How to Find Yamaha Outboard Parts by Year No two Yamaha outboard models are ever quite the same as each year Yamaha subtly changes and improves its motors. Some outboards may share a few common parts but many of the parts and components in an outboard will be unique to that year's model. Because of this it is essential you know your outboard's year of manufacture and model name before you start buying replacement parts for it, otherwise there's no guarantee the new parts will fit. Your Yamaha outboard's model name and year of manufacture are stamped on an identification plate that is attached to the transom clamp bracket. At the top of the plate is the outboard's model name comprised of letters and numbers. These digits indicate the outboard's basic engine type, horsepower and variant. OEM Yamaha Outboard Parts If there's a Yamaha outboard riffed on the back of your boat then you're the proud owner of the #1 most popular brand of marine engine.

1. Old Yamaha 25 Hp Outboard Motor Manual
2. New 25 Hp Yamaha Outboard

But here you are at Boats.net, the #1 most trusted online source for OEM Yamaha outboard parts and accessories. This can only mean one thing: something is amiss with your outboard and you need replacement Yamaha parts to repair it and restore it to its full potential. Don't worry; we've got you covered thanks to our unsurpassed range of genuine Yamaha marine parts. You are just a click or two away from thousands of Yamaha parts for all Yamaha outboard motors manufactured each year from 1984 up until the present day. On all Yamaha outboards manufactured before April 2005 the last letter of the model name designates the year of manufacture. You can use the Outboard Code Reference Charts on our website to determine your outboard's year from the model name. On outboards produced after April 2005 Yamaha stopped designating outboards by their year of manufacture and instead designate them by generation, starting with the letter A.

New models/generations are indicated with the following letter of the alphabet between the digits indicating the horsepower and the control/tilt method. Using your outboard's year and model name you can select them on our website to access the Yamaha marine parts page for your exact outboard model.

Old Yamaha 25 Hp Outboard Motor Manual

Basic parts of an outboard motor An outboard motor is a system for, consisting of a self-contained unit that includes engine, and or, designed to be affixed to the outside of the. They are the most common motorized method of propelling small watercraft. As well as providing propulsion, outboards provide steering control, as they are designed to pivot over their mountings and thus control the direction of thrust. The also acts as a when the engine is not running.

Unlike, outboard motors can be easily removed for storage or repairs. 1979 70 hp outboard, cowling and air silencer removed, exposing its shift// linkages, flywheel, and three In order to eliminate the chances of hitting bottom with an outboard motor, the motor can be tilted up to an elevated position either electronically or manually. This helps when traveling through shallow waters where there may be debris that could potentially damage the motor as well as the. If the electric motor required to move the pistons which raise or lower the engine is malfunctioning, every outboard motor is equipped with a manual piston release which will allow the operator to drop the motor down to its lowest setting. A motorboat with an outboard motor attached to it Large Outboards Large outboards affixed to the transom using clamps and are either tiller steer up to approx 100hp.

Generally 100hp plus is linked to controls at the helm. These range from 2-, 3- and 4-cylinder models generating 15 to 135 horsepower suitable for hulls up to 17 feet (5.2 m) in length, to powerful V6 and V8 cylinder blocks rated up to 557 hp (415 kW)., with sufficient power to be used on boats of 37 feet (11 m) or longer. Portable Small outboard motors, up to 15 horsepower or so are easily portable. They are affixed to the boat via clamps, and thus easily moved from boat to boat.

These motors typically use a manual, with and gearshift controls mounted on the body of the motor, and a for steering. The smallest of these weigh as little as 12 kilograms (26 lb), have integral fuel tanks, and provide sufficient power to move a small dinghy at around 8 knots (15 km/h; 9.2 mph) This type of motor is typically used:. to power small craft such as, etc.

to provide auxiliary power for,. for aboard larger craft, as small outboards are typically more efficient at trolling speeds. In this application, the motor is frequently installed on the transom alongside and connected to the primary outboard to enable helm steering. In addition many small motor manufacturers have begun offering variants with power trim/tilt and electric starting functions so that they may be completely controlled remotely. Electric-powered Commonly referred to as ' or ', electric outboards are used.

on very small craft or on small lakes where gasoline motors are prohibited,. as a secondary means of propulsion on larger craft, and. as repositioning thrusters while fishing for and other freshwater species, and any other application where their quietness, and ease of operation and outweigh the speed and range deficiencies. Pump-jet propulsion is available as an option on most outboard motors. Although less efficient than an open propeller, they are particularly useful in applications where the ability to operate in very shallow water is important. They also eliminate the laceration dangers of an open propeller.

Propane Propane outboard motors are available from several manufacturers. These products have several advantages such as lower emissions, does not have ethanol related problems, and no need for choke once the system is pressurized.

