Professional snowmobile carburetor tuning. The carburetor is a device that is used in the power supply system of internal combustion engines and is designed to mix air with gasoline, respectively, a combustible mixture is created, and the carburetor must regulate its flow. There are updraft, downdraft, or horizontal carburetors, but downdraft models are the most common. This was due to certain advantages of such parts in terms of improving the filling of the cylinders with a combustible mixture, which leads to an increase in engine power. They are also more convenient for maintenance and repair.

In short, we can say that a carburetor consists of several main parts: a nozzle with a spray, a float chamber with a float, a diffuser and a throttle. The principle of operation of the carburetor is as follows. First, fuel enters the float chamber from the snowmobile tank, where the float and the shut-off needle resting on it float. When the required height of the fuel level is reached, the locking needle closes the tube, and the fuel supply stops. The fuel is consumed, and the float begins to descend, which, when a certain level is reached, again leads to the supply of fuel to the chamber.

The algorithm of work is not the most complicated, but the repair of a snowmobile carburetor is not limited to simply supporting the functioning of the float in the float chamber. After the appropriate diagnostic steps, you will need to adjust the optimal fuel level in the carburetor. After that, it is worth checking its operation at idle, with the throttle closed. If the initial settings are not the best, it will be quite difficult for you to set them yourself, since during idling the system operates throughout the entire throttle opening range.

Idle speed can be adjusted with a jet, a quality screw, which is located on the outside of the carburetor, and a quantity screw, which is responsible for engine speed. To further adjust the carburetor, you will have to tinker with the throttle at idle, varying the degree of its openness. We will not forget about cleaning, which is also included in the snowmobile carburetor repair service. To do this, you will need to completely disassemble it, thoroughly blow it out, clean it and reassemble it.

To carry out diagnostic work on the snowmobile carburetor and to ensure its high-quality repair, it is necessary not only to have high knowledge in this matter, but also to have special equipment available. Our service center pays great attention to diagnostics and repair. We have all the necessary equipment and are ready to carry out diagnostics and repair of the snowmobile carburetor in a short time.

Through fitting 20, it enters the fuel valve 15, which is equipped with an elastic locking washer. The valve rests on a tongue 18 connected with plastic floats 17, which are interconnected and freely rotate on the axis 16.

