DIY snowmobile repair Buran 640

The RMZ-640 "Buran" engine produced by the Rybinsk Motor-Building Plant is widely used not only on the snowmobiles of the same name, but also on deltalets. However, if individual snowmobile owners are satisfied with its characteristics to some extent, then pilots - with rare exceptions. And many of those who deal with RMZ for a long time are aware of the constant threat of cylinder overheating and piston burnout. Therefore, delta pilots are trying to replace the "six hundred and forty" engine with a better one, if possible with an imported one, or, at worst, improve it.

In general, they have few ways of improvement: either to improve the existing structure in detail, or to remodel it on a large scale. The most decisive go for a deep modernization, affecting the main systems of the Rybinsk motor. Regular readers of our magazine know examples of such modernization. The most famous, dating back to the fall of 1996, is given in the publications "Beetle-42: Transport for Heaven and Earth" (Modelist-Constructor No. 8,9,11 ’96). Anatoly Zhukov, the designer of the Zhuk deltaplane, increased the power of the 600th by equipping its cylinders with individual carburetors and mufflers. He solved the temperature problem radically by converting the engine from air to liquid cooling.

However, the reserves of the standard RMZ-640 are far from being exhausted. Many designers are engaged in the opening of these reserves: in Rybinsk, in the factory design bureau, and in other cities, in flying clubs, various laboratories and scientific and technical centers. Valery NOVOSELTSEV, an employee of the Moscow Scientific and Technical Center “Istok”, presents his version of improving the performance of the famous engine.

The article describes the work on the modernization of the RMZ-640 "Buran". The participants set themselves the task of improving the performance of a widely used engine. One of the main activities to accomplish this task was to refine the design of plate check valves.

In our case, we used a serial engine with serial number 88410219, which had previously worked on a two-seat deltaplane for 46 hours. The declared power of this engine is 28 hp. at 5500 rpm. It is equipped with a V-belt reducer with a gear ratio of 1: 2.15, a propeller with a diameter of 1.6 m and a pitch of 0.79 m, as well as standard A17DV candles and a K-62Zh carburetor with a diffuser diameter of 32 mm and a main jet with a diameter of 1.36 mm.

The engine ran on fuel consisting of a mixture of AI-93 gasoline (specific gravity 0.74) and MGD-14M oil in a ratio of 1:30. Fuel was supplied by gravity from a supply tank installed at a height of 2.5 m relative to the carburetor.

Before the tests, the valve timing was checked, the effective compression ratio was refined - it was Eef = 5.6. A low value of the average effective pressure of the serial engine was noted - only 3.56 kg / cm2.

All operations related to the removal of characteristics were carried out on a complex engine test bench made in the aviation department of the Scientific and Technical Center "Istok" and which made it possible to simultaneously register the values ​​of torque, fuel consumption, speed and temperature of the cylinder heads.

The stand includes a balancing machine, a moulinette (wooden propeller with a diameter of 840 mm), a fuel flow meter (shtihprober) with hermetically sealed contacts (reed switches), a thermocouple with a dial indicator, and a fuel tank with a capacity of 10 liters.

To change the moment of resistance, six pairs of replaceable brake plates were attached to the ends of the moulinette blades, which made it possible to obtain seven points for measuring the parameters of the external characteristic.

The measuring base of the gauge consisted of three volumes controlled by reed switches, a magnetic float and three-way valves. Electronic tachometer - contactless, with an induction sensor. Temperature meter - aviation, registering the temperature of the cylinder heads under the spark plug.

To reduce frictional forces, all movable joints of the machine are equipped with rolling bearings.

The work was carried out in four stages:

1) taking the initial (control) characteristics of the serial engine;

3) taking the characteristics of the upgraded engine and checking it over on a hang-glider;

4) taking the characteristics of the upgraded engine without a blower and gearbox.

The first stage was carried out on a complex motor test bench.

Rice. 1. Units and parts of the serial engine RMZ-640 "Buran", which were re-manufactured or modernized.

Rice. 2. Modified inlet (a) and outlet (b) cylinder windows (the cylinder surface is deployed in the plane of the drawing).

Rice. 3. Modified piston (the surface of the piston is deployed in the plane of the drawing).

Rice. 4. Displacers in the crankcase:

1 - crank chamber; 2 - displacers (AMg-6); 3 - screw M4 (20 pcs.).

