Yamaha EF2000iS Portable Generator Review

yamaha-ef2000is-3d view

Yamaha EF2000iS Generator

The Yamaha EF2000iS portable generator is lightweight, fuel efficient, ultra quite, stylish, and comes in a the usable 2000 watt size range. It’s one of top selling portable generator on Amazon.

For general all around use this “two AC plug” and DC capable generator is a great choice for many folks. With a 2000 watt range, you will be able to power your household appliances if needed, use it to tailgate and can run a few slow cookers  or a couple of power tools all at the same time.

Power Output and Generation

The Yamaha EF2000iS generates power with a smooth running unleaded gas powered 79cc overhead valve (OHV) 4 Stroke Yamaha engine which drives an inverter generator providing the best form of power output. The Inverter system uses Pulse Width Modulation (PWM) control producing pure sine wave energy allowing you to power more sensitive electrical equipment without power spikes or phase changes.

Because it rates a 3 of 10 for the California Emissions Rating and therefore is CARB Compliant making it a great option for your portable generation needs.

The rated output is 1600 watts AC, with a maximum of 2000 watts providing 13.3/16.7 amps @ 120V respectively. When figuring power usage you have to account for a power factor and efficiency. Which means you take the wattage times power factor to get maximum wattage available for your rated watts. It is possible to use both DC and AC power, but the total wattage must be below the rated output (1600W)

An electrical overload breaker is also included, to prevent generator damage in case of an unexpected overload.

Video Summary Review:

Figuring usable watts: Example if your drill has a .85 power factor your available rated watts are .85 x 1600 = 1360 watts. If you also have an efficiency number you have to multiply by that again. 85% efficient would 1360 x .85 = 1280 watts. Not understanding this requirement has caused several people to under estimate the watts needed.

DC power is 12V at 8 amps which adequate for charging car batteries. (cables included)

A nice feature with this generator is the Smart Throttle Load capability. This feature provides an ability to automatically regulate engine speed subject to output need, thus providing greater overall efficiency and fuel savings. This is possible through the the exclusive dual coil alternator stator which enables lower engine speeds resulting in reduced gas consumption and quieter operation.

Fuel Type and Noise Levels:

The Yamaha EF2000iS uses standard Unleaded Gas and has a capacity of 1.1 gallons (4.2L). Octane of (R+M)/2 of 86, basically known as regular gas, and can be lowered a point or two for higher elevations. 

Oil requirements: Because the generator uses a standard 4 stroke engine there is no need to mix oil with the gasoline. Out of the box the generator does not come with oil, so your first task is going to be to go through the process of removing the case to add oil. You’ll need to pick up some SAE 10W-30 or 10W-40 oil and add 0.42 Quarts (just under a pint) (.4L) through the oil port.

Although some like to pick up just the right amount of oil, I’d suggest that you have some extra on hand when needed. Also see the comments below on the oil sensing system.

The engine is very fuel-efficient on this generator and the gallon plus of gas will allow about 6 hours at full load to an average of 10.5 or even 12 hours at intermediate loads.

One top feature is the Noise Reduction for very quiet operation.

The engine is equipped with an extremely quiet muffler which is an USFS – approved spark arrestor. The noise level is 51.5 dBA at 1/4 load which is well below the background noise which can typically be 60 to 70 dBA. At full load you can still talk with your friends at normal voice levels at around 5 or 6 feet away. NICE!

Known as sound blocking design the construction uses glass wool as the noise dampening insulation which is very effective at full operation. Additionally it is equipped with vibration isolating feet to eliminate noise that might be caused if the generator were used on a more flexible surface.

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Dimensions and Weight

The EF2000iS is around a foot square on the floor with a foot and a half in height (Overall dimensions (L x D x H): 13.3″ x 11″ x 17.9″. This translates to 1.5 cu ft but Yamaha indicates it requires 2.2 cu. Ft. space with a few extra inches of space as margin.

Without gas, the generator is 44 lbs. and with gas about 50 lbs. A healthy person should be able to lift it and move it around without to much effort.

Typical Uses and Needs

This Yamaha Portable Generator is the perfect size for quick and reliable power for any number of uses. Tailgating at your favorite event this unit could easily power 3 or 4 slower cookers. or a small hot plate. It’s portable enough for camping to power up some appliances or lights. It’s small and stores easily in your RV and for charging up various batteries for your boat or motorcycle. If you’re a handy man or have a need for electric power tools this is an ideal generator for those small tools.