If for some reason the fuel level rises, its excess is discharged from the float chamber through the drain hole 32. So that the pressure in the float chamber does not increase when heated, it is connected to the atmosphere by an unbalancing channel 31. The main metering system consists of atomizer 5, the main fuel jet 6, throttle needles 7 and air supply channel 8. Fuel from the float chamber through the main fuel jet 6 enters the atomizer 5, rising under the action of vacuum through the gap between the atomizer and the throttle needle 7. channel 8 through the hole in the atomizer housing.The throttle needle ensures engine operation in medium modes and can be set to one of five positions.In the highest power modes, fuel consumption is determined mainly by the throughput of the main fuel jet.Reliable fastening of the atomizer is ensured by a lock washer 14 installed under the fuel pipe 9. The idle system consists, in turn, of the fuel pipe 9, the air channel 10, the mixture quality screws 11 and the mixture quantity 27, the idle hole 12 and the through hole 13. When the engine is idling under the action of vacuum in the mixing chamber behind the throttle, the fuel rises through the tube 9 and mixes with the air entering through the channel 10. The resulting emulsion, with a slight opening of the throttle (at low speeds), exits only through the hole 12. With a further rise in the throttle and an increase in speed, the vacuum in the zone of the hole 13 increases and through it the emulsion also begins to flow. Thus, the fuel supply increases as the number of revolutions increases. The main system for starting and warming up the engine. Carburettors of various modifications have different systems of enrichment devices: on K65S and K65V - a starting device with an autonomous drive; on K65G and K65Zh - with a cable drive; on K65I and K65D - corrector-enricher. Let's take a look at them in that order. Self-actuated starter consists of plunger 37, guide 35, return spring 36, starter needle 39, sealing gum 38, protective cap 29, control rod 40, as well as channels 33 and 34, fuel well A and hole 41. Normal the position of the device is closed. In this case, the needle 39 with the sealing gum 38 covers the fuel channel, and the side surface of the plunger 37 - channels 33 and 34. To turn on the starting device, you need to lift the rod 40 up and turn it about 90 ". In this case, the extrusion on the rod will come out of the grooves of the guide 35 and will be fixed on its upper end. The plunger will rise, opening channels 33 and 34 and the fuel channel 48. Under the action of vacuum fuel from well A will fall into the cavity under the plunger, mix with air and be fed into the mixing chamber in the form of an emulsion. To turn off the starting device, it is necessary, of course, to turn the rod back by about 90 °, after which the plunger will take its original position under the action of the return spring 36. The starting device is protected from dust and dirt by a rubber cap put on the spring guide 35. The starting device with a cable drive similar to that described - but it does not have a rod 40, and the position of the plunger 37 is regulated by a cable brought out to the lever. The corrector-enricher differs in that the fuel enters it directly from the float chamber (there is no fuel well A). Fuel consumption is limited by jet 43. With the plunger fully raised, the greatest enrichment of the mixture is achieved, which is necessary to start the engine. As the plunger is lowered, the mixture becomes more and more lean as the gap between the needle 42 and the channel wall decreases. When the plunger is fully lowered, the needle with sealing rubber 38 closes the fuel channel 48. An additional starting device (float sinker) is used at air temperatures from + 5 "C and below. Its use does not need explanations. Having considered the device and the principle of operation of individual systems, we right now to move on to issues of operation and adjustments.Before installing the carburetor, you need to remove its cover 2 with the throttle assembly.The cover is a rather complex subassembly, on which the throttle lift screw 27, guide 28, gasket 26, throttle lift limiter 30, throttle 21 and its spring 24, protective cap 29. The screw 27 is connected to the throttle by a rod. The throttle spring 24 simultaneously holds the needle 7 through the lock 22. The U-shaped brass throttle has two shaped holes and one round. The latter, located in the center, serves to installation and fastening of the needle, shaped on the side of the cutout - for fastening the gas cable, and T-shaped - for attaching the screw rod 27. The radial cutout on the throttle wall, facing the air filter, provides the necessary vacuum in the atomizer zone. Inside the cover there is a limiter 30 - it is recommended to remove it after the break-in is completed. After installing the carburetor on the engine, you need to attach a cable to the throttle and fix the cover on the carburetor. After that, use the throttle handle to raise the throttle and check if it fully opens the diffuser. Do this a few times to make sure the throttle doesn't stick in any position and that the diffuser closes and opens completely. Raise the throttle with screw 27 to such a position that a 2-3 mm gap appears between its lower edge and the diffuser generatrix. If the carburetor has a trigger or corrector, you need to unscrew part 35, remove the corrector assembly and attach the cable to piston 27, then install the assembly in place. Adjust the position of the stops 28 of the shells of the throttle and corrector cables (if the latter is available) so that they have a free play of about 2-3 mm (this is done so that the position of the throttle or corrector does not change when the steering wheel is turned). Tighten the screw 11 until it stops, and then unscrew it by 0.5-1.5 turns. Attach the fuel hose to the union 20. Make sure that the fuel does not leak at the connection points, and open the starting device or corrector. If, due to weather conditions or the individual characteristics of the engine, it is necessary to use a float damper, it is better to do this with the throttle fully open at the same time, then the reception efficiency increases. Gently pressing the kick starter, turn the crankshaft 2-3 turns, turn on the ignition and start vigorously. After starting and warming up the engine, the starting device or corrector must be turned off. In conclusion, let's talk a little about carburetor adjustments - every motorcyclist has to deal with them from time to time. It is more expedient to start with setting the fuel level. To do this, you need to turn the carburetor over, remove the bottom of the float chamber and measure the distance from the connector plane to the line dividing the float in half (a trace from the mold connector). This distance should be 13(+1.5/-1.5) mm. If on your carburetor the size does not fall within these limits, you need to carefully bend the tongue 18 of the float in one direction or another. In passing one more remark. If during operation the carburetor suddenly begins to "overflow", you need to check if the float has leaked. To do this, it should be immersed for at least a minute in a bath of hot water. Bubbles will appear - the float is thin, no - everything is in order. Before starting the adjustments, which will be discussed later, the engine must be warmed up. After that, lowering the throttle with screw 27, set the minimum stable idle speed, and then, slowly turning screw 11 in one direction or another, achieve an increase in speed to the maximum possible. Again with screw 27 try to reduce them, and then with screw 11 raise as far as possible. These operations sometimes have to be repeated 2-3 times. Now check how the engine reacts to the throttle. If, when the throttle is suddenly opened, it stalls, tighten the mixture quality screw 11 by 1 / 4-1 / 2 turns (the mixture will be enriched in this case); if the engine, on the contrary, stalls when the throttle is closed abruptly, screw 11 must be unscrewed by the same amount (the mixture will naturally become poorer). The quality of the mixture is adjusted in operating modes by moving the dosing needle 7 relative to the lock 22. You should start from its middle position. When the lock is moved up, the mixture becomes leaner (it is clear: the needle is lowered, and there is a smaller gap between its cone and the wall of the atomizer!), When the lock is moved down, it is enriched. The criterion for moving the needle can be the color of the insulator of the center electrode of the spark plug. If, after a run of about 30-40 km in normal operating mode, it has a whitish color, the mixture is poor and the needle must be raised at least one notch; if the insulator is dark brown, with traces of soot, the mixture must be made poorer by lowering the needle. Finally, if the motorcycle does not develop maximum speed, the main fuel jet should be replaced by installing another one with a larger diameter calibrated hole.

