Ural motorcycle engine tuning: detailed information

Many motorcycle owners take up the task of remaking their iron horses, trying to give them individuality. At the same time, the final result obtained due to the changes made is not always satisfactory. A striking example of this is the legendary Ural motorcycle, tuning of which is associated with certain difficulties. Due to the significant prices for components, such an operation will cost more than, for example, tuning an IZH 5 Jupiter.

A little history

The products of the Irbit Motorcycle Plant are well known not only in our country. Various models, whose design originates from the pre-war BMW R71, have retained their parental genes for seventy years. True, the prefix “Ural” appeared in their name a little later. Since 1961, it has been assigned to the following modifications:

• M-62(1961 – 1963).
• M-63 (1963 - 1971) - this was the so-called Ural-2.
• M-66 (1973 – 1975) received the Ural-3 marking.

Next, it was decided to limit ourselves to the name Ural, removing the additional digital index and leaving only the factory designation.

• M-67 (1973 – 1976).
• M-67-36 (1976 – 1983).
• IMZ-8 (this model has been produced since 1985 and has many different versions).

And this is not counting special versions and limited editions. But in the process of tuning a motorcycle, any of the listed modifications have a lot in common. Despite the changes in the name, all models are similar in design and have similar technical characteristics.

Exterior

According to the performance characteristics of the Ural-4320, it is equipped with a metal platform body and a tailgate. The car is equipped with benches, an awning and removable arches. There are also additional lattice sides. The standard equipment includes a three-seat cabin, assembled from thick-walled sheet metal, manufactured by stamping. Thoughtful glazing and rear-view mirrors make it possible to fully monitor the situation on the road and increase visibility.

Structurally, the body is made in the form of short overhangs, which improves cross-country ability. The curb weight of the truck is 8.2 tons. The weight of the transported cargo is up to 67.8 tons with the ability to tow 11 tons.

Tuning or restoration?

Remaking new equipment is not very justified financially. It is cheaper to purchase a used, or even broken, copy, and first restore it. If you get your hands on a rare Ural motorcycle, restoration and repair of the rarity will bring greater dividends than the most advanced tuning. After all, in this way we restore and bring history itself back to life.

If the model is ordinary, then there will be nothing wrong with turning an ordinary Ural into a tuned one. In any case, the first step will be to restore the Ural motorcycle to working condition.

Weaknesses of the IMZ-8.103-10 (IMZ-8.103-30, M-67-36) engine of the Ural motorcycle

• Foot starter (kickstarter);
• Gas and clutch cables;
• Generator;
• Carburetors;
• Cylinder heads;
• Reverse gear (gearbox).

More details about the weak points of the motor...

The foot starter of the IMZ-8.103-10 engine is a weak point due to the slippage of the pawl. The malfunction is eliminated after dismantling the gearbox and disassembling it with rearranging the pawl with the other side or replacing it. I have an assumption that the metal of the dog is of low hardness. On the other hand, if the pawl is made harder, the gear will fail. You need to choose the golden mean.

The clutch control and fuel supply cables are a weak point due to their short service life. To put it simply, they tear, and before that they stretch, which makes it necessary to adjust the timing of the supply of the fuel mixture, as well as the clutch.

The generator does not run for a long time.

Gasoline gets into the floats, after which the cylinder is filled with gasoline. In addition, carburetors are not matched to these engines; half of the fuel goes to waste, which is not economical. It would be nice if the engine had one carburetor instead of two.

Do not overtighten the spark plug heads; the threads break off quite easily. You cannot overheat the engine, the result will be clearly visible on the heads, the studs are pulled out, leading to the landing plane of the heads. If you are unable to avoid breaking the spark plug thread, contact a familiar turner; he will be happy to repair it and install a steel threaded bushing for a modest fee. I can recommend the same for wear of valve seats and chamfers. It is much cheaper to repair heads than to buy new ones; a good turner can do this in no time.

The reverse gear does not work for a long time due to the rapid wear of the reverse gear in the gearbox.

Choosing a case that suits your needs

Having set the goal of tuning a Ural motorcycle with your own hands, it is important to understand that there are modifications that are relatively painless and do not require documentary evidence to register the vehicle and undergo a technical inspection.

And there are changes that, in order not to conflict with the law, must be agreed upon with the manufacturer or other regulatory authorities. Based on this, tuning for a Ural motorcycle should be divided into two categories:

• Painless, after which there will be no additional paper problems.
• Complex, ideally requiring official paper approval.

