Yamaha boat motors DIY repair

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Below are the optimum RPM ranges for the outboard motors at full throttle and maximum boat load. The engine speed when the boat is moving and with a properly selected propeller should be within the upper half of the specified range.

Select screws that meet these requirements.

2-STROKE OUTBOARD MOTORS

9.9F, 15F, E9.9D, E15D, EK9.9D, EK15D, EK9.9J, EK15P

E25B, 25B, E30H, 30H, 25X, EK25B, EK25C

55D, E60J, E65A, 75A, E75B, 75C, 85A, 90A

Z150P, Z175G, Z200N, Z150Q, Z175H, Z200P

0 * Left-hand propeller models have the same optimum RPM as right-hand propeller motors.

4-STROKE OUTBOARD MOTORS

F40D, F50F, FT50G, F60C, FT60D

F75B, F75C, F80B, F80C, F90B, F100D

F / FL200C, F / FL225B, F225C, F / FL250A, F / FL250B

If engine RPM exceeds recommended, replace propeller with a larger pitch propeller.

If engine RPM is lower than recommended, replace the propeller with a smaller pitch propeller.

Do not allow the engine to run at more than the recommended speed for prolonged periods of time, as this may damage the engine.

0 * A 25 mm change in propeller pitch will result in a 200 RPM change in engine speed.

In addition, the change in speed depends on the type of propeller, water (salt / fresh), type of vessel (mass and shape of the hull), etc.

0 * When the engine is lifted using the hydraulic lift system, the maximum engine speed will increase.

This topic is perhaps one of the most relevant today, which is quite understandable. Long gone are the days when mainly domestic "Neptunes" and "Whirlwinds" roamed the water, and the appearance of spare parts laid out on the shore and repairs carried out, as they say, "on the knee" were perceived as the norm of life. Now a similar picture can be observed mainly in the outback. The situation has changed dramatically. The market offers the Russian consumer an almost full range of the latest water-motor equipment from abroad. The availability of engines from the world's leading manufacturers raises a number of questions, and our task is to understand them.

The first question and, perhaps, the main one, which, unfortunately, for most motor owners simply does not arise: how to choose the right propeller? This does not directly apply to engine repair, but it is extremely important to ensure the most favorable operating conditions for the engine as a whole and increase its resource. In other words, a correctly selected screw can reduce the likelihood of a malfunction, and therefore avoid the repair itself. The fact is that any outboard or stationary engine has a certain rpm range, in which it will develop maximum power and at the same time have optimal fuel consumption. Going beyond this range in one direction or another leads to a decrease in engine performance and an increase in fuel consumption.

There are a number of motors, the connection of tachometers to which is not structurally provided. In this case, when carrying out the test, it is necessary to use special tachometers that allow reading information from high-voltage spark plug wires. And to do this, you will have to again contact a service center equipped with a similar tool. And one more note: the standard propellers that come with the motor are usually matched exactly according to the results of such a test, but remember that your equipment (motor, propeller, boat, load) may become an exception to the rule.

Suppose that by selecting the propeller we have created the conditions for the engine for normal operation. But technique is technique, and breakdowns are still possible. True, there is a difference between breakage and breakdown. Therefore, let's try to figure out how to behave in a given situation.We will immediately exclude the option when the life and health of people depend on the performance of the motor - any interventions are permissible here. We will only consider the issues of current repairs.

It turns out that even a normally running motor requires periodic maintenance. Can you do it yourself? There is no definite answer, and here's why. If you are a technically competent person with experience in dealing with such equipment, and the motor is under warranty, it is advisable to obtain permission for scheduled maintenance from your nearest dealer. Most likely, such permission will be given, and then - down with self-confidence. Begin by carefully reading the instruction manual. In the list of routine maintenance, items are possible that are intended only for your specific motor. Lubricants and equipment used for servicing must be original.