Rice. 5. Displacers on the crankshaft:

1 - crankshaft; 2 - displacers (glass fiber on epoxy binder); 3 - holes (drilling d4 to a depth of 0.5 mm, 20 pcs.).

Rice. 6. Block of cuffs:

1 - clip (anodized D16T); 2 - sealing ring, rubber (from VAZ-2108); 3 - cuff (from VAZ-2101, cut off).

Rice. 7. Valve box:

1 - plate valve (2 pcs.); 2 - box body (AL1); 3 - cover (AL1); 4 - screw M5 (8 pcs.).

Test conditions: outside air temperature + 2 ° С; atmospheric pressure - 746 mm Hg; fuel - a mixture of AI-93 gasoline with MGD-14M oil (1:30); carburetor - К-62Ж (main jet diameter - 1.36 mm; effective compression ratio Eef = 5.6); candles - А17ДВ.

The following results were obtained.

Propeller characteristic (external load - propeller with a diameter

1.6 m at 0.79 m steps): Ne = 25.8 HP at 5086 rpm, Ce = 0.433 kg / h HP

External characteristic (external load - moulinette): Ne = 27.9 HP at 5514 rpm, Ce = 0.416 kg / h HP Head temperature t ° C = 212 ° C.

The second stage is the actual modernization. Have undergone revision; crankcase (displacers are installed in the corners of the crank chamber), cylinder heads (the bearing surfaces of the heads are cut by

1.8 mm to increase the effective compression ratio, Eef increased to 7.2, the cylinders themselves (the intake and exhaust ports are bored), the crankshaft (displacers are installed in the cheek grooves), the cuffs of the crankshaft main journals (cut by 1 mm). The carburetor diffuser was also bored to a diameter of 33.6 mm, the diameter of the main jet was increased to 2.12 mm, and the height of the nozzle was reduced by 0.76 mm.

The valve timing (intake and exhaust) is increased. Each cylinder has two additional bypass channels with phases equal to the phases of the main channels (the cylinder liner was not pressed out in this case).

Made anew; pistons, valve box, box cover, plate check valves (plates, seats and stops), cuff clips.

The pistons are forged from AK12D alloy. They have two purge ports each, which lowered the temperature of the upper rings and piston heads and excluded burnout.

Unlike the serial piston, the skirt of the new piston is barrel-shaped and elliptical in accordance with the temperature gradient. The geometry of the skirt was adjusted experimentally. Since this process is rather complicated, it is possible to leave the standard pistons as well, modifying them according to the attached drawings.

The body and cover of the box of plate check valves are cast from АЛ1. However, it is possible to use any other cast heat-treatable aluminum alloy.

The valve seats are made by pressing from organite (or Kevlar, as this SVM is also called - ultra-high-strength material) on an epoxy binder heated to 80-85 ° C during the polymerization process. Saddle sizes with minor changes are taken from the book by V.M. Kondrashev and others (see Literature).The material of the valve plates is STEF-1 fiberglass, the stoppers are steel.

Since the placement of the valves and the bore of the cylinder windows increase the volume of the crankcase by 41 cm3 (which leads to a decrease in the purge pressure and, as a result, to a decrease in the maximum engine power), so-called displacers are installed in the grooves of the crankshaft cheeks and in the corners of the crankcase harmful volume. On the crankshaft, they are made of glass thread on an epoxy binder (for better adhesion of the winding to the cheeks with a drill with a diameter of 4 mm, holes with a depth of 0.5 mm are marked in them). In the crankcase, the displacers are aluminum half-rings of triangular cross-section, fastened with M4 screws.

The sum of the displaced volume in the chamber together with the volume displaced by the cuff yoke is 79 cm3, which more than compensates for the increase in volume from valve placement and window boring, which ultimately improves blowdown.

However, the increase in pressure in the crankcase led to the fact that the standard cuffs began to be squeezed out of the clips. This was revealed during the first engine starts. I had to make new clips and install in them cuffs from the axle shafts of the VAZ-2101 car, cut by 1 mm and facing each other with the front side. To seal the clips, rubber rings from the ignition shaft from the engine of a VAZ-2108 car were used.