One user was able to run 3 crock pots at about 300W, a medium large LCD TV, satellite receiver, and a small stereo. He was able to run about 7 hours on one fueling at full capacity.

Display & Control Panel, Start-up

Yamaha EF2000iS Control Panel

Yamaha EF2000iS Control Panel

The control panel has direct access to all features and it’s push button easy. They are all centralized on the right side of the panel.

Control panel has an Oil warning light which lets you know if its low on oil. Big note here, the generator will shut down if it senses the oil level is below a certain level. (See Cons below for user experiences.)

For the initial start up, the control panel has an engine switch for on/off, fuel cock knob for easy control on fuel to the engine and a choke for start-up. Operation note: Need to open fuel cap vent prior to using and then close when finished.

For operation it has an AC pilot light for indicating the output and an overload indicator light if you are trying to pull too much power,

For output you have two AC receptacles and one 12V DC receptacle with a DC protector breaker.

A unique feature is the Twin Tech (parallel running terminal) right there at the panel allowing you to hook up a second generator for greater output.

And last is a Ground (Earth) terminal for connecting to a ground electrode in the earth which is a fault prevention measure to protect you and the machine.


The generator uses a recoil rope (pull rope) starting method. Like with many of the newer lawn mowers the improvement in starting is very responsive due to the auto-decompression system. It simple reduces compression and makes starting nearly effortless. Reports from most users indicate one to three pulls to get it started and depends a lot on if it was setting dry or recently used.

Below are the steps to starting and starting the Yamaha EF2000iS generator.

Start Up:

  1. Turn economy control switch to off
  2. Open vent cap knob
  3. Turn on fuel cock knob
  4. Turn on engine switch to red
  5. Pull choke knob
  6. Pull recoil starter
  7. As engine warms up push choke back in.
  8. After warm up turn economy switch back on. (note that if you forget and leave it on, it will not operate until the engine is warmed up. which is 3 to 5 minutes.)

Shut Down:

  1. Turn off economy control
  2. Disconnect electric devices
  3. Turn fuel cock off (let engine run dry if going to storage)
  4. Turn engine switch to stop
  5. Turn fuel cap air vent to off.

Tips for storage: If you’re going to let the generator sit for a while you can turn off the fuel cock and let it burn up the fuel in the carburetor. For long term storage you’ll want to drain the system or add fuel stabilizer.

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Additional Features

Here’s a list of additional features that make this generating unit a top seller.

  1. Yamaha generators have the longest emission engine durability ratings issued by the Environmental Protection Agency and the California Air Resources Board.
  2. Fuel gauge allows fuel level to be seen at-a-glance.
  3. TwinTech for more power

    TwinTech for more power

    TwinTech™ capability allow you to connect two EF2000iS’s for 3600 watts, 30 amps of maximum power (requires accessory cable available at extra cost) This is nice if you’ve got a device over the individual rated load. However, if you’re driving several separate devices you’d probably be better off using them individually.

  4. Yamaha’s Oil Watch Warning System will help prevent engine damage from low oil, however, the sensitivity on this one can cause you to shut down prematurely. Always be sure to check the level often.
  5. OHV engine – Includes steel camshaft and valve train components and cast iron cylinder liner – Efficient, reliable, powerful providing long life and excellent heat dissipation.
  6. Auto warm-up increases engine speed during cold starts and gives you assurance that it’s being done per manufacture recommendations.
  7. Comfortable grip handle makes it easier to move and store.
  8. Easily detachable side panels which makes it easier to service.
  9. Rubber vibration isolation feet – Absorbing feet for smooth operation and noise reduction

Add to Cart>> Yamaha EF2000iS 2,000 Watt Portable Generator

Care and Maintenance and Use


Connect the ground lead of the machine to the ground (Earth) terminal and connect the end to the ground electrode buried in the ground. This is a condition of warranty and to prevent shock when using the generator.

Turn off your devices before plugging them in to the generator.

For DC charging you will not use the economy control, make sure it is turned to off.


Be sure to carry the generator only by its carrying handles

Do not use in wet condition such when it is raining or snowing or with wet hands.