After the expiration of the warranty period, the frequency and quality of maintenance remain on your conscience, although you will most likely not be able to completely avoid communicating with the service workers. In the list of routine maintenance specified in the operating instructions, there are those that require high qualifications, special tools and technical documentation. As for the various adjustments, the instruction limits the degree of intervention. You should be especially careful with carburetor settings. Excessively high idle speeds can lead to damage to gearbox parts due to the more severe shock mode when shifting gears. Incorrect adjustment of the mixture quality will lead to a deterioration in the engine operating conditions, which can entail quite serious consequences. I strongly advise against synchronizing the carburetors of four-stroke engines - without a special tool and a certain skill, the result will be negative. And one more tip: do not neglect the preservation of the engine (the procedure is described in detail in the instructions) and proper transportation, especially of four-stroke.

Repair associated with the replacement of any engine components or requiring serious diagnostics directly depends on the degree of technical training of the motor owner and equipment. The range of engines currently used on boats is diverse: they are simple carburetor engines, fuel injection systems for four-stroke and two-stroke engines, with OptiMax systems from Mercury and HPDI systems from Yamaha, and with various lubrication systems. All this requires constant professional retraining even from full-time mechanics. Of course, the owner of the motor is not faced with such a task, but he will not receive complete technical documentation for his motor anywhere. It is outlined in the "Service Manual" - a book used by mechanics. It does not go on sale. And if it will probably be possible to understand low-power carburetor motors, and flaws in the repair will not cause consequences, then a sane person himself will not approach a large motor, as "packed" as possible with electronics. And with all due respect to the craftsmen, I do not advise you to trust the engine to a master from a nearby garage. It is your motor that may be structurally different from those that it has successfully repaired before.

There is one more question, the answer to which must be found before proceeding with the repair: do you have a special tool? Having been engaged in the service of imported motors for far from the first year, I have seen enough and heard enough of everyone, but more often they say one thing: “Yes, I didn't have to do it myself. And how much will it cost now? " There is only one rule: if none of the tools you know are suitable for removing or unscrewing a part, stop - most likely a special tool is required for this procedure.I will say more, the tool that you think is suitable can affect the parts precisely in those places that cannot be loaded. In this case, you will not only break the part, but also significantly complicate the subsequent repair.

What I would like to draw the readers' attention to is the problem of spare parts. Where to get them, use "relatives" or find something suitable, does a worn part require replacement or will it still serve? In my practice, there was one motor on which an anti-corrosion anode, not original, but cheap, lasted longer than the engine, but at the same time had a very good presentation. Do not assume that all non-original spare parts are rubbish. There are also very worthy manufacturers. But, in my opinion, if there is an opportunity, it is better, instead of wasting energy, time, and therefore money on finding suitable ones, to contact technical specialists and be confident in the quality of the spare parts purchased. This, incidentally, also applies to oils. In addition, experts will advise which parts you need to purchase in a particular case, since quite often spare parts need to be changed in a bundle.

Replacing one part will not always correct the problem. A number of gaskets, lock washers, oil seals must be changed during repairs, even if they are outwardly in good condition. As for the clearances, permissible beats, torques and tightening sequence, then in this case it is better to get professional advice, at least by phone, e-mail or regular mail.

It is quite widely believed that it makes sense to purchase the simplest carburetor motors so that you can troubleshoot yourself. This is only partly true. Engines of small and medium power do not require complex technical solutions, but talking about the simplicity of high power motors, even if they are carburetor ones, is incorrect. In order to save gasoline and optimize the quality of the mixture, the fuel systems and ignition systems of such engines are quite complicated, which reduces their advantage over injection or the same OptiMax to a minimum. And given the best power and weight indicators of the latter and their efficiency, the question disappears by itself. Indeed, caution should be exercised when approaching fundamentally new and heavily compressed models. I will say more: complex motors, as a rule, have a protection system that notifies of faults that have occurred and changes the operating mode in such a way as not to damage the engine and at the same time operate it. A complicated-looking engine is often much easier to operate than a carburetor of the same power. Unfortunately, in this matter, many are still very conservative - the engine is frightening, the fear of the electronics with which the injection motors are equipped.