History and developments The first known outboard motor was a small 5 kilogram (11 lb) electric unit designed around 1870 by, and patented in May 1880 (Patent N° 136,560). Later about 25 petrol powered outboards may have been produced in 1896 by American Motors Co —but neither of these two pioneering efforts appear to have had much impact. The Waterman outboard engine appears to be the first gasoline-powered outboard offered for sale in significant numbers. Developed by Cameron Waterman, a young Yale Engineering student, it was developed from 1903, with a patent application filed in 1905 Starting in 1906, the company went on to make thousands of his 'Porto-Motor' units, claiming 25,000 sales by 1914. The inboard boat motor firm of Caille Motor Company of Detroit were instrumental in making the cylinder and engines. The most successful early outboard motor, was created by inventor in 1909. Between 1909 and 1912, Evinrude made thousands of his outboards and the three horse units were sold around the world.

His Evinrude Outboard Co. Was spun off to other owners, and he went on to success after starting the company to produce a two-cylinder motor - ELTO stood for Evinrude Light Twin Outboard. The 1920s were the first high-water mark for the outboard with Evinrude, Johnson, ELTO, Atwater Lockwood and dozens of other makers in the field. Historically, a majority of outboards have been powerheads fitted with a carburetor due to the design's inherent simplicity, reliability, low cost and light weight. Drawbacks include increased pollution, due to the high volume of unburned gasoline and oil in their exhaust, and louder noise. Four stroke outboards Although four stroke outboards have been sold since the late 1920s, particularly Roness and Sharland, in 1962 Homelite introduced a commercially viable four cycle outboard a 55-horsepower motor, based on the 4 cylinder automobile engine. This was called the Bearcat that was later purchased by Fischer-Pierce who are the makers of Boston Whaler for use in their boats because of their advantages over two strokes.

In 1964, Honda Motor Co. Introduced its first four-stroke powerhead. In 1984, Yamaha introduced their first four-stroke powerhead. These motors were only available in the smaller horsepower range. In 1990 Honda released 35 hp and 45 hp four-stroke models. They continued to lead in the development of four-stroke engines throughout the 1990s as US and European exhaust emissions regulations such as CARB led to the proliferation of four-stroke outboards. At first, North American manufacturers such as Mercury and OMC used engine technology from Japanese manufacturers such as Yamaha and Suzuki until they were able to develop their own four-stroke engine.

The inherent advantages of four-stroke motors included: lower pollution (especially oil in the water), noise reduction, increase fuel economy, and increased low rpm torque., Mercury Racing, Nissan Marine, Suzuki Marine, Tohatsu Outboards, Yamaha Marine, and China Oshen-Hyfong marine have all developed new four-stroke engines. Some are carburetted, usually the smaller engines. The balance are electronically fuel-injected. Depending on the manufacturer, newer engines benefit from advanced technology such as multiple valves per cylinder, variable camshaft timing (Honda's VTEC), boosted low end torque (Honda's BLAST), 3-way cooling systems, and closed loop fuel injection. Mercury Verado four-strokes are unique in that they are. Mercury Marine, Mercury Racing, Tohatsu, Yamaha Marine, Nissan and Evinrude each developed computer-controlled direct-injected two-stroke engines.

Each brand boasts a different method of DI. Fuel economy on both direct injected and four-stroke outboards measures from a 10 percent to 80 percent improvement, compared with conventional two-strokes. Depending on and load at cruising speeds, figure on about a 30 percent mileage improvement. Propane Outboards In 2012, Lehr inc.

Produced the first line of propane powered outboards. Designer marked these outboards as low cost, green, and low maintenance. The first models included a 5 hp option and a 2.5 hp option. Since their introduction, has released their own 5hp versions. The Lehr original currently offers sizes ranging from the original 2.5 hp to 40 hp. Propane's advantages over gasoline include increased fuel stability, lower emissions, and reliability. Outboard motor selection It is important to select a motor that is a good match for the hull in terms of power and shaft length.

Power requirements Overpowering is a dangerous condition that can lead to the transom accelerating past the rest of the vessel and underpowering often results in a boat that is incapable of performing in the role for which it was designed. Boats built in the U.S. Have a Coast Guard Rating Plate which specifies the maximum recommended horsepower for the hull. A motor with less than 75% of the maximum will most likely result in unsatisfactory performance. Shaft length Outboard motor shaft lengths are standardized to fit 15-inch, 20-inch and 25-inch. If the shaft is too long it will extend farther into the water than necessary creating, which will impair performance and fuel economy.

If the shaft is too short, the motor will be prone to ventilation. Even worse, if the water intake ports on the lower unit are not sufficiently submerged, engine overheating is likely, which can result in severe damage.

