Snowmobile Failures

During the ride, malfunctions may occur that are caused by wear and tear, improper adjustment and maintenance.

If the starter runs on the snowmobile, but the engine axis does not rotate, then there may be the following causes of the malfunction: nicks on the gear teeth, lack of engagement, slipping of the freewheel.

Eliminate nicks by refilling damaged teeth or replacing worn parts. If the coupling stalls, then it must be repaired in the workshop.

With their quick elimination, further dangerous consequences for the device will be eliminated and normal operation is guaranteed.

  1. Engine. If it does not start, then one of the reasons may be a clogging of the venting opening of the fuel tank cap. Clean this hole.
  2. Transmission. If the reverse box does not switch, then the cause may be a malfunction of the switching mechanism – adjust it.
  3. Chassis. A common symptom of a malfunction may be the play of the track roller on the shaft and its runout in the side surface. Possible causes: bearing wear or an axis shape change. To solve problems, replace the bearing, inspect the axle, and change it if necessary.
  4. Snowmobile control mechanism. Sign of breakage: tight steering. The causes of the malfunction may be jamming of the steering axle, ski pin, or malfunction of the steering gear. To solve the first problem, lubricate the bearings, for the second working surfaces.
  5. Electrical equipment. In the presence of interruptions in the ignition system, a weak spark, or the absence of a spark, a non-working candle may be a possible cause of the malfunction (it is oily, dirty). Way of elimination: clear of a deposit, wash in gasoline and wipe well. Identify and eliminate the causes of carbon deposits (incorrect composition of the combustible mixture – violation of carburetor adjustment). There may also be problems with the wire – replace it in case of breakdown.

A popular snowmobile with two tracks and ski is an indispensable tool in the household and for hobbies. Buran is highly praised by hunters, fishers, and people who live and work in harsh regions. The device is suitable for trips through the forest, in addition to household purposes, it is often used in various activities, ski training.

Thoroughly the design of the device has not changed for more than 40 years, but the manufacturer adapted it to modern requirements. The advantages are obvious: the machine is unpretentious, for a long time serves its owner.

There are features of the Buran snowmobile running gear: a small frame and a special design: “1 ski with 2 tracks” make the device a “snow bike”, which does not require much driving skill in deep snow, the machine maneuvers easily in the forest.

The vehicle has a modified hood appearance and installation pattern: the lid leans back, providing instant access to any node under the hood. To increase the convenience, the snowmobile is equipped with a modern seat with a removable backrest for passengers. The hood is made of plastic produced by injection molding: it gives resistance to environmental influences – strong impact, does not crack during frost.

Features of the device:

  • The engine RMZ-640 two-stroke and two-cylinder RMZ-640, its volume is 635 cm3, power 34 hp
  • The luggage compartment is spacious, located under a 2-seater seat.
  • The towbar is included in the basic package and provides the ability to tow a trailer weighing up to 250 kg.

Every detail has been created and implemented taking into account the main goal – safe use by customers.

Attention! Observe safety precautions. When buying a new snowmobile, it is recommended that you consult your dealer for driving and maintenance advice. The quality of this unit is ensured with regular maintenance and repair by service professionals.

The device and operation of components of Buran

Those who want to buy this car often have questions about the construction of the Russian snowmobile Buran.

It uses the following components:

  • power unit device;
  • transmission;
  • mechanisms and governing bodies;
  • housing;
  • electronic equipment.

Before starting work, it is recommended to read the instruction manual, to study in detail the design of the running gear of the Snowmobile snowmobile and the principle of operation of the units and each machine system.

Engine device

A two-stroke, two-cylinder carburetor power unit of forced air cooling is mounted on the snowmobile device. The device has a loop crank chamber purge. Familiarize yourself with the components in the drawing (Fig. 1).