Considering all of the above, I highly recommend making repairs, adjustments and routine maintenance at a certified service center. It is certified. If, for financial reasons or due to the territorial remoteness of such a center, you are forced to carry out repairs yourself, then, again, it is still necessary to consult a specialist.

Within the framework of one or even several articles, it is impossible to outline all the subtleties of repairing an engine. But there are general trends in the maintenance of certain nodes. The table above lists the main points that must be taken into account when starting a repair.

D. Semenov, service manager, Mercury-NII TM, CJSC.

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A properly functioning cooling system is critical to long, trouble-free operation of your outboard. If it seemed to you that there was a problem with the cooling of the engine (for example, there is no control stream of water), you must immediately stop the engine to find out the reason.

Often the problem arises either due to wear or damage to the water pump impeller, or clogged cooling passages.

Cooling impeller sellers claim that the impeller must be replaced every time the gearbox is removed. Never reuse a worn impeller!

Gearbox sellers claim that the gearbox changes every time.

In a free country, everyone decides for himself how often to change cooling impeller and gearbox, guided by the description below and understanding the principle operation of the cooling system on the outboard motor.

If there is no water in the control, do not rush to panic and remove the gearbox to replace the impeller - try to clean the control with a wire. Yet control is primarily for monitoring the operation of the cooling system, and the absence of water in it does not in any way affect the operation of the cooling system.
Due to the smaller hole diameter, the control is often clogged with outboard debris.

The cooling system of an outboard motor is usually a water flow. Consists of an intake, a pump and pipelines (see diagram-drawing).

In single-cylinder motors, cooling water can be supplied from behind the bead by the flow pressure, which is thrown by the propeller and captured by a special water intake nose located on the gearbox housing.

In motors of higher power, cooling water is supplied by a pump, which is mainly used as a rotary pump. It is mounted on the vertical shaft by means of a key.

It is not always possible to immediately detect the lack of cooling in a boat motor.
The first sign of engine overheating will be a gradual decrease in RPM. When the water supply to the system is stopped, the upper cylinder, which has a higher initial temperature, overheats faster and becomes more damaged.

Motors stopped at this stage engine overheating, no seizure in the cylinders or seizure of pistons is detected.

In fact, everything is arranged much more complicated and technologically advanced than on the conventional diagram shown above. In order to be convinced of this, it is enough to look at the cooling scheme of the Mercury F30 / F60 outboard motor.

The rotary pump [1] consists of a body and a rubber impeller.

When the engine is running, water sucked from behind the side by the pump [1] is pumped through the tube [2] to the crankcase cover, passes through the channels into the water jacket of the cylinders, in the muffler cavity and goes out.

To control the operation of the cooling system, a hole [3] is provided, popularly referred to as “control”, through which water should flow out when the engine is running.

(In an imported motor, it hits with a neat trickle almost immediately after the motor starts working).

For automatic adjustment of the cooling water supply, a thermostat [4] is installed on the motor, which maintains the optimal temperature regime of the engine operation, which significantly increases its service life.

Because the thermostat works in dirty seawater, then quite often it starts to jam - it does not fully open or does not close. The opening temperature of the thermostat is about 85 °.
The functionality of the thermostat is easy to check by dipping it into hot water - the valve should open about 10mm.

Incorrect operation of the outboard motor cooling system not necessarily related to overheating, it could also be overcooling if the thermostat stuck open.

A thermostat from a Yamaha F115 outboard motor is shown as an example.

Dedicated to owners of outboard motors and all those who are going to buy a boat motor. Even if you are well versed in the structure of a car engine, it is not a fact that you will be able to cope with a common outboard motor malfunction or be able to successfully diagnose this malfunction. But don't worry, we will help you.