The atomization, evaporation and mixing of fuel with air is called carburation, and the device by which this is achieved is called a carburettor.

The transformation of fuel from a liquid state into a vaporous (gaseous) state is carried out in various ways: by spraying the fuel, by blowing small droplets of fuel with air, by lowering the air pressure in the place where the fuel is sprayed and evaporated, by heating the fuel, or by using easily evaporating fuel.

A number of requirements are imposed on the combustible mixture obtained by these methods. It should be such that the fuel was in a vaporous state by the time of its ignition, the composition of the fuel inside the cylinder was homogeneous, the composition of the mixture in all cylinders was the same, the combustible mixture ensured the most advantageous flow of the working process in this mode.

Withdrawal

Remove the intake silencer.

Disconnect the fuel supply line.

Unscrew the cover 1 of the carburetor, then pull the throttle 5 out of the carburetor.

Disconnect the cable from the throttle.

Loosen the clamps on the intake manifold rubber coupling, then remove the carburetor from the engine.

The assembled carburetor should be cleaned with common solvents and dried with compressed air before disassembly.

The carburetor body and jets must be cleaned with cleaners.

Check filter 15 for clogging. Clean or replace if required.

Check the condition of the needle valve 16. If it is defective, the needle and valve seat must be replaced as a set.

Check throttle for wear. Replace it if necessary.

Check that the idle speed screw 7 is not bent. Replace if necessary.

Check if there is fuel in float 12, replace if necessary.

Check the float for cracks or other damage affecting free movement; replace if necessary.

All carburetors have an identification marking on the body.

Identification

Example  34-560 - the first two digits indicate the diffuser diameter in mm.

Disassembly and assembly

Remove the screws from the stop plate 4 to remove the needle 3.

The position of the needle in the throttle is adjusted by means of the needle lock 2 inserted into one of the five grooves located on the top of the needle. Position 1 (at the top) corresponds to the leanest combustible mixture, 5 (at the bottom) - to the most enriched.

NOTE: The last digit in the needle identification number gives the recommended needle lock position from the top of the needle.