We will consider each of these categories separately.

Ural's position now

Before the notorious events of the early nineties, about three million devices were produced. After the collapse of the Union, the plant's position began to deteriorate. The purchasing power of the population fell sharply, factories in the country were closed and sold off. Fortunately, the unenviable fate passed the Ural. Production continued. These were mainly motorcycles with a sidecar (with or without a drive), with a 4-stroke opposed two-cylinder engine with a volume of 745 “cubes” and a power of 40 “horses”, plus 4 gears and reverse gear.

Since the mid-90s, almost all parts in the design of the Ural motorcycle have been improved or replaced with new ones. In honor of the 70th anniversary of the plant in Irbit, modernized models were produced, one of the best is the Ural motorcycle with M70 Sidecar tuning.

The sale of models already produced in Russia, and not in the USSR, is aimed at foreign countries. 97% of all models of the plant are sold in the USA, Europe, Canada, and Australia. Asia is considered as one of the promising markets: Japan and Korea. In these countries there are simply no competitors in the niche of motorcycles with sidecars, but there is demand. China, as a sales market, has been producing a replica of the M-72 under the guise of a copy of BMW since the 50s.

Painless changes

You should not assume that any painless tuning for a Ural motorcycle will be easy to do. But, as they say, hunting is worse than bondage. For clarity, we will divide possible alterations into external and internal. The external ones are aimed at correcting the veteran’s appearance, while the internal ones will affect his driving performance and technical characteristics.

Appearance correction

Classic shapes, characteristic of all models without changing, go well with an abundance of chrome parts. Since chromium has good anti-corrosion resistance, it is not forbidden to use it even in the most unexpected places. After this processing, many details will look good:

• Front and rear wings.
• Fuel tank.
• Side panels.
• Engine crankcase, cylinders and cylinder heads.
• Frame and suspension elements.

But if there is no opportunity or desire to do chrome plating, high-quality painting of a Ural motorcycle can be an alternative. There will be room to turn around, especially if you have a modification with a stroller.

Good results can be achieved by installing wings of a different style and size, a different fuel tank, roll bars and even optics. Many favorite modifications - installing a high steering wheel and new control handles, altering the seat - without the right approach, they worsen the rider's position, making it less comfortable. Such changes should be made with caution.

Inner harmony

Many owners start tuning the Urals to improve the technical characteristics of the motorcycle. Despite some orthodoxy in the design of the engine and gearbox, there is room for improvement here. The following steps can be taken:

• Installation of crankshaft (crank) support bearings, the quality of which is better than standard ones. It is not recommended to reduce the size of the support necks themselves. After all, this removes the heat-treated layer and reduces the strength of the critical elements.
• Reduced weight of pistons and connecting rods. Excess mass of these parts leads to an increase in the moment of inertia and a decrease in engine power. Even simply by removing the casting flash, you can significantly reduce the weight and increase the effective output of the power unit.
• Alignment and grinding of inlet and outlet channels. Grinding in valves. Such procedures will improve the filling of the cylinders with the combustible mixture.
• Manufacturing a new camshaft with a different cam profile, allowing the valve timing to be changed. This is a complex engine tuning that requires special knowledge.
• Installation of new carburetors. A well-proven measure that allows you to get rid of failure during acceleration, which is characteristic of all IMZ models without exception.
  This is due to the fact that the manufacturer equips the equipment with variable-discharge carburetors, which are poorly suited for four-stroke motorcycle engines. You can get rid of this by equipping the motorcycle with suitable constant-vacuum carburetors. Both Mikuni and Keihin have such models. To optimize operation, the flow area of ​​the nozzles will need to be adjusted. Ideally, such modifications are carried out on a special stand. In the absence of one, one has to be content with fitting in road conditions. After such engine modernization, the Ural will accelerate much more confidently.
• Replacing standard air filters with others that have similar throughput but less resistance.
• Installation of inertial boost. This will only work if you purchase components from a reputable manufacturer. There are often low-quality or even non-functional components on the market.
• Manufacturing of new gearbox gears. Despite the relative labor intensity, this motorcycle tuning is more than justified. Original gears are often not of high quality and not only make it difficult to change gears, but also make noise during operation.
• Installation of alloy wheels. Such modernization is not always justified. A cast wheel, if it is not spoked, will look ridiculous on a classic.