Most owners of inflatable boats with motors take very careful care of the boat, but as far as the motor is concerned, they think that the outboard motor is either working or not.If it does not work, then you need to immediately call a familiar mechanic.

Of course, all modern outboard motors of well-known brands such as Yamaha, Tohatsu, Mercury, Honda are distinguished by a high degree of reliability and do not require constant intervention. But the truth is that the motor will run longer and better if it is serviced periodically. If you carry out routine maintenance work on the engine once a year (you regularly service your car), such as: cleaning, checking, changing the oil, treating parts from corrosion, this will significantly increase its service life and improve its running characteristics.

Let's take a closer look at these very jobs, the description of which was compiled on the basis of the Yamaha outboard motor service program.

We recommend using a pistol-type syringe or small tubes to lubricate the outboard motor. The grease should be used type “A”, which is resistant to seawater.
If you operate the motor mainly in salt water, we recommend that you lubricate it once a month. Apply the lubricant locally according to the instruction manual for your outboard motor.
Pump the new grease until the grease appears first, and then the new one. Then stop pumping. Swivel joints do not need to be rotated.
Pay particular attention to the lubrication of the lower assembly. If the grease does not come out of it, you should put a stop under the blower and apply more forces to pump the grease.
After the outboard motor lubrication procedure, be sure to remove excess lubricant.

If you are the owner of a Yamaha outboard motor, then you are in principle in luck. These motors are supplied with two sets of attachments that facilitate access to the lubrication points. There is a nozzle for lubricating the gearshift mechanism, which is located under the motor head. To gain access to the gearshift assembly, you will most likely need to disconnect the switch rods. It is recommended annually to remove the power steering link bar from its tube and lubricate it.
Remove the screw nut, screw, and end sleeve from the screw shaft. Inspect the shaft carefully. It should be free of scuffs and wear marks. A worn end bushing should be replaced. Inspect the screw shaft seals. Fishing line is often stuffed there. Then lubricate the screw shaft, replace the bushing and install the screw. Tighten the screw nut half a turn more than you can tighten it simply by hand.

To drain the oil from the gearbox, first remove the upper plug, then the lower one. Inspect the condition of the O-rings on the plugs. On the magnet on the bottom plug, metal particles can accumulate. It is normal for a new motor to have small amounts of metal particles. If the motor is not new and you find a large amount of metal particles on the bottom plug. Change oil. Let the motor run for 10 hours and check the oil again. If the situation has not changed and the chips continue to appear, then you should contact the service center of the motor manufacturer. If you find cloudy stains in the drained oil, similar to coffee with milk, you should also drain the oil, fill in new oil, let the engine run and check the oil again. These stains are the result of water leaking through the seals. If a burning smell comes from a running engine, then this is also not good and you should contact the service center.

Fill the gearbox with fresh grease through the bottom hole. Once you see oil leaking out of the top hole, plug the bottom hole with your finger and replace the top plug. And then the bottom one.

If you notice that the motor does not rise or fall poorly, or even spontaneously lowers, then you should check the fluid level in the hydraulic system of the motor lowering / raising drive. To do this, the motor must be lifted up and fixed in this position. Then check the level.It must reach the bottom of the inspection hole. If the level is lower, top up. A liquid like Dextron ATF is suitable.
When servicing four-stroke outboard motors, change the oil filter as well when changing the oil.

Be sure to mark each one before removing the terminals from the spark plugs. Which one goes to which contact. All contacts usually look exactly the same.
When buying a boat motor, a diagnostic table is included with it. It will help you find and diagnose the problem you are experiencing. (Boat engine spark plugs).

If, during the check, significant discrepancies with the passport data are noticed, you should check the compression in the cylinders of your outboard motor. If it differs by more than 10%, the motor needs repair and adjustment.

When replacing spark plugs, buy only the specified plug type. Always carry a spare set of candles with a socket wrench to remove them in stock.