Engine Elements Table

Engine Components Description
Crankshaft A crankshaft with 3 bearings is mounted on the power unit. A magdino rotor is installed on the right extreme part of the crankshaft, and a centrifugal variator regulator is installed on the left.
Shatun In each hole of the heads (upper and lower) of the connecting rod 12, needle bearings of different sizes are mounted: 16 and 9. Radial clearance in the range from 0.012 to 0.024 mm. The gap can be ensured by sorting by size into size groups of bearing rollers, as well as piston and crank fingers, which correspond to the holes of the connecting rods. The holes are marked on the rod under all heads.
Piston ring Two rings 17 are mounted on the pistons. The lock includes a thermal gap. After installing the rings in the cylinder (CL) of the motor, the clearance should be within 0.25 mm (not less). To get the indicated gaps, you can file the ends of the castle. The gap between the ends of the ring and the ditches during compression should leave up to 0.115 mm.
Piston There are pistons on the motor: left 19 and right 22. The element is installed in the central unit with a gap that is 0.16 mm between the piston skirt and the central unit. When the engine overheats, the piston will jam in the cylinder. There are 3 groups of pistons: M, C, B (smallest, medium and largest). The designation of the group with dimensions is printed on the inner belt of the piston skirt.
Piston pin During assembly, the piston pins are sorted into 2 groups by their outer diameter. The group is marked with light or dark colors of paint on the end of the finger. In the assembly process, a finger with a piston is selected in the 1st group.
Cylinder head Two heads TsL sizes 20 and 23 are made of Al alloy. To prevent changes in the structure of the head and cylinder, the stud nuts should be tightened crosswise in 2 steps: first, preliminary, and then finally with a tightening of up to 2.5 kgf / m. The collector nuts must be tightened first. Tighten them on an unheated power unit.
Cylinder 13 and 21 of the CL are not interchangeable. To ensure selective assembly of the sleeve-piston pair, the cylinders are manufactured in 3 dimensional groups. Dimensional groups are marked with the letters: M, C, B and the shock method is applied to the belt of the lower cylinder flange. When changing the CL, a new corresponding group must be installed. The CL is mounted on the crankcase of the motor, the head is installed on the top. Between the head and the cylinder there is a gasket 18. There is also a gasket 11 located in the center between the flange and the supporting plane.
Carter This part consists of 2 halves. They are connected by spiers screwed into its upper part; fastening nuts are tightened with a moment of 3 kgf / m. For tightness under the heads of the bolts 73 screwed into these products, copper gaskets are mounted.
Engine cooling When the motor is turned on, the temperature should be up to 200 ° C. To maintain the motor temperature within normal limits, the use of an air cooling system is required, including an axial discharge fan and additional blower housings.

The basis of the fan is the impeller 24, which is launched by the V-belt 30 from the drive pulley 36 mounted on the flywheel rotor. At the end of the impeller roller there is a driven pulley, including two half-pulley disks 29. The fastening nut is tightened with a moment of 5 kgf⋅m. The fan inlet has an air intake 31.

The figure shows the details of the power unit device, about which it was described above.

Fig. 1 – Engine

Attention! When you turn on the power unit, you sometimes need to check the quality of the fan belt tension. If it is weak, then the belt slipping effect at high speeds is possible, its stratification from heating. If the tension is strong, the impeller bearings break. If grease enters the belt, it may be destroyed. Do not allow this and replace the part in time.

The Buran engine is equipped with a mechanical device, in addition to the Buran 4T, 4TD, on other models an electric starter is installed. Manual mounted on the fan case with 4 fans. A starter pulley with ratchet elements is located in the hull. The return spring is made spiral, its ends are curved. The outer end of the spring is fixed to the cast indentation of the pulley, the inner end is attached to the protrusion.

For reference: if the manual starter fails, there is the possibility of an emergency start of the motor. Carry out it according to instructions of the operation manual, subsection 3.3.

Appointments of other components designed for the operation of the motor and its control:

  1. Supply system.
  2. Fuel tank.
  3. Sump filter.
  4. Hand pump.
  5. Air cleaner
  6. Carburetor.
  7. Fuel pump.
  8. Exhaust system.
  9. Powertrain suspension. The elastic bearings of this part of the motor consist of rubberized shock absorbers, which are put on the nuts. The latter are mounted on bolts that are inserted into the holes of the frame.

The motor is mounted to the base with 4 bolts. To adjust the distance between the variator pulleys, rings are installed.

Fig. 1a – Suspension of the power unit Buran

On the Buran frame, an engine with an engine mount is fixed at 4 points. The elastic suspension reduces the transmission of vibration, a functioning motor to the frame, and the shocks that appear during movement.

Transmission (Drive)

The transmission of the running gear of the Buran snowmobile consists of two elements: a V-belt type of the variator and a chain-type reverse box. The variator (Fig. 2) is a V-belt drive with automatic change in the functional properties of the pulleys (main and driven) through a centrifugal regulator when changing the speed of the motor and cam clutch when changing the resistance to movement of the apparatus.

The main parts of the variator: a driving friction wheel with a rim (pulley) with a centrifugal regulator, which is mounted on the axis of the motor, and driven with a cam clutch on the head shaft of the reverse box, as well as a belt.

Driven friction wheel with rim includes:

  • fixed disk (ND) 21;
  • mobile (PD) 1;
  • return spring type 22;
  • half coupling (PF) 3.

The last part of the driven pulley is held on the axis from the rotation by the key 2. During the operation of the variator, the 5 PF liners move along the top of the PD screw. The spring is between two parts – the coupling half and the PD, and it has a preliminary preload and a twist of 120 degrees. The split ring (PK) 28, which is installed on the axis by the spring ring 29, is a restrictive part, namely it stops the movement of the PD to the ND and is simultaneously an emphasis for a stationary spring ring (PC) 29 mounted on the axis, and a stop for the ND mounted on the shaft with a key 23, a washer (W) 26, a lock 25, a bolt 24. Between parts 28 and 21 there are adjusting rings 27 to obtain the desired size of the driven pulley. There are 3 threaded holes for dismantling the ID.

Fig. 2 – CVT

Fig.3a – reverse box

The reverse box (CR) of the snowmobile is designed to transmit torque from the main shaft to the axes of the main track sprockets, to move backward and to disconnect the motor from the chassis.

