Yamaha EF2000iS front viewThe Yamaha EF2000iS is one of the most popular portable inverter generators on the market.  Yes inverter generators are more expensive than standard portable generators.  And compared to a standard 4000watt generator, you often get half as much power for 2-3 times the cost.

Do the benefits outweigh the cost?  Read on.  You are the only one who can make that decision.  The benefits are that for delivering 2000 watts peak power, this inverter generator is much quieter, lighter and fuel efficient than a similarly powered non-inverter generator.

Inverter generators are the choice for powering sensitive electronic equipment, including computers.  They deliver AC power in the form of pure sine waves which are cleaner and more reliable than most generator power sources.  For supplying power to emergency medical equipment, I would consider nothing else.


Table of Contents
(click a title to jump ahead!)

1. Power Considerations – Wattage
2. Engine Type and Fuel Considerations
3. Starting Mechanism
4. Oil Usage Considerations
5. Outlets and Meters
6. Noise Level – Portability
7. Warranty
8. What’s in the Box
9. Dimensions/ Weight
10. Pros and Cons
11. Consumer Reviews
12. Price
13. Summary

You need to determine if the price to power ratio is more important to you than the price to features and benefits ratio.  You can check out the current price for this Yamaha inverter generator to see if you want to even consider it by clicking on the Amazon button above.

While you’re there, take a look at the customer reviews.  They are overwhelmingly positive with over 235 reviews of 5 Stars.  It is no secret that the Yamaha and the Honda inverters are the top of the line.

I like to look at it like buying a car.  Yes any car will take you from point A to point B, but I still want all the car that I can afford.  You buy the best car or you buy the Yamaha, and you will not regret the quality that you own.

Check out this article on this website for an explanation of how inverter generators like this Yamaha work.  The great thing about inverter generators is that they run at power related to the load required.  That is, if you’re only using a portion of its 1600 watt running watts, the engine will run based on the load put on it.  That makes for the quieter aspect and better fuel efficiency.

For light use, one or two at a time appliance applications, this inverter generator could be just right for you.  Yes, this unit by Yamaha is CARB compliant meaning it is available for sale and use in California.
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The Review…

Power Considerations – Wattage

At 1600 watts rated AC output, and 2000 watts maximum AC output, this is NOT the one that you want to run multiple devices at the same time.   If you hook this model to another of the same model (with an available special cable), yes you can double the power to get up to 3000 running watts, but may not like the expense that two will cost.

For most, this is a carry and use generator and not necessarily for power outage needs.  If you hooked up your refrigerator to it, you may not be able to use it for anything else at the same time.  And of course you’ll want to consider a different generator if you want to hook up to your home’s power.  You’ll want at least 5000 or more watts to connect to your home via transfer switch.

This is the handy, portable power source that you might take camping or tailgating, or to power the creature comforts outside of RV needs.

You will get 13.3 amps at the running 1600 watts and 16.7 amps with it running at its full output.  As with all US generators you are getting 120V, single phase 60Hz.  Check out the handy table on this site to see what and how many devices you can expect to power with this Yamaha unit, or portable generators in general based on wattage.

The Inverter system is equipped with Pulse Width Modulation (PWM) control — which produces a pure sine wave to run devices with built-in microcomputers or microcomputer-controlled electric tools.  See the article on inverter generators for an explanation of pure sine waves vs. block waves.

Essentially cleaner power in pure sine waves means that you’ll be able to confidently power delicate machinery without having to worry about the damage caused by unrefined energy.

If you need extra juice, this model has you covered—a convenient parallel function lets you connect two generators to deliver up to 30 maximum amps.

This Yamaha model has TwinTech™ capability — You can hook up two EF2000iS for 3000 watts, and 25 amps of running power and 3600 watts and 30 amps at maximum power (requires an accessory cable available at extra cost).

dual Yamaha EF2000iS hookup

Economy Control Switch

A nice benefit of this inverter generator is the economy control switch.  When this is turned on, the economy control unit regulates the engine speed according to the connected load.  The results are more economical fuel consumption and less noise.  Compare this to a standard portable generator which runs at a minimum decibel level and the noise increases when more load is put on it.

When the switch is off, the engine of the Yamaha inverter generator runs at the rated 4500 rpm whether a load is connected or not.

Note, when powering appliances with larger starting watt requirements, the economy control switch should be turned off so that the surge of necessary watts can be accommodated.

On the power panel an AC pilot light comes on (green) when the engine starts and starts to produce power.

The overload indicator light (red) comes on when an overload of a connected electrical device is detected.  It will also come on when the inverter control unit overheats, or when the AC output voltage rises.