After installing the plug, first tighten it by hand, and then tighten it another 1/4 turn with a wrench. We recommend lubricating the tip of the spark plug to facilitate the subsequent removal of the contact.

When replacing the fuel filter, install it with the arrow pointing to the right (towards the engine). The shape of a fuel filter is similar to a small can and often also acts as a water separator. If the fuel system has a separate water separator, replace that filter as well. And put the current date on the body of this filter. Carefully fill the fuel filter with fuel before installing. (Caring for an engine with a fuel injection system). You should also replace the bulb pump. Gray pear pumps are more UV resistant and will last longer. If your inflatable boat and outboard motor are accordingly stored for a long time without operation, it is recommended to add a stabilizer to the fuel.

To service the water jet pump, we strongly recommend contacting the service center or to professionals who have already repaired boat motors more than once.

If the fasteners on the deyduv are old, then it will be very difficult to remove it. First, remove the bolts from the deyduv, which are located just above the anti-cavitation plate. We recommend that you do this work together.

Sometimes it is necessary to remove the pin under the carburetor that goes through the shift rod. We can assure you that this will not be so easy to do.

New impellers are included in repair kits for water cannons, but before replacing it, carefully study the instructions and diagram in the user manual. Install all parts strictly in the order in which you removed them.

Be sure to clean all seating surfaces and replace all seals.

Before starting the motor with a new impeller for the first time, apply a water-repellent lubricant to the impeller chamber from the inside. This will protect the impeller from being melted by hot gases when starting the motor.

It is imperative that before each use of the outboard motor and boat, make sure that it is securely attached to the transom, check the fastenings of the steering rod control system, throttle control rods and gear shifting.

Inspect the fuel system. Are there any leaks in it. Does the smoke come from where it shouldn't come from?

Treat and repair damage and chips of the motor housing immediately. This will protect the motor from corrosion.

Never paint zinc anodes. Cover the bonnet with wax and polish.

Always store the engine with a full tank of fuel.

vlad B 05 Feb 2004

denco 05 Feb 2004

vlad B 05 Feb 2004

The topic is interesting and relevant, it will be interesting to hear about the nuances of repair, etc. In general, the beginning is intriguing.

In general, this is a topic for a good article, since it turned out that very few people are engaged in this - who have experience - let's share, there is a little experience in repair. Yamaha 25 with a long leg. 20 years old. killed state,
Now I am preparing the renovation for the season. There were questions and a lot - I gradually figured it out. It was hard with the assembly drawings, and catalog
numbers but it's behind.Now parsing the crankshaft to replace the bearing and labyrinth seal. Minor repairs of everything else and making it look decent.

denco 05 Feb 2004

vlad B 06 Feb 2004

A man again speaks in riddles - intrigues.
At least I could say a word about what was wrong, in general about the design, technical solutions, etc.

And the solutions are as follows - if there is no way to purchase a native roller 305NVI
then our 305 roller will go with a little money, i.e. on the outer surface, you need to grind a groove for the retaining ring with an elbor and install the bearing with the collar of the inner ring to the crankshaft cheek (our bearing has a step on the inner ring and does not have a native one).

The pump plate had to be made of stainless steel of the same thickness - since the native had a production. (but you can take a thicker one)
The labyrinth seal is made of duralumin, taking into account wear.

The thermostat was clogged with salt, cleaning and boiling in a decalcifier completely restored its performance. In the same way, you can “brine” the cooling system - it helps.

There was a desire to cut a long leg - but I had to refuse,
can only be trimmed with a super-long leg they have a special insert.

rereg 21 Aug 2006

Perhaps not in the subject, I immediately apologize. Situation. New Yamaha 30 HMHS, there was a strange rustle in the period of 10-50 hours. The company service made the diagnosis: the engine was operating under conditions of oil starvation (the cylinder walls are dry), there were seizures on the walls, and the upper bearing began to self-destruct. Major repairs are required (of course, at my expense).

