Boosting the Ural motorcycle engine: what is it and why is it needed?

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.

INCREASING URAL ENGINE POWER

Many motorcyclists dream of increasing the engine power of their Urals. But not everyone understands what should be done for this and what consequences boosting the power unit can lead to. Firstly, work related to changing its design can only be carried out by a very qualified mechanic and with the availability of machine tools. Attempts to do something in a hurry are doomed to failure. Secondly, the engine, boosted according to sports-cross models, has a torque characteristic of little use for economic purposes, shifted to the high-speed zone and unimportant fuel efficiency. So before you start changing anything in the factory design, think carefully about whether you can handle a very serious job and whether you need it.

This material is a generalization of the experience of reconstructing the engines of serial road motorcycles M-63, M-66, M67-36, as well as serial sports engines M-63K (motocross) in preparation for competitions and runs by athletes of the DOSAAF society.

ATTENTION! Boosting an engine may be advisable only if it is practically new or has undergone a thorough overhaul. If your power unit does not meet the specified requirements, then there is a risk of losing what you have.

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.

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.

Do-it-yourself Ural motorcycle tuning

If you own a Ural motorcycle, but its appearance does not suit you, and you constantly look at foreign handsome men, do not despair. You can improve your vehicle. Most often, they buy a domestic motorcycle just for the shell, and everything else is redone.

Tuning the Ural will take you a lot of time, but it is a very exciting process, and the result will exceed all your expectations.

Before you get started, check out all the proposed upgrades and photos of motorcycles on the Internet.

Having decided, you can begin work. First we redo the rear part of the frame.

• The pendulum needs to be expanded.
• Cut off the seat tubes.
• We weld curved pipes with a diameter of 28 mm, no less. This is not only a beautiful decor, it is also a headscarf amplifier.
• To make the suspension softer, the rear shock absorbers need to be installed at an angle.
• When you put the wide rear wheel in place, make sure that the rubber coupling works without distortion.
• The footrests need to be moved forward, it will be more comfortable for your legs.
• The frame needs to be lengthened by ten centimeters.
• The engine moves backwards.

Perhaps in this case the landing will be incorrect. But for every motorist it is different, individual.

After completing all the work, select a workpiece, perhaps from a stroller, for the rear wing. If you want it to be deeper, you can cut plates from it and butt weld it to the wing.

Let's start working on the tank:

• Use a grinder to remove the glove compartment.
• You also remove the neck and tunnel.
• A wedge is used to cut the top of the tank.
• The two halves are welded at the back. And the neck and tunnel are welded.
• To keep everything sealed, use epoxy resin.

Now we work with the seat:

• You need to cut the base from two-millimeter steel.
• Place thin foam rubber under it.
• The finished structure can be covered with either suede or leather.

The steering wheel needs to be made simple. Everything is cut from a single piece of metal. This is the handle, clutch lever, brakes. For the mirror stand, cut blanks from eight-mm steel. You can buy a housing for a mirror in a store or make it yourself in the form of a sphere.

Silencers are located on the right side.

• Weld the left exhaust pipe without bending it.
• The right pipe remains standard, but it needs to be shortened a little at the top so that the leg does not melt.
• The seams are cleaned, polished and chrome plated.
• To get a chopper sound, you can insert valve springs from a car into the mufflers.

Engines in the Urals can be boosted. When working properly, its power increases to forty-two horsepower.

Ural tuning video

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.

Engine MT-8 (650 cm 3)

1. Check that the ignition is installed correctly on each cylinder. The ignition timing should be 40°-42°. Synchronous operation of the ignition system is achieved by filing the cam in the distributor and bringing it to the same ignition timing on both cylinders.

2. The valve timing is checked using a graduated disk mounted on the axis of the crankshaft. The valve timing must correspond to:

Inlet start to c. m.t. 70°;

end after n. m.t. 140°.

Release beginning BC m.t. 110°;

end after c. m.t. 90°.

Adjustment of the valve timing can be done on the removed cam shaft by filing it by hand using a drill and cam stones.

3. Cleaning the channels in the cylinder heads from casting errors gives 2 liters. With. And adjusting the compression ratio in each cylinder will also add power due to the uniform operation of the two cylinders.

4. Installing K-301B carburetors with an increased diffuser diameter to 26 mm will also add 2 liters. With.

5. Selection and adjustment of inlet pipes behind the carburetor to the entrance to the air filter / = 345 mm, d = 37 mm.

6. Adjustment of carburetors for synchronized operation, equal jet flow rate of 250 cm/min.

7. Installation of an air filter from Moskvich-412 (2 pcs.) or Volga GAZ-24 cars.

8. Selection of the length and diameter of exhaust pipes and mufflers (Fig. 1).

The recommendations listed above, implemented on the motorcycle, allow you to increase engine power to 42 hp. s., and if you change the compression ratio, bringing it to 8.5, then the engine power will increase to 45 hp. With. at 5900 rpm (according to VNIIMotoprom). Increasing the cylinder diameter to 80-82 mm by increasing the volume of the cylinders gives good results. Piston rings can be used from a motorcycle ESO-350 or CZ-360, Moskvich-412. This event allows you to further increase engine power, bringing it to 48-50 hp. With.

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.

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.

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