Castle position

Carburetor float adjustment

The correct position of the float in the float chamber of the carburetor is essential for maximum engine efficiency. To check that the float position is correctly adjusted, proceed as follows:

remove the float chamber 11 and the gasket from the carburetor

make sure float bracket 9 is symmetrical - not deformed

with the carburetor positioned upside down on a flat surface, measure the height H between the body surface and the top edge of the contact foot. Hold the ruler vertically, parallel to the axis of the float and in the same plane as the axis of the main jet opening.

For height adjustment H

bend the float contact tab until the desired H value is reached (see section 10-01).

Illustration of the operation of the metering elements depending on the throttle lift

NOTE: Refer to the "Technical Data" section and the "Spark plugs" section for a thorough study.

Install the carburetor in the reverse order of the removal procedure. Before setting the carburetor, check the condition of the body and the throttle cable (triple cable).

Install the worm-drive clamps so that their tightening bolts are misaligned - not aligned.

Install the throttle cable into the needle stop plate

NOTE: Do not block the hole in the throttle when installing the needle stop plate. This is an important condition that allows the carburetor throttle well to be breathed.

Make sure you have plastic needle seals.

Installing the needle in the choke

Needle lock

Needle stop plate

Screw

Needle

plastic seal

Throttle

Throttle cable

Carburetor adjustment

1. Idle screw

Idle mixture quality screw (air screw)

Preliminary adjustment of the carburetor with the engine not running

Fully, but not tight, tighten the idle mixture screw 6, and then loosen it in accordance with the data given in section 10-01. By turning the screw clockwise, we enrich the mixture and, conversely, by turning it counterclockwise, we deplete.

Completely turn out the idle speed screw 7 - it should not come into contact with the throttle. Loosen the locknut of the throttle cable adjusting screw, select the cable play.
Press the throttle lever all the way down - the lower edge of the throttle should be flush with the top of the diffuser or no more than 1 mm lower (engine side). If necessary, turn the adjusting screw to adjust the throttle position.

Lid

Gap

Throttle

Tighten the locknut after adjustment is complete.

When adjusting the carburetors of a two-carburetor engine, pay attention to the synchronism of the opening of the throttle valves - both dampers must open simultaneously. If necessary, adjust the position of the throttles with the adjusting screws of the triple cable.

Using the idle speed screw, set the gap between the lower edge of the throttle (engine side) and the diffuser to 1.5 ... 1.6 mm. (When setting the gap, use a wire or drill of the correct diameter).

Drill bit used as gauge

Final adjustment of the carburetor with the engine running

Start the engine and let it warm up, then adjust the idle speed (See Section 10-01). by turning the idle speed screw 7 (both screws in the same way - for two carbureted engines) clockwise to increase engine speed, or counterclockwise to decrease them.

Set the lever 17 of the fuel corrector plunger to the “Open” position

Fuel corrector plunger lever in the "Open" position

Use small tool diameter for VM 32 carburettor.

Insert the plunger tool into the air passage of the carburetor fuel corrector. The tool stop must be within 1 mm of the recess wall.

View from the intake silencer

Tool stop within 1 mm of the recess wall

If the tip of the tool does not fit under plunger 18, adjust the plunger position as follows.

Make sure the plunger lever is in the "Open" position.

Lift up the protective cap and loosen the fuel equalizer cable adjusting screw locknut as shown in the following figure.

Lift up the protective cap

Loosen locknut

Turn the fuel trim cable adjustment nut until the tool is properly seated under the plunger.

NOTE: Light pressure is required to insert the tool under the plunger.

Check for correct adjustment set lever 17 to the close and open positions and ensure that the tool is properly seated under the plunger only when the lever is in the fully open position. Set the lever to the "close" position and check for play in the fuel corrector cable.

Snowmobiles "Buran" are equipped with several types of carburetors. One of the most popular fuel devices is the Mikuni Buran carburetor. It is an economical trouble-free mechanism. Due to its simple design, easy maintenance, it has won a lot of fans all over the world. All owner reviews of this type of carburetor are invariably positive.