This is my fifth motor and I know how to handle them. I could not refill the required amount of oil, I don’t buy gasoline anywhere. Tell me, is such a jamb with a motor possible through my fault, or have I stumbled upon a defective motor?

rereg 22 Aug 2006

JinnFX 22 Aug 2006

The fact of the matter is that the lubrication is not separate - I mix oil into gasoline.

Missed: Yamaha-new. Did you comply with the running-in mode?

rereg 26 Aug 2006

Missed: Yamaha-new. Did you comply with the running-in mode?

I say the fifth is the motor. I kept everything with a margin.

I say the fifth is the motor. I kept everything with a margin.

In that case, butter-shit!
Or are you saying that what happened was the fault of the manufacturer?
It was also possible that the engine overheated, and this is the owner's fault.
Well, the new motor doesn’t come out, but it’s one of the best in the WORLD!
hours of work - unless it was made somewhere in the basement from plasticine!
If the engine started and worked, then the oil came there for sure, this is the principle
work in general two-stroke, where oil is added to gasoline.
Unambiguously either overheating or oil quality.
I sympathize with you.

JinnFX 27 Aug 2006

I say the fifth is the motor. I kept everything with a margin.

In this case, I join the Alex-BMW. We must look at the oil. If the bearings are blue, it means that there was a lot of friction, with simple overheating from a clogged pump, I did not see this.

JinnFX 27 Aug 2006

It was hard with the assembly drawings, and catalog
numbers but it's behind.

I have a Yamaha brand disc. There are assemblies and part numbers. True, I never used it, as I bought it - God had mercy

rereg 27 Aug 2006

Unambiguously either overheating or oil quality.
I sympathize with you.

Quicksilver TC-W3 standard. We took it from the dealer, as always. It still remained, we were also advised to hand it over for examination.

You may be right about overheating. Rustle appeared at low revs. Recently, five of us went to one big lake. Boat MLK-8 (elastic band, carrying capacity 800 kg), 130 liters of gasoline, a lot of beer, and everything that may be needed for 4 days of wild rest. We put the 9th screw, because understood that the boat would be heavily loaded. Nevertheless, she did not develop speeds of more than 10 km / h (according to GPS). The difference in speed at maximum and half speed was 2 km / h. We decided that there was no point in firing gasoline and went to half the gas. On the 2nd day it rustled.Accordingly, the question is: could the motor overheat if it worked at 2500-3000 rpm for 1.5-2 hours at a time? The cooling system worked normally, the seawater temperature was less than 10 degrees.

Quicksilver TC-W3 standard. We took it from the dealer, as always.

Nevertheless, she did not develop speeds of more than 10 km / h (according to GPS). The difference in speed at maximum and half speed was 2 km / h. We decided that there was no point in firing gasoline and went to half the gas. On the 2nd day it rustled. Accordingly, the question is: could the motor overheat if it worked at 2500-3000 rpm for 1.5-2 hours at a time? The cooling system worked normally, the seawater temperature was less than 10 degrees.

Let's start in order - what kind of oil does Yamaha recommend for its motors?
And the oil is called YAMALUBE 2! Below I post a photo from the brochure, which was given to me by our official dealer Yamah-boat motors!
The following is an oil specially for outboard motors - look carefully
on the packaging of the oil, there is a corresponding icon!
You bought TCW-3 - this can be a regular two-stroke oil!
There is an inscription on the packaging - what is the oil for outboard motors?
In what proportion did you mix the oil? It is important!
According to your description, it seemed to me that you overloaded the motor - it was necessary
put the propeller lighter and carefully set the motor in height and tilt angle.
Overheating might not have been (especially since your motor has a warning
overheating of the engine] - well, you cannot walk on a non-rolled motor with a load
in five people and even a lot of all kinds of cargo - this is already part of the reason!
Summary - there is a clear violation of the running-in mode both for oil and for operation - you are guilty of what happened! Alas.

rereg 27 Aug 2006

Summary - there is a clear violation of the running-in mode both for oil and for operation - you are guilty of what happened! Alas.