Rice. 8. Plate valve:

1 - valve seat (organotili kevlar); 2 - M3 bolt (4 pcs.); 3 stopper (steel, 2 pcs.); 4 valve plate (fiberglass STEF-1, 2 pcs.).

Before mounting the cuffs, the clips were heated to 200-250 ° C. Then, TsIATIM-201 grease with molybdenum disulfite was stuffed in the cuff cavity, after which the clips were mounted on the crankshaft. Their shoulders are tucked into the crankcase recesses, and the standard thrust rings are dismantled.

In addition to these works, the usual two-stroke ICE procedures were carried out to refine the inner surfaces, that is, cleaning the casting in channels and windows and adjusting the mating lines of the crankcase and cylinders. More about this in the book of IM Grigoriev (see Literature).

Stage three. During repeated tests, the parameters of the external, screw, flow characteristics and the maximum temperature of the cylinder head under the spark plug were measured. The temperature and composition of the exhaust gases were not indicated. The power was brought back to normal conditions. The ignition system has not been changed or adjusted.

Test conditions: outside air temperature - 8 ° С; atmospheric pressure - 748 mm Hg; fuel and external load are the same as before the upgrade; the carburetor diffuser is bored to a diameter of 33.6 mm; main jet - up to a diameter of 2.12 mm; Eef = 7.2.

Results of tests of the upgraded engine.

Propeller characteristic: Ne = 31.7 h.p. at 5316 rpm, Ce = 0.321 kg / h HP; head temperature t ° Cmax = 204 ° C; increase in capacity - 22.8 percent, efficiency - 25.8 percent.

External characteristic: Ne = 38.2 hp at 5778 rpm, Ce = 0.332 kg / h HP Head temperature - t ° Сmax = 208 ° С; increase in capacity - 36.9 percent, efficiency - 20.25 percent.

And finally, the fourth stage. In the configuration without a gearbox and a blower, the engine spun up to 6840 rpm, the recorded power was 19.6 hp, Ce = 42.2 hp. at 5978 rpm, Ce = 0.338 kg / h HP

For the characteristics of the modernized engine, a new propeller with a Wortman profile RH-63-137 with a diameter of 1.6 m and a pitch of 0.8 m was designed and manufactured for a flight speed of 72 km / h. With him on the mooring lines, a thrust of 152 kg was obtained. Prior to this, the thrust on the mooring serial engine with a standard propeller reached 112 kg, after modernization - 135 kg.

The rate of climb of a two-seater hang-glider with a serial engine and a standard propeller was 1 m / s. After modernization, with the same propeller, - 2.5-2.8 m / s; and with the newly manufactured - 3-3.2 m / s, while the hourly fuel consumption did not exceed 9 liters.

The temperature of the head of the "hot" cylinder of the modernized engine during take-off and climb operation at an outside air temperature of + 28 ° C did not exceed 195 ° C.

Bottom line: after completing the listed stages of modernization, the engine's operation became smoother and smoother, starting was much easier. Almost all of its main characteristics have improved: power, efficiency, continuity and, most importantly, reliability. At the end of September 1999, the engine worked 32 hours in deltaplane flights without any remarks.

V. NOVOSELTSEV

1. Kondrashev V.M., Grigoriev Yu.S., Tupov V.V., Sillat P.P., Abramov V.I., Strokin A.N. Two-stroke carburetor internal combustion engines. - M., mechanical engineering, 1990.

2. Grigoriev I.M. A motorcycle without secrets. - M., DOSAAF, 1973.

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Took the following
1. I made grooves in the pistons in the part of the groove for a specific thickness of the rings
2. Changed the geometry of the chamfers, now the protruding part locks the ring in the groove and when the chamfer presses it simply has nowhere to go
3. On the insistent advice of a member of the forum (Dad) cut the retaining rings upward, it is possible and downward only supposedly not from the side. The logic seems to be seen on the basis of shock loads

These improvements will in no way go to a minus, only to a plus, and what a plus will winter show

Pistons "Almet" Czech
production is applied with rings
14-076-15-07
"Buzuluk" Czech production.
two-channel purge - gaskets under the cylinder 110500103
cylinders with four-channel purge (both) are installed on a universal crankcase with gaskets under the cylinder 110501192

The pistons fit any cylinder.

Re: ICE RMZ "Buran" - repair, revision, reviews.