Whether you make all the upgrades, or just some, in any case, tuning the Ural motorcycle engine will be completely justified.

Cylinders and pistons

One of the most important parts in an engine is the pistons. They take on a huge load from expanding gases and temperature. Low-quality standard pistons do not withstand loads well, often have different weights, and the piston rings cannot provide high compression due to their outdated design, this significantly affects the power, and the massiveness and number of rings make the piston very heavy, which prevents the engine from spinning. It is recommended to install forged pistons with imported rings. A good solution would be to install forged pistons from the Ural Wolf motorcycle; they have a convex surface, which will increase the compression ratio and significantly increase engine power.

As for the cylinders, it is preferable to replace them with aluminum ones with a cast iron liner. The thermal conductivity of aluminum is much higher, and effective heat dissipation is ensured. A significant improvement in cylinders is relining. The standard internal diameter of the cylinder liner is 78 mm, and if the volume of the standard engine of 650 cubic meters does not suit you, by replacing the original cylinder liners with liners from Moskvich 412 with an internal diameter of 82 mm, you can significantly increase the volume and, accordingly, power. Select the pistons accordingly for the new diameter.

To combat overheating, a cooling system in the form of installing an oil cooler and by forcefully spraying oil onto the bottoms of the pistons will be useful. To connect the oil cooler, an additional oil pump is needed, since the standard one is very weak. To pump oil through the radiator, it is advisable to install an oil pump from a Dnepr motorcycle. Drive the second pump through an adapter from the standard Ural pump. In order for the additional pump to fit in the crankcase, an enlarged sump is required, which will also have a positive effect on cooling. By slightly increasing the amount of oil in the system, it will be possible to distribute the thermal load, and the new aluminum pan will remove heat even better.

By connecting to the new oil pump an oil line made of a copper or steel capillary tube, which must first pass into the radiator, then cooled oil from it must flow to the inside of the pistons. To do this, the line from the radiator enters back into the crankcase and bifurcates so that the oil supply is directed to the bottom of the piston from the inside. An oil cooler can be purchased at a Japanese motorcycle dismantling shop, and an automatic transmission radiator of the size you need from any car is also perfect.

Complex modifications

It is not difficult to guess that this category does not include external changes. But the internal ones are quite enough. Carrying out tuning with their own hands, some owners make adjustments to the design of the motorcycle that are prohibited by law.

• Installation of new mufflers. Despite its apparent simplicity, such modernization requires documentary approval. Otherwise, you will not be able to officially pass the technical inspection.
• Frame modification. Having an impact on the strength of the structure, such tuning for the Ural motorcycle requires preliminary calculations, the results of which are confirmed by specialists.
• Making changes to the brake system. In this case, problems during technical inspection will not be limited to. For unauthorized alteration of brakes, the law does not even provide for a fine, but a real sentence. If you are tuning a Ural motorcycle with your own hands and decide to replace the brake drums with more efficient discs, you must coordinate such changes with IMZ representatives, having received documented permission from them.

Ignition

Following an increase in power and replacement of pistons, it is advisable to replace the spark plugs. Spark plugs A20 DV and A17 DV from Zhiguli are suitable for Ural. Some craftsmen install an additional candle. This increases engine power at high speeds, reduces consumption and can become a replacement for boost. But work will have to be done to develop an independent spark generation system. At the same time, the air filter is changed, which reduces friction losses during intake.

If the engine is old, then it is advisable to replace the carburetor and install an injector. This can be done with your own hands or with some help. Tuning the Ural motorcycle can be done using injection spare parts from the VAZ "Ten"

At the same time a new starter is installed. Starters from the Vikhr outboard motors ST 353, ST 367, ST 369 are suitable for IM3. VAZ motors - from models 9, 10 and 11 - are also successfully built in place of the originals.

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The main thing is experience

If you are taking on a motorcycle modification for the first time, you should first experiment with some simpler model. For example, perform tuning of Voskhod 3M - an interesting and very popular model at one time, produced in Kovrov. Thus, you will approach work on the Urals already having some experience. This will help you avoid annoying mistakes.

Previous entry Adjusting the ignition on a Ural motorcycle

Next entry Installing one carburetor on a Ural motorcycle

Specifications

Let's do a full analysis of technical data based on one of the first models - Ural M-62.