The box (Fig. 3a) includes the shafts: the drive shaft, for starting the reverse, the gear and chain transmission, which includes the forward and reverse gears, as well as the follower, the chain tensioning mechanism and the drive chain (98 links in total).

The control of the control gear is carried out manually, that is, with a drive that consists of a shift handle and a rod connecting the handle with the mechanism lever.


Consists of caterpillar and ski. We will analyze their structure in more detail:

  1. The caterpillar mover contains caterpillars, axles of the guiding and leading type with stars and balancers of the rollers. Caterpillars are installed so that the right angle of the lugs is directed forward, because they crush the snow under themselves, without capturing it.
  2. Steel brackets mounted between the windows are designed for precise engagement of head teeth and guide sprockets. Driving with dropped brackets leads to rapid wear of teeth and tracks due to damage and rupture of jumpers between windows.

Fig. 4 – The leading axis of the tracks

The driving axis (Fig. 4) is located in front of the machine frame and includes a steel hollow shaft 5 with attached hubs 4, 2 and sprockets mounted between them 3. Each of them can be attached to the hubs with bolts and nuts. At the ends of the shaft there are bearings 10 and cuffs 9. Between the shaft support and the cuff, the circlip 13.

Fig. 5 – Guide shaft

The guide shaft (Fig. 5) contains a full shaft 23 with hubs 22, 17 attached to it, which are placed between the parts of the sprockets 19, bearings and cuffs: the locking ring 12 and the washer 11 are located between the cuff and the bearing.

The axle bearings are lubricated during assembly of the component and during maintenance through an opening in the cheek of the balancer, which is closed by a plug 13. The guide shaft is placed in an important part of the frame on the balancers 24.

Other chassis components:

  1. Ski and its suspension. The steering ski is made of steel, it is stamped. At the bottom of the ski mounted skid 16, which protects it from wear.
  2. Steering. It consists of other components: steering column, pivot arm, king pin, shock absorber.

The steering column is installed through bushings that perform the action of sliding bearings, to the rack and box brackets with special covers 13. The steering wheel is connected by a cover and bolts to the body of the column.


It is the basis for the installation of each mechanism and assembly.

The main components of the case:

  • frame;
  • casing;
  • seat;
  • hood;
  • dashboard.

Bearing frame, it is rigid and welded. Frame elements are made of steel sheet. The rigidity of the structure is provided by a frame of corners and pipes. The frame is made of pipes, the fiberglass hood closes the compartment, consisting of a motor and transmission. From the side where the seat is located, the engine is covered by a casing and an instrument panel. Instruments and an element of the apparatus controls are installed on it. The folding seat, designed for 2 seats, is located on the frame on hinges of hinge type.

In the rear half of the frame is a cargo area. At the request of the consumer, Buran brand snowmobiles are additionally equipped with a ski kit.

Control mechanisms and devices

The arrangement of control devices is shown in fig. 6.

Drawing. 6 – Controls

The brake lever is located on the left of the steering wheel. When the lever is pressed, the brake mechanism is activated, and when released, the lever automatically returns to its original state. Slowing down the snowmobile will depend on the quality of the snow cover.

Attention! Fast and frequent braking of a vehicle moving at high speed can cause the brake mechanism to overheat – this leads to a significant decrease in braking performance.

Brake light switch for hand brake. When the brake lever is activated, the rod closes the contacts, while the stop lamp is turned on, which is installed in the rear lamp. After releasing the lever, the switch rod completely opens the contacts, while the lamp goes out.

Other controls and mechanisms:

  • light switch;
  • gas lever heater element switch (VNRG);
  • ignition switch (VZ);
  • oil indicator (MI);
  • emergency switch (AB);
  • speedometer;
  • gas lever;
  • parking brake limiter;
  • steering wheel;
  • egnition lock;
  • starter and gear shift knobs;
  • levers of fuel corrector carburetor devices;
  • daily counter reset knob;
  • pump handle;
  • floodlight switch (optional):
  • socket (optional):
  • carburetor control element drive.

Attention! The brake must be locked when the reverse gear is engaged.

Electrical equipment

The snowmobile device uses a combined system of electronic equipment (EA) with a voltage of 12 V; one wire for the rear light, for the other EO – two wires.

A non-contact electronic ignition system is created by different manufacturers:

  • FSUE “UAPO”, Ufa;
  • Flames Company LLC, Moscow.

The ignition system should only be placed on vehicles in sets; when using a separate element of the ignition system (except for the flywheel device), engine damage may occur.

Other elements of electrical equipment:

  • stator;
  • founding parsley;
  • rotor;
  • ignition coil;
  • switch;
  • candle tip;
  • candle;
  • electric starter;
  • starter relay;
  • rear lamp;
  • fuse;
  • lighthouse;
  • stop lamp switch;
  • voltage regulator;
  • battery;
  • electronic wiring;
  • electronic plug connectors.

On some modifications of Buran, a system with an electric unit is installed, which, when receiving information from sensors located on the motor, controls the nozzles and coils of the ignition system.

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