Pordonyu, of course, but I thought this site is about a boat theme and the consequences from here.
There is a forum specially created for this.
There is a huge amount of information on "Burashka". There are answers to all questions!)))
There is also about boats of course, but for some reason I went here, here is more information.
On the snow site I am registered as “Kuzmich84”, although I have already switched from the “Buran” branch to the “Taiga 550 V” branch, but only positive emotions remain about “Burashka”!))

Re: ICE RMZ "Buran" - repair, revision, reviews.

It is interesting to collect everything in one place, I will share my experience

Complete disassembly, chamfering on the piston rings to reduce the friction surface, raising the exhaust ports by 2 mm - but this point is controversial about the increase in power, because engines work without changing channels;
removed the native gasket under the head, replaced it with an aluminum ring from the Dnieper; balancing pistons to a difference of less than 1.5 grams;
production of oil channels for lubrication of thrust bearings, as described in the article "Model Designer", removed 1.5 mm from the outer cage of the thrust bearing from the side of the crankshaft cheeks, for better lubricant passage through the gap. I removed the gasket under the sleeve, put a new one out of plain paper, smearing it with sealant.
For an engine with two-channel purge, I think there is no point in installing two carburetors, because the cross-section on the bypass is already small.
The factor of setting up the engine with the device is also important, since even a difference of one division on the carburetor needle gives a temperature difference of the order of 30 degrees.
I redid the cooling system - I closed the rear window and made the windows on the side like on a rotax. In the photo you can see
All this was done in order to improve reliability, since initially there was a problem with overheating.
And another important factor - I removed all the electrics: coils, a commutator on the trike frame, so that it would ruin less.

The carburetor supplied “Pekar” for the Planet, there the jets are the largest, installed an enricher, with it starting from the first, maximum of the second jerk. There was an overflow problem at certain speeds. I made a return flow - after the pump I installed a tee and a check valve from the eight Zhiguli, I put a filter in front of the carburetor, it is placed in such a way that it excludes the formation of foam from the vibration of the filter, it is also a kind of storage tank. The first filter is small, installed right after the tank.It turns out that gasoline is cleaned in front of the pump, the excess goes into the tank, and the flow is constant, it is cleaned a second time when it enters the carb. The constant movement of the fuel through the pump cools the latter well.

The photo is old, the switch was still on the motor

Recently I fixed the coils on the base of the Magdino epoxy, because they sit very badly on the cores and over time they begin to dangle, there are ignition interruptions.

Dad-60 04 Feb 2012, 19:09

Andrey 051 »04 Feb 2012, 21:40

Filipych »17 Feb 2012, 14:02

A Murmansk resident wrote: the miracle of our blizzard industry, that's what he found.
Snowmobile "Buran" with your own hands.
Assemble the Buran snowmobile yourself
We offer you a complete set of parts and assemblies for self-assembly of the Buran snowmobile. The set includes all even small parts and fasteners. With only a set of wrenches in your arsenal, you can assemble a snowmobile that is superior in quality to the most demanded Russian-made snowmobile. The main advantages of a snowmobile assembled from the proposed kit-kit:
- more high-torque and economical 4-stroke engine of "Honda" design, manufactured in China, modified by our company;
- Reinforced frame produced by Buran-chassis;
- lower cost in comparison with the original.
Moreover, all parts, except for the engine, are completely interchangeable with the parts of the Buran snowmobile, which makes it maintainable in any region of Russia.

We are ready to send the Buran snowmobile kit by a transport company to any region of the country.

The price of the Buran snowmobile kit is 158,000 rubles

And the revision of the "dvigi" probably consists of replacing pistons from birch to pine, aluminum connecting rods (Russian recyclable materials - to China.) And lead bearings. The life of this miracle is 300 km, in the most successful case.
Have already seen: NAH.

Filipych »17 Feb 2012, 14:20

Assenny »26 Feb 2012, 00:40

Mikhail, I am very glad for you that I have installed the heating of the handles and the trigger! And our hands are freezing! Please explain: What pens, where did you get it, how did you connect it? But no, this is a question for Buranovod.

