to K-301 type carburetors, is rotated 90° and placed in a horizontal plane. Therefore, for their correct installation on MT and K-750M engines, a special spacer 4 is used (Fig. 3.5).

Rice. 3.5. Installing a carburetor on an MT engine: 1 - carburetor; 2 - bolt securing the spacer to the carburetor; 3, 5 - gaskets; 4 - spacer; 6 - cylinder head; 7 - screw securing the spacer to the cylinder head

WHAT ARE THE DESIGN FEATURES OF THE K-65 CARBURETOR COMPARED TO K-63

The parameters of the K-65 carburetor dosing system have not changed. The throttle needle has changed in design (Fig. 3.6). In its upper part, instead of threads, there are five annular grooves. The needle is fixed to the throttle using a plastic plate 2 and a lock washer 1.

Rice. 3.7. Starting device of the K-65 carburetor: 1 - rod; 2 - guide; 3 - spring; 4 - plunger plug; 5 - plunger; 6 - lock washer; 7 - sealing washer; 8 - needle

Fig.3.6. Throttle needle K-65: 1 - throttle needle lock: 2 - bar; 3 - needle

With this design, adjusting the needle position is much easier. When regulating the quality of the mixture during engine operating conditions, it is necessary to rearrange bar 2 relative to the annular grooves of the metering needle, having first removed lock 1. A very important change was made to the design of the starting device (Fig. 3.7) - instead of a long needle, a short needle 8 with a sealing washer 7 was used This completely eliminated such a defect as the needle jamming and being pulled out of the socket. In addition, a rubber sealing cap is inserted into the upper part of the device. Now, through the gap between rod 1 and guide 2, dust and dirt will not get into the starting device. The top cover of the carburetor was also changed in order to prevent dirt from getting onto the throttle.

To increase reliability on the K-65, the design of the main dosing system sprayer was improved. Minor changes have also been made to the carburetor body. The rest is the same as in the K-63 carburetor.

WHAT ARE THE DESIGN FEATURES OF THE K-68 CARBURETOR

To replace the K-65 carburetor, a new K-68 carburetor was developed. In terms of dimensions and connecting dimensions, it is similar to K-65. At the same time, it has separate design features.

The K-68 carburetor has a cast choke with a round section. The fuel valve seat is removable. The diffuser is elliptical and equivalent to a diameter of 28 mm, the diameter of the mixing chamber is 30 mm. It is believed that the elliptical diffuser contributes to a smoother change in the amount and composition of the fuel mixture.

The throttle needle is constantly pressed in the direction of the flow, resulting in a high-quality outflow of fuel from the main metering system.

The throttle has a central drive, which ensures smooth regulation of the amount of mixture, and also reduces the wear of its rubbing parts! surfaces.

HOW TO INSTALL K-63T OR K-63F CARBURETORS ON MOTORCYCLES K-650, MT9, MT10, MT10-36, "DNEPR-11" AND "DNEPR-16" MODELS?

Carburetors K-63T and K-63F are received assembled with spacer 4, gasket 3, bolts 2, as well as nuts and washers. To install K-63T and K-63F carburetors instead of K-301 on motorcycles K650, MT9, MT10, MT10-36, "Dnepr-11" and "Dnepr-16", it is necessary to install spacers 4 and bolts 2 into the sockets, then screws 7 Attach spacer 4 to the head and secure the carburetor with bolts 2 through gasket 3. Gasket 5 is used from an old carburetor. If during installation the carburetor rests on the cylinder ribs, they must be filed down.

Rice. 3.8. Installing a carburetor on an MT engine: 1 - carburetor; 2 - bolt securing the spacer to the carburetor: 3, 5 - gaskets; 4 - spacer; 6 - cylinder head; 7 - screw securing the spacer to the cylinder head

Rice. 3.9. Spacer

A PISTON BURNT OUT IN THE URAL. WHAT IS THE REASON FOR THIS PHENOMENON AND HOW TO AVOID ITS REPEATMENT?

Burnout of the piston indicates that there is a serious disturbance in the flow of the working process in this cylinder and that these disturbances existed for a long time, but were not eliminated, although they probably revealed themselves (overheating, “popping” in the carburetor). It is most likely that the mixture in this cylinder was either lean due to incorrect adjustment of the main metering system of the carburetor, or this cylinder was working with constant overload due to the fact that the spool in its carburetor rose significantly ahead of the other. It is possible that the observed phenomenon was aggravated by setting the ignition too early or by prolonged driving at maximum settings, as well as by installing a spark plug that was too “hot” (with a low heat rating).

The causes should be eliminated in order, starting with the simplest: checking and installing the ignition strictly according to the instructions, replacing the spark plug. Then adjust the carburetors to ensure synchronized operation.

As always, before you start adjusting the carburetors, you need to check and, if necessary,
adjust the gaps between the spark plug electrodes and between the breaker contacts,
between the valve stems and the ends of the rocker arms.

Idling. First you need to make sure that there is
gap 2-3 mm. If it is smaller or larger, it is necessary to loosen the locknut of the fitting and,
turning it to the right or left, adjust the gap and lock the fitting with a lock nut. When
a warm engine stops at minimum speed without load, then
the idle system of the carburetors should be adjusted, each individually,
turning off the other cylinder. This is the order. Screw 28 to set the minimum stable frequency
rotation of the crankshaft, then gradually unscrew screw 29 until interruptions appear
the engine is running, then turn it slowly until it runs smoothly. Next screw 28
reduce the throttle opening again until the minimum stable speed is obtained, adjusting
at the same time the composition of the mixture with screw 29. Repeat these operations until
minimum stable engine shaft speed. Adjust the carburetor in the same way
another cylinder.

After adjusting the idle speed, the crankshaft rotation speed during left and right operation
the right cylinders should be the same. This can be checked by ear by turning off the
right and left cylinders by removing the cap from the spark plug. If the engine speed during operation
the right and left cylinders are different, the carburetors are adjusted again by screwing in screws 28 until
the rpms will be the same. The stability of the engine is checked by sharply opening and
closing the throttles (by turning the throttle handle).

If the engine runs stably at low speed, but stops when suddenly
opening the throttle, you need to enrich the mixture by turning screw 29 a quarter to half a turn.
If the engine stops when the throttle is closed abruptly, the mixture must be leaned by turning
screw 29 a quarter - half a turn.

Operating modes. Engine operation in such modes (medium loads) depends on
needle position in the throttle, so adjustment consists in choosing the correct one
provisions. The need for this appears when seasonal conditions change (summer-winter), in
break-in period or to increase engine power (at the expense of efficiency).
The adjustment is carried out by moving the dosing needle 25 along the thread relative to the bar 6,
having previously loosened the lock nut 5. When screwing it into the bar, the needle rises along
in relation to the nozzle hole, and the mixture becomes richer; when unscrewing, it becomes leaner.
One revolution of the needle moves it by 0.5 mm.

Check the adjustment by sharply increasing the crankshaft speed. If at the same time
If you hear popping noises in the carburetor, the mixture needs to be enriched by raising the needle.

Fuel level. It is checked when there is increased fuel consumption or
insufficient engine response, as well as when replacing a fuel valve or float.

To set the fuel level in the float chamber, you need to dismantle the carburetor and remove
chamber cover and sealing gasket. With the carburetor in a vertical position
with the float chamber facing up, the belt on the side surface of the float (in the middle part) should
be parallel to the plane of the carburetor body adjacent to the float chamber cover, and
the distance between the belt and the same plane should be 13+/-1 mm. If necessary
The position of the float is changed by bending the stop 19 of the valve.