One problem is that folks sometimes try to put the generator tucked away from site, but you need to operate it in the clear for ventilation and heat dispersion so don’t cover it with any objects either. The general rule is to provide a 3 foot clearance area to maintain airflow and good cooling.

Do not connect the generator to commercial power outlet as this can cause problems with the electrical service and potentially destroy your generator.

Avoid connecting the generator in parallel with any other generator, follow only the guidelines for the dual setup.


Periodic maintenance is a must with any generator that gets use. Here are the guidelines promoted by Yamaha and in general or good practice.

Pre-operation – check fuel, fuel hose, and engine oil. Generally look over your unit to make sure everything looks good.

Check air filter, muffler screen, spark arrestor and change your engine oil and clean the spark plug every 6 months or 100 hrs of operation

Yearly or at 300 hours expect:

  • to clean or change the fuel filter and check the crankcase breather hose for cracks. Replace as deemed necessary.
  • decarbonizing the cylinder head, adjusting valve clearance and checking all fittings and fasteners. This one thing that may need to be done and is often overlooked until the until the engine starts to perform poorly

With heavy use these are things you can do when spring cleaning or even getting ready to store your unit if it’s not going to be used for a while. You will want it to be running smooth if you have an emergency situation.

Of course all these procedures are covered in the Users Manual. Take the time to make sure everything is right with your machine. Yamaha has provided some great tips for their power generators when storing them for a longer periods.

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Warranty and Repairs

3 year warranty for personal use and 2 years for commercial. which is an outstanding warranty for mechanical items like generators.

The Warranty:

  • Starts at date of purchase
  • Must be for private, non-commercial use from an authorized Yamaha consumer generator dealer in the continental United States.
  • If utilized for commercial or rental applications the warranty period will be one (1) year
  • Warranted against defects in material or workmanship. Any replaced part is only good to the original warranty period.
  • Must use a authorized Yamaha consumer generator dealer for warranty service. It will be Yamaha’s (dealers) opinion that any device is defective and that is is due to faulty workmanship or material. It will be replaced/repaired free of charge if so judged.
  • Replaced parts become property of Yamaha Motor Corporation U.S.A.


Includes any failures caused by using or installing parts or accessories that are not qualitatively equivalent to genuine Yamaha parts. Also using in a manner which causes abnormal strain, is neglected, was abused, didn’t provide proper maintenance, or was by damaged by accident or collision.

SPECIFIC EXCLUSIONS include parts replaced due to normal wear or routine maintenance.

The Yamaha Service network isn’t as large as some of the other brands and can cause you considerable time and expense to visit them.

Consumer Comments

This unit is the number one rated portable generator on Amazon. As of this writing it was getting a 4.7 out of 5 starts. 92.5% were giving it a 4star or better rating.

Customers have touted this as high quality generator with a stylish design. It’s light enough to be easily handled and used.

What has been interesting is that the “quiet” feature is getting a good deal of chat here with some saying that the normal conversation can be done while close to the machine when operating. High marks on the running silent scale. Many users have commented on just how quite it is and have come back after a couple of years of ownership to say so. They are also extremely happy with the reliability and lack of problems.

On the negative side less than 6% of customers were having problems.

In a few instances of what would be considered poor housing cover construction and most were commenting on the warranty service. That is the network wasn’t as vast as some of the other brands so it was more difficult to get service. Also rather than make a replacement Yamaha preferred warranty repair on out of the box problems or with less than a few hours of use. Repair was also taking a long period of time.

Some folks that were complaining simply underestimated their wattage needs, so be sure to check our guidelines on how to get the right size generator.

A few were having issues with the carburetor and the needle value specifically being stuck and needing cleaning. This may be a poor quality gas supply so you may want to consider a small additive for cleaning if you think you’re getting poor quality of gas..

In general the customers are siting this as a very reliable machine and in a few cases where quality control missed the boat the service is not up to expectations. Even the respondents with high rating found customer service to be less than stellar. However, with a majority having such a good experience without having to go to service we’ll have to put it a the positive column.

One suggestion, if you are a bit mechanically inclined, is find the service manual and do the work yourself to save yourself from the headaches of service issues.