Filipych Apr 29, 2012 6:54 pm

Dad-60 »Apr 30, 2012 7:35 am

Dyuk »01 May 2012, 11:12

Yuri Timofeevich is right. The treated pistons and cylinders did not even show any signs of wedging this year, although we drove the technique to the fullest as usual.
As for the modifications to the exhaust system, everything is also correct. an exhaust system with a DD resonator gives an increase of about 30%, i.e. about 43 hp removed from the engine. there are two sound options, 4 decibels quieter (about 25%) on the driver's side and 43 hp. removed from the engine and 6 decibels quieter (about half) on the driver's side and 38 hp. remove from the engine.
Consumption drops by about 15%. The other's engine becomes with this system.
Well, and the fact that they ask to write to your personal mail, what's so strange about that? We do not like people who develop skills and realize the fruits of their labor.
Write to Yuri Timofeevich (Dad-60), he will always help.

Filipych »01 May 2012, 19:15

Filipych »01 May 2012, 19:25

Dad-60 »03 May 2012, 07:02

Filipych »03 May 2012, 22:06

Andreich »04 June 2012, 12:39

Andreich »05 June 2012, 05:32

Andreich »05 June 2012, 05:46

Andreich »06 Jun 2012, 07:08

Andreich »06 June 2012, 07:20

Andreich »19 June 2012, 11:14

Assenny »29 Jul 2012, 21:45

Hermann »04 Aug 2012, 05:28

He's set on hot. It is advisable to remove it with a native puller, which is screwed onto the thread of the flywheel, then squeezed out with a bolt, you can heat it up a little, but you can break it by the edges. Then I look at your old wiring and there is a VSA. change all the wiring to normal, and connect from the magneto to a straight line, bypassing all the crap, and take off the starter, if you don't use it, when replacing the shaft, you can not put the crown later, if, again, you do not use a starter and accumulators, I have not had it for a long time.

Filipych »05 Aug 2012, 05:21

aleks66 »11 Aug 2012, 06:57

aleks66 »11 Aug 2012, 07:07

Mishel1 »13 Aug 2012, 09:33

Starower »16 Nov 2012, 18:16

Starower »16 Nov 2012, 18:39

Mishel1 »16 Nov 2012, 20:01

Starower »20 Nov 2012, 18:08

Starower »20 Nov 2012, 18:33

finally I collected everything and when I looked around and saw that there was still a casing for the variatar. I thought I'd put it on, but I couldn't, the resonator interfered, I didn't want to take it off. I decided to leave the casing alone for now.
Moreover, on the advice I soldered a resistor into one of the wires of the button to turn off the engine.The blizzard started up hard, felt its overflow with fuel, raised the needle one notch and began to wind up and work normally. But I will not say anything about everything else - I don’t know. The engine sound became quieter. I want to fill up a full tank and check how long it will last. I'll unsubscribe later. Till.

Hermann »21 Nov 2012, 03:03

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Took the following
1. I made grooves in the pistons in the part of the groove for a specific thickness of the rings
2. Changed the geometry of the chamfers, now the protruding part locks the ring in the groove and when the chamfer presses it simply has nowhere to go
3. On the insistent advice of a member of the forum (Dad) cut the retaining rings upward, it is possible and downward only supposedly not from the side. The logic seems to be seen on the basis of shock loads

These improvements will in no way go to a minus, only to a plus, and what a plus will winter show

Pistons "Almet" Czech
production is applied with rings
14-076-15-07
"Buzuluk" Czech production.
two-channel purge - gaskets under the cylinder 110500103
cylinders with four-channel purge (both) are installed on a universal crankcase with gaskets under the cylinder 110501192

The pistons fit any cylinder.

The snowmobile is equipped with a two-cylinder, two-stroke with loop crank-chamber blowing, carburetor engine RMZ-640-34 forced air cooling (Fig. 2).

Crankshaft. The engine has a three-bearing crankshaft. At the right end of the crankshaft there is a magdino rotor (flywheel), on the left - a variator centrifugal regulator.

Connecting rod. Needle bearings 16 and 9 are installed in the holes of the upper and lower heads of the connecting rod 12. The radial clearance in the bearings of the upper and lower heads is 0.012. 0.024 mm. The specified clearance is provided by sorting by diameter into the size groups of bearing rollers, piston and crank pins, corresponding to the connecting rod bores. The connecting rod hole group is marked on the rod under each head.