Types of carburetors

Exploitation technical means in winter, it requires a special approach to the quality of the main components and mechanisms. The preparation of the fuel mixture is carried out at constant sub-zero temperatures. Therefore, in the Buran snowmobile, the manufacturer practices the installation of a Mikuni carburetor on the Buran snowmobile.

Mikuni carburetor on Buran

As an analogue for Russian snowmobile enthusiasts, the manufacturer often uses the installation of Chinese carburetors with the same name. Since the carburetor components are exactly the same, it is necessary to choose a carburetor carefully so as not to confuse their manufacturers. For complete certainty, it is necessary to require supporting documents and certificates from the manufacturer's country from the seller.

Mikuni carburetor device on a snowstorm

The Mikuni carburetor is a single-chamber mechanism with a central float chamber. The design of this assembly uses a cylindrical vertical stroke choke. There is no need to use complex tools and expensive fixtures to mount the carburetor.

This carburetor is good because it is attached directly to the engine nozzle with two M6 bolts. It is not necessary to adjust the gaps, the fastening is rigid, classic, through two rectangular gaskets made of petrol-resistant rubber. The cross section of the gasket material is 1 mm; the gaskets are glued onto rectangular pipes in special grooves for attaching to the engine.

A diffuser and a rubber adapter are installed between the engine and the carburetor. Fuel is taken from the sump filter and the fuel pump through an elastic rubber hose with a cross section of 10 mm to the carburetor intake fitting. Next to it, a 3 mm pump hose is connected with a thin transparent PVC tube.

From the control handles of the snowmobile "Buran" two cables are stretched. One cable controls the fuel supply, it is called gas, the second cable controls the enricher - the air damper. Both cables are equipped with bosses that are easily inserted into the working attachment and control units.

Overall and connecting dimensions of the Mikuni carburetor:

• the distance between the M6 ​​bolts for mounting the carburetor - 48 mm;
• diameter of the passage hole for the fuel mixture entering the combustion chamber - 26 mm;
• the total height of the case is 138 mm.

The design of the mechanism uses a simple round-throttle damper. This node is made in the form of a full-fledged suction, which has two positions:

⇓ First position – flag is down. The fuel channel is closed in this position.

⇑ Second position - the flag is raised. The fuel channel is open in this position.

The principle of operation of the air damper

With two choke positions, the Buran's Mikuni carburetor is the most dynamic and responsive fuel delivery mechanism of any snowmobile in its class. This choke is truly unique among most snowmobiles operating in harsh winter conditions, in severe frost.

The presence of two full-fledged working positions allows you to qualitatively regulate the amount and volume of the enriched fuel mixture entering the ignition chamber of the internal combustion engine. Below (Fig. 2) is an analysis of each of the positions of the air damper.

In the standard position, when the lever is lowered, the additional channel for the enriched fuel mixture is closed. The snowmobile engine receives only the amount of fuel that is directly supplied by the carburetor.

Open channel position. The flag is raised, the additional channel for supplying the fuel mixture is open. Additional fuel enters the combustion chamber of the engine, the power unit develops maximum power.

The role of the flag in the carburetor

It is not in vain that the carburetor on Buran is equipped with a special flag that serves to open an additional channel. This node plays a crucial role in power characteristics, starting a cold engine in winter, and the speed of warming up the engine on a snowmobile to working condition.

Rice. 2. The main elements of the Mikuni carburetor: 1 - a flag, 2 - a fuel intake fitting, 3 - an adjustment screw, 4 - a pumping fitting.

If you put the flag up, the engine starts to receive a significantly larger amount of fuel. At this point, the snowmobile is running at higher speeds. crankshaft. The use of a flag greatly facilitates the operation of the entire mechanism in the cold season: in autumn, winter, early spring, in frost and cold.