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Pros & Cons


  • Generally everyone agrees that this is a light-weight, small, and easy to use portable generator.
  • It has a high reliability rating and rated extremely well by a vast majority of users.
  • It’s super quiet and at low load you may forget it’s running. It has a great “economic mode” and will get 8 to 12 hours on a gallon of gas! In full power mode it’s still about 6 hours.
  • It’s CARB compliant and easy to start.
  • Handling up to 1600 rated watts makes it a good all around generator for the majority of small appliance needs.


On the negative side there are a few issues.

  • Low oil sensor can be very sensitive, so you need to ensure you are checking the oil before every use or it’ll shut down on you.
  • The generator doesn’t come with engine oil, so be sure to add that to your order. Or make sure you have 0.84 pints (.42 qts) available of 10-30 or 10-40 oil. Filling oil is by eye sight to the bottom of the filler hole which is likely to run out the filler hole. (bad to have spillage so use caution)
  • Occasionally there have been bad needle values and flooding which has caused a few problems with getting the generator operational.
  • Checking and changing the oil is messy and requires you to open the outer cover cases. Hopefully an updated design will make this easier in the future.
  • Because it’s small you’ll need to tie it down for transport as it doesn’t have a stable footprint for riding in the back of the car or trailer. Tucking it in between other more stable items will save any accidental damage which isn’t covered by warrenty.
  • You’ll want to lock it up to prevent theft, being this small and lightweight it’s and easy one to grab and go by the five finger discount artists.


Street price for Yamaha EF2000iS Generator is below $1000.

Since it is on the high end for pricing you’ll want to consider that you would plan on using this unit fairly often. There are lower cost options for emergency generation where you may only need a few times a year. But if you need portable power on a regular basis this is an ideal choice all around. The unit we reviewed is only shipped in 48 contiguous United States.

Why does the Yamaha EF2000iS generator cost more?

This is an inverter generator setup which is more costly to produce due to labor-intensive construction. It takes more to get a tight fit and time to make it right. In this case the insulation is a major factor in making it quiet and it takes more effort to make sure that it is done well. Generally speaking you pay more for the quality and effectiveness of the generator. That’s real value as opposed to what you get with a basic thrown together generator that is only focused on generating watts.

Check latest pricing here: Yamaha EF2000iS Generator at Amazon


There are a number of accessories you you’ll may need or wish to have when picking up this generator: (click image to add to your amazon cart)

  1. Foam filler Oil – Recommended Oil for engine.
  2. 5 gallon CARB Compliant gas can – This is just a good idea to have a CARB compliant storage for your gas.
  3. Powercord – You’ll want to be sure you can reach to your appliances and tools outside the noise area and inside the house if it comes to it.
  4. Yamaha Deluxe Hour Meter/ and or Tachometer – although not necessary this is nice for monitoring your usage and maintenance schedule.
  5. Funnel for both gas and oil to reduce any spillage and ease of filling.
  6. Adapter for mess free oil changes
  7. Yamaha Cover fits perfectly for the unit and keeps the dust off
  8. Twin tech cable is needed if you’re looking to use two generators.
  9. Appliance Load Testerfor finding out exactly your device power usage or need.
    Yamaha ACC-0SS58-40-44 Reliance Control Am/Watt Appliance Load Tester for EF1000iS Yamaha Inverter

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The Yamaha EF2000iS is a top seller and highly rated by the users. It provides 1600 watts of rated power and will run several devices at the same time. The portability is excellent at about 45 pounds making it easy to move and the small foot print makes it an nonintrusive and easily stored generator.

A primary selling point is the quiet operation and push button easy control panel making it a favorite among the heavy users. The ease of use in starting, and having both AC & DC power is ideal for all occasions.

The many features all add up to make it an economical overall choice for everyday use whether your tailgating, working in the yard, or out roaming the wilderness.

This unit gets our highest recommendation.

Similar Generation Units:

The following Yamaha Generators are similar to the above but at different wattage sizes

1000 watts: Yamaha EF1000iS 1,000 Watt 50cc OHV 4-Stroke Gas Powered Portable Inverter Generator (CARB Compliant)

3000 watts: Yamaha EF3000iSE 3,000 Watt 171cc OHV 4-Stroke Gas Powered Portable Inverter Generator With Electric Start (CARB Compliant)

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