The piston is installed in the cylinder with a clearance. The clearance between the piston skirt and the cylinder on a cold engine is 0.14. 0.16 mm. If the engine overheats, the piston can jam in the cylinder.

To ensure the selection of the liners, the pistons are produced in three size groups: M, C, B (small, medium, large). The size group is marked on the inner shoulder of the piston skirt. According to the diameter of the hole for the piston pin, the pistons are sorted into two size groups; the group is marked with white or black paints. When changing a piston, the piston of the corresponding group must be installed.

Piston ring. Two piston rings 17 are installed on the pistons. A thermal gap is provided in the ring lock. After installing the rings in the engine cylinder, the clearance should be 0.25 ... 0.45 mm. To obtain the indicated gaps, filing of the ends of the lock is allowed.

The gap between the ends of the ring and the grooves when the ring is compressed to a diameter of 76 mm should be 0.080 ... 0.115 mm.

Piston pin. During assembly, the piston pins are sorted by outer diameter into two size groups. The group is marked with white or black paint on the end of the finger. When assembling, the finger with the piston is selected from one group.

Cylinder. Installed on the engine, the left 13 and right 21 cylinders are not interchangeable with each other. To ensure selective assembly of the liner-piston interface, the cylinders are available in three size groups. Dimensional groups are designated by letters: M, C, B and are strikingly applied on the girdle of the lower flange of the cylinder.When changing a cylinder, it is necessary to install the cylinder of the corresponding group.

The cylinder is mounted on the bottom flange on the engine crankcase, on the top flange the cylinder head is placed. An asbestos gasket 18 is installed between the head and the cylinder.

the masonry can be reused. A paronite gasket 11 is installed between the lower flange of the cylinder and the bearing plane of the crankcase.

Cylinder head. The left 20 and right 23 cylinder heads are made of aluminum alloy. In order to avoid unacceptable deformation of the head and cylinder during assembly, the stud nuts are tightened crosswise in two steps: first, preliminary, and then finally, with a tightening torque of 2.0. 2.5 kgf  m. In this case, the intake manifold retaining nuts must be tightened first. Tighten or tighten the nuts on a cold engine.

Carter consists of two halves. The halves of the crankcase are interconnected by pins screwed into its upper half; the nuts securing the crankcase halves are tightened to a torque of 3.0. 3.5 kgf  m. The crankcase halves are processed together and therefore are not interchangeable. Each cylinder with a head is attached to the crankcase with four pins.

On the flange on the right side of the crankcase, the base of the magdino and the fan housing are installed. The fuel pump is fixed on the high tide in the upper part of the crankcase with two screws and a fitting for the pulsation supply tube is installed. On snowmobiles equipped with an electric start system, there is a lug with two studs for attaching the electric starter bracket to the rear of the crankcase. Four studs screwed into the lower half of the crankcase are used to secure the engine to the sub-base. Two threaded holes are intended for draining oil and fuel when de-preserving the engine and flushing the crankcase. To ensure tightness under the heads of the bolts 73, screwed into these holes, copper gaskets are installed.

Engine cooling. When the engine is running, the head temperature should not exceed 200 ° C. To maintain the temperature of the engine within the limits ensuring its normal operation in all operating conditions, an air cooling system is used, which includes an axial blower fan and blower shrouds.

The base of the fan is an impeller 24, which is driven by a V-belt 30 from a drive pulley 36 mounted on the magdino rotor. At the end of the impeller roller, there is a driven pulley consisting of two half-sheave disks 29. The pulley fastening nut is tightened to a torque of 5.6 kgf  m. A plastic air intake 31 is installed at the fan inlet.

1 - engine base; 2 - the lower half of the crankcase; 3 - left pivot; 4 - bearing; 5 - cuff; 6 - amortization ring; 7 - retaining ring; 8 - cheek; 9 - needle bearing; 10 - the upper half of the crankcase; 11 - gasket; 12 - connecting rod; 13 - left cylinder; 14 - piston pin; 15 - retaining ring; 16 - needle bearing; 17 - piston ring; 18 - gasket; 19 - left piston; 20 - left cylinder head; 21 - right cylinder; 22 - right piston; 23 - right cylinder head; 24 - fan impeller; 25 - bearing; 26 - adjusting ring; 27 - retaining ring; 28 - fan case; 29 - driven pulley; 30 - fan belt; 31 - air intake; 32 - adjusting washer; 33 - segmented key; 34 - nut;