Ural M-62

The heavy Soviet motorcycle was equipped with a four-stroke carburetor two-cylinder engine with opposed cylinders and air cooling:

• working volume – 649 cubic meters. cm;
• cylinder diameter – 78 mm;
• piston stroke – 78 mm;
• compression ratio – 6.2;
• maximum power – 28 hp. s., 20.6 kW;
• crankshaft rotation speed at maximum power – 5,000-5,200 rpm;
• maximum torque – 47 Nm;
• carburetor - K-38;
• air cleaner – combined inertial contact-oil filter with two-stage cleaning.

Transmission:

• clutch: dry double-disc, driven discs with linings on both sides;
• cardan transmission: cardan shaft with an elastic coupling and a hinge on needle bearings;
• main gear: a pair of bevel wheels with spiral teeth, gear ratio - 4.62;
• gearbox: four-speed, with gear ratios in 1st, 2nd, 3rd, 4th gears 3.6, 2.28, 1.7, 1.3, respectively.

Electrical equipment:

• ignition system - battery;
• voltage – 6 V;
• battery – ZMT-12;
• generator – G-414;
• relay-regulator – PP-31;
• breaker-distributor – PM05;
• ignition coil - B201.

Chassis:

• frame – tubular double closed type;
• Front wheel suspension – telescopic fork with double-acting hydraulic shock absorbers;
• rear wheel suspension – spring;
• front wheel travel – 80 mm;
• rear wheel travel – 60 mm;
• tire size - 3.75-19 inches;
• brakes are shoe brakes, with friction linings on the front and rear wheels.

Refueling volumes:

• fuel tank – 22 l;
• engine crankcase – 2 l;
• gearbox housing – 0.8 l;
• final drive housing – 0.15 l;
• air purifier – 0.2 l.

Dimensions:

• length – 2,420 mm;
• width – 1,650 mm;
• height – 1,100 mm;
• motorcycle base – 1,100 mm;
• ground clearance at full load and normal tire pressure – 125 mm;
• track – 1,130 mm;
• maximum speed – 95 km/h;
• weight – 340 kg;
• maximum load – 255 kg;
• average operating fuel consumption per 100 km when driving in various road conditions with variable load is 6 liters.

Description

The Ural motorcycle engine is a two-cylinder, four-stroke, air-cooled power unit. It is equipped with an electronic fuel injection system (injector) developed by the engineering company ElectroJet Inc.

The main power element of the motor housing is the crankcase. Structurally, it consists of:

• the crankcase itself;
• distribution box covers;
• front and rear bearing housings;
• pallet;
• front cover.

The crankcase is cast from high-strength aluminum alloy. Pistons and the junction box cover are also made from it. The cylinders that are installed in the crankcase are cast from special cast iron, which has increased strength. Their internal surfaces are honed before installation, bringing the surface cleanliness to almost a “mirror state”. The materials from which the pistons and cylinders are made during operation form a good anti-friction pair that is not subject to severe wear.

In addition to the parts of the cylinder-piston group, a crank mechanism, a gas distribution mechanism, etc. are installed inside the crankcase and on its outer walls. In this case:

• the camshaft is installed in the upper part of the crankcase on bearing supports, and the pushers are located on its two sides;
• the junction box cover is attached to the front wall;
• the oil filler neck with a plug equipped with a dipstick is located on the left wall;
• the crankshaft is mounted on main bearings installed in the walls;
• From below, the crankcase is closed with a special steel pan, which is used as a reservoir with engine oil.

The assembled engine is installed on the motorcycle frame and secured to it with two studs.

Cooling

As engine power increases, the pistons will require additional heat removal. The problem is solved by installing “extra” air intakes. They are made from any sufficiently strong material, even from paint cans. It is important here to secure the intakes well, but not strictly along the axis of the cylinders, but to position them so as not to limit the possibility of replacing spark plugs on occasion.

Bright, stylish, but still Dnepr

Looking at this motorcycle, different emotions immediately appear in me. On the one hand, the author of the project had a hand and spent a lot of time creating this “horse”, but on the other hand, I don’t see much point in them. It is unlikely that this homemade seat will be more comfortable than the standard one.

Exhaust

- the highlight of the whole design. As for me, the “cans” are too massive for the pipes that go directly to the cylinders. I think if they were made thicker in cross-section, this modification would look somewhat more impressive.

The colors here are extremely bright and dull

, but this is
a matter of taste
.
And, according to the classics of the genre, we are witnessing the abandonment of the steering wheel and the fact that the author of the project gave preference to clip-ons, completely cutting down the ability to move around on this motorcycle.