Drivers who constantly operate snowmobiles during the autumn-winter season use this device when starting a cold engine in the morning. The mechanism that has cooled down overnight is much easier to start if you raise the flag up. Quick high-quality start-up, accelerated warm-up greatly facilitate the operation of the snowmobile.

After starting a cold engine, the mechanism that has cooled down in the cold overnight should be thoroughly warmed up. The checked box allows you to do this much faster than the standard mode. The snowmobile will work for some time on suction, quickly warm up and you can hit the road.

A well-heated engine runs stably, without pops, jerks, or difficulties. After normal warm-up, the flag goes down and takes the standard position. Then the machine is operated in the usual operating mode.

An engine that has reached operating temperature needs a small amount of fuel mixture for stable, trouble-free operation. In a similar rhythm on a snowmobile, the engine enters an economical fuel consumption mode and can be operated for a long period of time.

Mikuni carburetor adjustment on Buran

Precise adjustment of the air-fuel mixture supply mechanism for the Buran snowmobile engine provides:

• instant start without difficulty;
• stable operation during operation;
• significant fuel savings;
• the best safety of spare parts, accessories, details.

Adjusting the idle speed of the Mikuni carburetor is carried out in the following order:

1. Before starting a cold engine, turning screw 5 sets the throttle to a position so that there is a gap of 2 ... 2.5 mm between the lower generatrix of the carburetor body and the throttle base.

Rice. 3. Mikuni carburetor adjustment.

1. Adjustment screw 4 must first be fully tightened, then unscrewed by 0.5 ... 1 turn.
2. Start the engine, warm up for 2 ... 3 minutes at an average crankshaft speed.
3. When tightening screw 5, it is necessary to set the minimum possible speed of the engine crankshaft.
4. Gradually unscrewing the screw 4, to achieve the appearance of interruptions in the operation of the engine. Slowly twisting, find the optimal position of the screw 4. The engine should run at the lowest possible speed without pops, jerks, interruptions.
5. Check the stable operation of the motor by sharply opening and closing the carburetor throttle. In the case when the power unit stalls and stops from a sharp opening of the throttle, it is necessary to tighten screw 4 by a quarter or half a turn.

The fuel mixture will be rich. In the case when the engine stalls and stops at the moment of abrupt closing of the throttle, it is necessary to unscrew the screw 4 by the same number of turns. The fuel mixture will be lean. If the carburetor is adjusted qualitatively, screw 4 is unscrewed by no more than two turns from the fully wrapped position.

By unscrewing the carburetor adjustment screw by a large amount, they create a poor fuel mixture in operating conditions. With such a free attitude to adjustment, the engine may overheat and the unit may jam.

Mikuni carburetor for snowstorm is an excellent technical solution for a snowmobile. Its installation and operation greatly simplifies the winter chores of the owner. Adjusting the mechanism is easy. It’s better to set it up correctly once, so that you don’t look in all winter later. Owners give only laudatory reviews about this carburetor.

Adjustment, installation of fuel injection is carried out in the fall, it is better before the onset of sub-zero temperatures. Usually every snowmobile owner who has adjusted his unit since the fall, rides without worries all winter. You won't have to adjust until spring.

It can be seen from the article that the described type of carburetor is reliable, durable, unpretentious. The mechanism is simple, without technical excesses, so all reviews about it are only positive. Wide unification, stable operation in any frost. The author recommends installing Mikuni carburetors on snowmobiles, motorcycles, all light vehicles without a doubt. This technique will not fail.

Important: Avoid fakes when buying a mikuni carburetor, see the video on how to recognize a fake:

Carburettors that are most often on a snowmobile snowmobile and their characteristics

Most often, carburetors on Burana were used in the K-65Zh model range, there are also K-62, but it actually does not differ from the 65th. Well, membrane carburetors are probably no longer in operation.