Dear alex-bmw, no offense, I would advise you to read carefully what is written above and not make such impetuous conclusions.

Dear alex-bmw, no offense, I would advise you to read carefully what is written above and not make such impetuous conclusions.

Yes, I read carefully, it would be necessary to put an 8-inch screw, or better-
do not load the motor with such a load during running-in.
Running-in is not only a limitation on the maximum speed, but also a limitation on the load.
But the main reason is the oil. I think so.

JinnFX Aug 31, 2006

Let's start in order - what kind of oil does Yamaha recommend for its motors?
And the oil is called YAMALUBE 2! Below I post a photo from the brochure, which was given to me by our official dealer Yamah-boat motors!

Yamaha, as it was probably noticed, does not produce petroleum products.

The following is an oil specially for outboard motors - look carefully
on the packaging of the oil, there is a corresponding icon!
You bought TCW-3 - this can be a regular two-stroke oil!

No. TC-W3 is anyway outboard motor oil... Not for chainsaws, not for mowers, but for outboard two-stroke motors.
See TC-W3 certification program:
Certification program
So there can be no complaints on this issue.

Summary - there is a clear violation of the running-in mode both for oil and for operation - you are guilty of what happened! Alas.

JinnFX Aug 31, 2006

Recently, five of us went to one big lake. Boat MLK-8 (elastic band, carrying capacity 800 kg), 130 liters of gasoline, a lot of beer, and everything that may be needed for 4 days of wild rest. We put the 9th screw, because understood that the boat would be heavily loaded. Nevertheless, she did not develop speeds of more than 10 km / h (according to GPS). The difference in speed at maximum and half speed was 2 km / h. We decided that there was no point in firing gasoline and went to half the gas. On the 2nd day it rustled. Accordingly, the question is: could the motor overheat if it worked at 2500-3000 rpm for 1.5-2 hours at a time? The cooling system worked normally, the seawater temperature was less than 10 degrees.

So the motor was run in by that time? And in what mode?

rereg 01 Sep 2006

So the motor was run in by that time? And in what mode?

Dear, I wrote that this is my fifth engine. Rustle appeared somewhere after 30 hours. Running-in - 10 hours. The engine's running-in mode was one-to-one, as written in the manual (and even with Yamalube2 only oil!) On a light boat Ob with a crew of 2-3 people maximum, with a continuous operation time of more than 1.5 hours. After running in, I was on the prescribed MOT, which the branded service wrote about in the coupon - no problems.

This manual is intended for use by Yamaha service personnel who repair and service Yamaha equipment. To use this manual, you must have a basic knowledge of mechanics and electrical engineering, as well as skills in these areas. Attempts to carry out repairs or maintenance without this knowledge may result in an accident or damage to the equipment.
Since Yamaha is constantly working to improve its products, therefore, your motor parts may not fully match the descriptions or illustrations in this book. Use only the most recent version of the manual. Yamaha authorized dealers are periodically notified of design, specification or repair changes, all of which will be included in the next revision of this manual.

Content
1. General information
2. Specifications
3. Periodic checks and adjustments
4. Power system
5. Engine
6. Deadwood, reducer
7. Bracket
8. Electrical system
9. Troubleshooting

Manual format
All procedures in this guide are presented in a step-by-step format. The information is presented in such a way that it is easy to read, all the necessary explanations are provided for all disassembly, repair, assembly and inspection operations.
For example, first the component is indicated, then its possible state (malfunction) and after the arrow, the actions to be taken. To help you find the information you need in the manual, section icons and important headings have been moved to the top of the page (header).

Engine model indication
Model 25VMN 30NMN
Designation 25VMN 30NMN

Illustrations
The illustrations in this manual are for all of the above models.

Cross-references
Cross-references have been kept to a minimum and will point you to the correct paragraph or section.