35 - fan roller; 36 - driving pulley; 37 - segmented key; 38 - manual starter; 39 - bolt; 40 - nut; 41 - hairpin; 42 - magdino rotor; 43 - magdino stator; 44 - hairpin; 45 - nut; 46 - right pivot; 47 - sealing ring; 48 - labyrinth; 49 - medium shaft; 50 - nut; 51 - electric starter; 52 - nut;

53 - hairpin; 54 - exhaust manifold; 55 - hairpin; 56 - nut; 57 - gasket; 58 - nut; 59 - hairpin; 60 - spark plug; 61 - intake manifold; 62 - sealing ring; 63 - adapter; 64 - nut; 65 - hairpin; 66 - car-

bureaucrat; 67 - hairpin; 68 - nut; 69 - air cleaner; 70 - screw; 71 - fuel pump; 72 - fuel pipe; 73 - bolt (plug); 74 - bushing; 75 - washer; 76 - nut; 77 - hairpin; 78 - gear

The belt is tensioned by shifting the adjusting washers 32, located between the half-pulleys, to the outer side of the rear half-pulley. When operating the engine, a period of

Check the tension of the fan belt. Too little tension causes the belt to slip at high engine speeds and stratification from heating; a strong tension destroys the impeller bearings. Do not get grease on the belt, as it causes its destruction and slipping.

Starting system. The snowmobile engine is equipped with a mechanical starting device (manual starter), except for BURAN 4T, 4TD. An electric starter is installed on the AE, ATE, ADE, ADTE, LE, LDE, 4T and 4TD trim levels.

The recoil starter is fixed to the fan housing with four screws. The housing houses a starter pulley with ratchet parts. The recoil spring of the pulley is made spiral, its ends are bent. The outer end of the spring is engaged with the cast lug of the pulley, the inner

- for the protrusion of the body. If you look at the pulley from the side of the spring, then the winding of the spring should be directed counterclockwise, the winding of the cable - clockwise.

In case of failure of the recoil starter, the engine can be started in an emergency. Start the engine from the emergency system in accordance with the instructions in subsection 3.3 “Starting and stopping the engine”.

The engine power system includes a fuel tank with a suction filter in the tank, a sump filter, a manual booster pump, a carburetor, a fuel pump, an air cleaner (or intake silencer), and fuel lines.

The fuel tank is installed at the front of the frame. The filler neck of the tank is closed with a lid. The venting hole in the lid prevents the formation of a vacuum in the tank as fuel is consumed. The hole in the top of the tank is for the fuel intake. A fuel filter is installed at the end of the intake tube. The hole on the right side of the tank, hermetically sealed with a plug, is a technological one. There is a hatch with a cover for access to the filler neck in the bonnet.

The fuel line consists of rubber and polyurethane pipes connecting the fuel tank to the carburetor.

The manual priming pump is designed to fill the fuel system immediately before starting the engine. The use of manual fuel priming greatly facilitates starting a cold engine at low temperatures.

The snowmobile is equipped with a piston-type booster pump, which is attached to the dashboard. To fill the fuel system, the pump handle must be pulled out and depressed several times.

The air cleaner is designed to clean the air entering the carburetor. The air cleaner is attached to the carburetor with two springs.

Carburetor is intended for preparation of a fuel-air mixture for the engine. Carburetor MIKUNI VM34-619 - single-chamber with a central location of the float chamber and a cylindrical throttle of vertical travel.

The MIKUNI VM34-619 carburetor is attached to the engine adapter through the intake manifold coupling using worm gear clamps.

Carburetor adjustments are made in accordance with the instructions in subsection 4.6 “Engine maintenance”.

The A73D fuel pump is designed to supply fuel from the tank to the MIKUNI VM34-619 carburetor. The pump is mounted on the snowmobile frame and is connected to the engine crankcase by a pipe.

Exhaust system. The purpose of the exhaust system is to remove exhaust gases from the engine cylinders into the atmosphere and reduce exhaust noise. The exhaust system includes a muffler and a connecting pipe through which the muffler is connected to the exhaust pipe of the cylinders. The muffler is springs attached to the snowmobile body and engine.Engine mount (fig. 2a). On the frame of the snowmobile, the engine with a sub-motor base is fixed at four points. The resilient engine mount reduces the transmission of vibration from a running engine to the frame of the snowmobile, as well as the transmission of shocks and vibrations to the engine.

when the snowmobile is in motion.