Scheme of the carburetor K - 65ZH: 1. Cover; 2.Throttle; 3. Throttle lift limiter (not available for K65B, K65K, K65Zh, K65P); 4. Throttle lift screw; 7. Screw mixture quality; 8. Fuel-conducting fitting; 9. Handle of the trigger rod (only for K65B, K65V, K65K, K65P, K65S, K65F; for other modifications, pos. 19; 10. Float sinker (for K65A, K65L is absent); 11. Drainage hole (for K65A, K65L is absent ); 12. Dosing needle; 13.3 dosing needle holder; 14. Idling transitional hole; 15. Idling hole; 16. Main system fuel jet; 17. Idle dosing tube; 18. Nozzle (for K65I, K65G, K65Zh, K65K, K65P, K65R, K65S absent); 19. Rope blank; 20. Corrector-concentrator cable guide; 21. Corrector-concentrator piston; 22. Drive cable guide.

K-65 carburetors stood and at the moment also stand on different domestic-made equipment, mainly the difference in components, diffuser diameters, GTZ, ZhHKh and atomizer along with a needle.

Comparative table for the K-65 carburetor

How to properly adjust the carburetors VM 34-619 for snowmobiles: "TAYGA 550 SWT Patrul", "Taiga-Ataka 2", "TAYGA 550 SE", "Taiga-Lux 2".

The manufacturer and experts recommend that adjustments be made after the snowmobile has been run in (300 kilometers). Here the owner of the snowmobile has a choice - to give it to a service center or make adjustments on their own. Following our instructions, even a beginner will cope with this task.

1. We check the opening of the carburetor throttles for synchronism, for this you need to remove the intake silencer, take a mirror with a size of 140 by 40 millimeters and look into the carburetor diffusers while smoothly pressing the gas lever. If the chokes do not move synchronously, it is worth using the technical documentation for adjustment to adjust.

2. We look to see if there is a backlash on the sheath of the fuel corrector drive cables “should be in the closed position”.

3. We look at the position of the locks of the dosing needles of the carburetors. According to the manufacturer's recommendations: the locks of the needles should be in the middle third groove.

4. Checking the details of the dosage of carburetors:

— GTZh 230 (main fuel jet);
- ZhKhKh 55 (idle jet).

5. We look at the position of the idle mixture quality screws. To properly adjust the carburetors VM 34-619 with an idle jet 55, we recommend tightening the screws to the limit without much effort, and then turn them out two turns. For carburetors VM 34-619 with idle jet 40, we recommend to unscrew the screws by 1-1.5 turns.

6. We check the adjustments made for:

A. We clean the spark plugs from soot, set a gap of 0.7-0.8 mm.

B. Without regassing, we make a trial run of 4-6 kilometers at a speed of no more than 45-50 kilometers per hour.

C. We stop the snowmobile, turn off the engine without idling.

G. We unscrew the spark plugs and look at the color of soot. The presence of soot should be in a dark brown color.

E. If the spark plugs are spattered or there is black carbon deposits, we recommend moving the locks of the dosing needles to the upper, second groove and repeat the steps described in paragraphs A and D.

It is also possible to adjust with the idle mixture quality screws. Be careful! Do not unscrew the screws more than two and a half turns.

7. After you have completed all the steps described above, we check the operation of the engine in different modes, measure the fuel consumption. We recommend measuring fuel consumption at a speed of 40-60 kilometers per hour, taking into account one driver, without passengers.

For more accurate readings, you will need:

- Fill the snowmobile with a full gas tank, record the initial odometer data.

- Make a test run, following the odometer readings, calculate the distance traveled (S, km).

- Add gasoline from a measuring canister to the gas tank, calculate the amount of actually consumed fuel (V, l).

- Using the formula GT \u003d V / S 100 (liters / 100 km), we calculate the amount of fuel consumption by the snowmobile.

Recommendation: if your snowmobile is equipped with an RMZ-550 engine with a KOSO exhaust gas temperature sensor, it is worth checking the temperature of the engine at maximum speed, the exhaust gas temperature in the cylindrical part of the resonator can read 730-750 degrees Celsius. If the given, permissible temperature is increased, then we change the speed of movement (we release the gas).