General dimensions Different outboard engine brands require different transom dimensions and sizes, that affects performance and trim. Outboard Brand - Model Transom Angle Max Transom Thickness Transom To Bulkhead Yamaha - F350 12° 712 mm Yamaha – F300 12° 712 mm EVINRUDE – DE 300 14° 68.58 mm EVINRUDE - G2 300 HP 14° SUZUKI – DF 300 AP 14° 81 mm MERCURY – 300 HP 14° LEHR - 5.0HP 14° LEHR - 2.5HP 14° Operational issues Motor mounting height Motor height on the is an important factor in achieving optimal performance.

The motor should be as high as possible without ventilating or loss of water pressure. This minimizes the effect of while underway, allowing for greater speed. Generally, the antiventilation plate should be about the same height as, or up to two inches higher than, the, with the motor in neutral trim. Trim Trim is the angle of the motor in relation to the hull, as illustrated below.

The ideal trim angle is the one in which the boat rides level, with most of the hull on the surface instead of plowing through the water. If the motor is trimmed out too far, the will ride too high in the water. With too little trim, the bow rides too low. The optimal trim setting will vary depending on many factors including speed, hull design, weight and balance, and conditions on the water (wind and waves).

New 25 Hp Yamaha Outboard

Many large outboards are equipped with power trim, an electric motor on the mounting bracket, with a switch at the helm that enables the operator to adjust the trim angle on the fly. In this case, the motor should be trimmed fully in to start, and trimmed out (with an eye on the ) as the boat gains momentum, until it reaches the point just before ventilation begins or further trim adjustment results in an increase with no increase in speed. Motors not equipped with power trim are manually adjustable using a pin called a topper tilt lock. Ventilation Ventilation is a phenomenon that occurs when surface air or exhaust gas (in the case of motors equipped with through-hub exhaust) is drawn into the spinning propeller blades. With the propeller pushing mostly air instead of water, the load on the engine is greatly reduced, causing the engine to race and the propeller to spin fast enough to result in, at which point little thrust is generated at all.

The condition continues until the prop slows enough for the air bubbles to rise to the surface. The primary causes of ventilation are: motor mounted too high, motor trimmed out excessively, damage to the antiventilation plate, damage to propeller, foreign object lodged in the diffuser ring. Safety If the helmsman goes overboard, the boat may continue under power but uncontrolled, risking serious or fatal injuries to the helmsman and others in the water. A safety measure is a ' attached to the boat and helmsman, which cuts the motor if the helmsman falls overboard. Cooling System. Rotor of the impeller pump (cooling system) of an outboard motor The most common type of used on outboards of all eras use a rubber impeller to pump water from below the waterline up into the engine. This design has remained the standard due mainly to the efficiency and simplicity of its design.

One disadvantage to this system is that if the impeller is run dry for a length of time (such as leaving the engine running when pulling the boat out of the water or in some cases tilting the engine out of the water while running), the impeller is likely to be ruined in the process. Air cooled outboards Air cooled outboard engines are currently produced by some manufacturers, these tend to be small engines of less than 5 horsepower. Outboard engines made by Briggs & Stratton are air-cooled Closed loop cooling Outboards manufactured by Seven Marine use a closed-loop cooling system with heat exchanger.

This means saltwater is not pumped through the engine block as is the case with most outboards but still has to be pumped through the heat exchanger Other Outboard Motoring Method. Vietnamese-style 'Shrimp Tail Outboard Motor' Schematic. In Vietnam and other parts of southeast Asia a long-tailed motor design is used. In Vietnam these they are called 'May Duoi Tom'(Shrimp Tail Motor).

The outboard motors, which can be smallish air-cooled or water-cooled gasoline, diesel or even modified automotive engines, are bolted to a welded steel tube frame, with another long steel tube up to 3 m long to hold the drive shaft, driving a conventional looking propeller. The frame that holds the motor has a short, swiveling steel pin/tube approximately 15 cm long underneath, to be inserted into a corresponding hole on the transom, or a solid block or wood purposely built-in thereof., This drop-in arrangement enables extremely quick transfer of the motor to another boat or for storage - all that is needed is to lift it out. The pivoting design allows the outboard motor to be swiveled by the operator in almost all directions: Sideways for direction, up and down to change the thrust line according to speed or bow lift, elevate completely out of water for easy starting, placing the drive shaft and the propeller forward along the side of the boat for reverse, or put them inside the boat for propeller replacement, which can be a regular occurrence to the cheap cast aluminum propellers on the often debris-prone inland waterways. This design is utilized to propel. Manufacturers.

USA - Up to 5 hp. Hong Kong., a division of - USA - Up to 300 hp.

China. Japan - Up to 250 hp. / - USA - Up to 400 hp. (now Tohatsu). China. Italy - Up to 250 hp.

USA - 3 models rated up to 627hp utilising a sourced V8 supercharged power-plant. Japan - Up to 300 hp. Japan. Electric outboards. Zomair. Japan - Up to 425 hp Former manufacturers. (defunct).

(folded into ). (no longer manufactures outboards) See also. (inboard/outboard drive) References.