Elastic engine mounts consist of rubber shock absorbers 5, worn on nuts 6 and bushings 13. The nuts 6 themselves are screwed onto mounting bolts 2 and 12 inserted by square head restraints into the frame holes. On the supports, the sub-motor base 7, together with the engine, is installed so that the bushings and nuts 6 enter the holes of the springs of the sub-motor base. The shock absorbers are pulled together by the fastening nuts 1 until the washers 3 and 14 stop at the ends of the nuts 6 and bushings, respectively. Tightening torque for nuts 2.2. 2.5 kgf  m.

The engine is attached to the sub-base with four studs screwed into the tides of the lower half of the crankcase. To ensure the adjustment of the distance between the variator pulleys, which is made by moving the engine, there are grooves in the submotor base for the engine mounting studs. After adjusting the distance between the pulleys, the nuts securing the engine to the sub-engine base are tightened with a torque of 5.0 ... 5.1 kgf  m. During operation, the tightening of the nuts should be periodically checked, since engine displacement leads to a quick failure of the variator belt.

Rice. 2а - Engine mount

1 - nut; 2 - bolt; 3 - washer; 4 - spring; 5 - shock absorber; 6 - nut; 7 - base;

8 - hairpin; 9 - nut; 10 - spring washer; 11 - washer; 12 - bolt;

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Details Created on 11/16/2011 12:13 PM

Such modernization should be treated with deliberation, since exhaust system loses the ability to transfer heat to the external environment and its internal parts begin to experience temperature loads that are not designed for. As a result, segments begin to burn off inside the muffler, which subsequently move freely, creating metallic sounds that are not characteristic of the operation of a snowmobile. Nevertheless, in each case, the duration of the destruction of the muffler is individual and can last for years.

A more correct solution should be considered a separate air supply to the air intake or the use of a heat shield from the effect of a muffler. There is no need to talk about it, all the photos below give a clear idea of ​​how this is possible. There are snowmobiles that normally have air intake through a special channel - a casing from the external environment. It is undeniable that the possibility of direct air intake from the street space improves engine cooling and decreases cylinder temperature.

The next effective step in improved engine cooling and decrease in cylinder temperature in general - the installation of a screen between the exhaust manifold and the engine cylinders. This idea has been used on imported snowmobiles almost from the founding of snowmobiling in Russia.

The task of such a screen is to cut off the air flow passing through the cylinders and prevent it from additionally warming up, in contact with the red-hot exhaust manifold. On the assembled engine, it looks something like this. Moreover, as can be seen from the photo, the cooling jacket is practically absent at the exit point of the exhaust pipe.

Since about 2001, a similar solution began to be used on the engines of the Buran snowmobile, installing on the inside cooling jacket air flow divider

In the absence of such a solution on your snowmobile, we strongly recommend that you take this method into service, make a plate and install, regardless of the brand of the snowmobile. Moreover, recently a similar design has been used at the plant when assembling the engines of the Taiga snowmobile. The design effect is very noticeable even without the use of electronic engine temperature sensors.The thermal stress of the left cylinder is especially strongly reduced, and the temperature difference between the left and right cylinders is also minimized. As an example of self-use of this method, the photo below can serve as the part of the cooling jacket, highlighted in yellow, has been removed.

There are craftsmen who install two fan impellers on a snowmobile. The method is very controversial, since, in theory, the work of two impellers of unidirectional rotation will be accompanied by excessive air turbulence - to interfere with each other. In practice, no one has carried out the study and the air flow increases or weakens, it is impossible to say

The last significant revision of the cooling system is an increase in the speed of the fan impeller. This is achieved by changing the dimensions of the pulleys with the simultaneous use of the non-standard dimension of the fan belt. For such modernization, as a rule, it is necessary to contact a turner and be able to select fan belts.

Where to begin your journey to lower engine operating temperatures is up to you. The main thing we have tried to communicate clearly is that there is a vast field for activity. And only you can decide whether to leave everything as it is or by improving the cooling of your snowmobile to increase its operational properties, which means driving safety

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