Choosing an outboard motor for a small PVC boat or a compact boat is always a search for a balance between weight, power and economy. Yamaha 8 For many years, he has been one of the leaders in the 8 horsepower class, offering a time-tested design, and boaters value this unit for its incredible survivability and ability to operate in the harshest conditions.
In this review, we will take a closer look at the technical details of the two-stroke version, which is most popular among anglers and hunters, and learn about the real fuel consumption, the features of the lubrication system, and why this engine is often called “unkillable”. Reliability Here it is combined with an affordable service price, which makes the purchase economically justified.
It's worth noting that the Yamaha 8 is often chosen as the main engine for lightweight aluminum boats or as a backup for larger vessels, and its weight makes it easy to carry the unit to one person, which is critical when launching from a sloping shore. Let's dive into the design details.
Technical specifications and engine design
The heart of the unit is a two-stroke internal combustion engine with a volume of 139 cubic centimeters. carburetorIt has a petal intake valve, which provides excellent traction at low revs. Electronic ignition system (CDI), which does not require adjustment of gaps, which makes life easier for the owner in the field.
Cooling is carried out by off-shore water through an integrated water pump. An important feature is the possibility of using the water. Yamaha 8 It's a salt water solution, because it's corrosive, although it's still necessary to wash it with fresh water after use, and it's only 20 kg, which is one of the best in the class.
The transom mount allows you to install the motor on boats with a transom height of 381 to 508 mm. Shifting is carried out manually, and the control can be both rumpled and remote (depending on the modification).
| Parameter | Meaning |
|---|---|
| Type of engine | two-stroke, 1 cylinder |
| Workload | 139 cm3 |
| Maximum power | 8bhp at 5000 rpm |
| Ignition system | CDI (electronic) |
| Weight (with screw) | 20.0 kg |
The secret of the durability of piston
The Yamaha 8 cylinders use a special nickel-phosphorus coating that significantly reduces friction and increases engine life compared to conventional chromium.
Lubrication system and fuel efficiency
One of the main features of the model is the lubrication system PremixThis means that the oil is not supplied automatically from a separate tank, but is mixed with the gasoline manually before pouring into the tank. The ratio is 1:50 for running and 1:100 for normal use using quality oils. Yamalube.
This approach has its pros and cons: on the one hand, the lack of an oil pump and a tank simplifies the design and reduces weight, on the other hand, it requires discipline from the owner, and if you forget to add oil, the engine will quickly fail due to the bully of the piston group.
The use of high-quality synthetic oil and accurate compliance with the proportions is a guarantee of a long life of a two-stroke engine.
As for appetite, Yamaha 8 It's very efficient, and at a cruising speed of about 30-35 km/h, fuel consumption is not more than 2.5-3 liters per hour, and this allows you to travel a long distance without refueling on a full 12-liter tank.
- 🛢️ Use only AI-92 or AI-95 gasoline with an octane number not lower than the stated in the instructions.
- 🧪 Carefully stir the mixture of gasoline and oil in a separate canister before pouring.
- ⛽ Do not store the finished mixture in the engine tank for more than 30 days to avoid stratification of components.
Operation: launch, break-in and control
The engine is manually started using a cable starter, and the mechanism has proven to be reliable, but requires proper handling, and before you pull the cord, you need to make sure that the motor is vertically mounted and submerged in water, or connected to a barrel of water.
The breaking in process is critical for the new unit, which takes 10 hours and involves operating at various speeds, not exceeding 70-80% of the maximum, during which time the piston rings and bearings are laundered, and ignoring this stage can lead to loss of warranty and reduced resource.
☑️ Plan of Action for First Launch
The control is rampelled, with a convenient rotating mechanism of gas. The gear lever has three positions: neutral, forward and reverse. The moves are switched on clearly, with a characteristic click, which gives tactile confirmation of the transmission activation even in noisy environments.
Compatibility with watercraft
The 8 horsepower is ideal for a wide range of inflatable and rigid boats, the optimal length of the hull varies from 3.0 to 4.5 meters. For longer vessels, thrust may be lacking, especially when fully loaded or on the current.
Owners of PVC boats with a length of 3.2-3.6 meters note that Yamaha 8 It takes the boat to plane with one passenger and a minimum load, and if the load increases, the boat goes into displacement mode, but confidently keeps the speed of 10-12 km / h.
When choosing a propeller, consider the type of boat. The standard 8-inch propeller works well on heavy boats, providing traction. For light inflatable sides, you can try a large-step propeller (9-10 inches) to squeeze out the maximum speed, but there is a risk of not going out on the planing.
Maintenance and typical faults
Despite its simplicity, the engine requires regular attention. The main enemy is poor fuel and water in the system. Regular replacement of the spark plug and cleaning of the carburetor will prolong the life of the engine.
⚠️ Warning: When storing the engine in the off-season, be sure to drain water from the cooling system, otherwise, when freezing, ice can break the cylinder block or pump body.
A typical problem for two-stroke workers is to coke the exhaust windows and silencer during long-term operation at low speeds (for example, when trolling), periodically you need to "burn" the engine, allowing it to work at high speeds for 10-15 minutes.
If the engine starts to stall or lose speed, first check the fuel filter-sludge and the state of the fuel diaphragm in the carburetor. These elements wear out the fastest and are inexpensive.
Comparison with competitors and final conclusions
There are many analogues on the market, such as Tohatsu or Hidea. Yamaha 8 It's a huge advantage because of the availability of service centers and parts anywhere in the country, and even if the original parts run out, you can always find quality analogues.
Competitors may offer slightly less weight or an electric starter as a base trim, but the reliability of a Japanese build often outweighs these arguments: The motor retains residual value and is easily sold on the secondary market.
⚠️ Warning: When buying a used motor, be sure to check the compression. value below 6 bar indicates serious wear of the piston group and the need for major repairs.
In conclusion, it may be said that Yamaha 8 It's a workhorse for people who value predictability and simplicity, it doesn't require complex maintenance, it's easy to repair and it allows you to move confidently on the water, and it's hard to find better solutions for fishing, hunting or cruising short distances.
When buying a used motor, ask the seller to demonstrate the work on water. No smoke (except for short-term start-up) and smooth sound are good signs.
Frequently Asked Questions (FAQ)
What is the best gasoline for the Yamaha 8?
It is recommended to use unleaded gasoline with an octane number of at least 92 (AI-92). The use of gasoline with a higher octane number (AI-95) is allowed, but is not strictly necessary if the carburetor is set correctly.
Do I need to dilute the oil if I rarely ride?
Yes, a 1:50 or 1:100 ratio is always observed, regardless of the frequency of use, but if the engine is idle for more than a month, the mixture in the tank can dissipate or oxidize, it is better to prepare a fresh mixture immediately before getting on the water.
Can I install an electric starter on Yamaha 8?
There is no electric starter as standard, and installing it yourself is extremely difficult and economically inefficient, and the engine design does not initially provide space for the installation of a starter and a generator of increased power.
What is the maximum weight of the boat that can withstand this engine?
The engine is able to bring to the planing boat with a total weight (with cargo and people) up to 350-400 kg. It all depends on the shape of the hull and length. For heavy keel boats, planing may not occur, but the movement will be confident.