If this happens, the AC protector (breaker) will trip, stopping power to the generator to protect the generator and any connected devices.  The AC pilot light will go off while the overload indicator light will stay on.  Note that the engine will NOT stop running but the electrical power will stop.
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Engine Type and Fuel Considerations

battery charging Yamaha EF2000iSAs mentioned, this Yamaha line of inverter generators is CARB Compliant.  Meaning that it meets even strict California Air Resources Board and Environmental Protection Agency standards for low emissions.  According to the Yamaha website, these generators have the longest emission engine durability ratings issued by the Environmental Protection Agency and the California Air Resources Board.

The engine uses a CDI ignition system (capacitor discharge ignition aka thyristor ignition), which is used in most small engines and basically means that it is delivers quick current to the spark plugs for use in high engine speeds. The recommended plug type for replacement is BPR6HS (NGK)

The 4 stroke engine has 79cc displacement in its OHV (overhead valve) design.  Its Smart Throttle varies the engine speed based on the load and is activated with the Economy Control Switch.   Its OHV engine runs reliably and dissipates heat efficiently, allowing for both a long life and optimal fuel consumption.

The engine includes a steel camshaft and valve train components.  It has a cast iron cylinder liner which provides long life and excellent heat dissipation.

The 1.1 gallons (4.2L) fuel tank is equipped with a fuel gauge for determining how much fuel remains.  At a relatively small volume fuel tank, it can be difficult to “eye-ball” the fuel level which is where the fuel gauge comes in handy.  A couple of reviewers stated that their fuel gauge was useless and one of the few complaints in this very popular model.  When the gauge doesn’t indicate “full” you can tend to overfill.

The fuel cap has an on/off air vent which must be on to allow fuel flow to the carburetor.  This in combination with the fuel cock knob on the control panel can be used in combination when you are burning out the fuel for storage or emptying.  There is a screw to remove on the carburetor float tank that is accessible only after removing the side panel from the generator.

There is no fuel tank drain ability on this unit other than draining with a commercially available siphon, or the old fashion tipping of the unit on its side to drain from the fuel cap opening (not recommended).

Smart Technologies for Optimal Fuel Efficiency

long running Yamaha EF2000iSThe EF2000iS is exceptionally fuel efficient, able to run for up to 10.5 hours without refueling when in Economy mode.

With its Smart Throttle Load feature, the generator is able to dynamically adjust engine speed depending on output, resulting in greater overall fuel efficiency. The generator also features an exclusive dual coil alternator stator, which lowers engine speed and reduces total fuel consumption.

It has an automatic warm-up benefit, meaning that it increases engine speed during cold starts to handle high power demand appliances right away.

The Auto-decompression system reduces compression for easier starting.
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Starting Mechanism

This unit, as do most smaller inverter generators has a manual recoil start.  Perhaps due to its auto-decompression system, most report that this unit starts easily with one or two pulls.  No one likes to call their portable generator one of their pieces of exercise equipment!

When following the easy procedure below, you should be happy with starting capability.  Considering starting the generator is the most frequent thing you’ll do with ANY generator.


  • Economy control switch off.
  • Air vent on fuel cap on
  • Fuel cock on
  • Engine switch on
  • Pull choke fully out (not necessary when engine is warm)
  • Pull recoil briskly.
  • Under most conditions (cold start) let engine run for 3 minutes
  • Can turn economy control switch on.


  • Economy control switch off
  • Disconnect electrical devices
  • Engine switch to STOP
  • Fuel cock knob to OFF
  • Air vent to OFF

Remember to always ground any portable generator before use using the grounding terminal – connect to earth line to prevent electric shock.  This is recommended with all portable generators, standard and inverter types.  However, it is rarely the case in practice as most have a neutral ground bonded to the frame.

camping with Yamaha EF2000iS
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Oil Usage Considerations

Yamaha recommends 10W-30 oil for most ambient conditions.  The oil that you’ll need is not included, so have some handy when you use it for the first time.  The oil reservoir hold .42 US Quarts (.4L).

You won’t have to worry about engine damage due to low oil levels.  An oil-watch warning system constantly monitors oil levels and lets you know when an oil change or addition is needed.  This adds peace of mind, although you should always check the oil level with each use.  You’ll want to avoid costly repairs and minimize down time by never running the unit without the required oil.

There is a low oil warning light on panel the electrical panel which will glow when you need to address the oil level.

Yamaha EF2000iS backThe oil fill cap is accessible only after removing the four screws allowing you to take off the back plastic panel which encases the generator.  You’ll need a funnel (not supplied) to fill the oil reservoir.  Be careful not to overfill with oil.  This is an encased inverter generator and cleaning up oil that ends up in the unit rather than through the open frame and onto the ground would be a chore.

There is no oil drain plug.  To remove the spent oil, you must tip the generator and catch the oil in a pan.  When new, you may want to change the oil after 4 to 6 hours of run time, rather than the recommended 20 hours.  It’s not that difficult and if there is some debri in the system, it’s better to get it out early on.
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Outlets and Meters

control panel Yamaha EF2000iSOn the convenient front panel of this Yamaha unit you’ll find the easy access centralized controls.  There are the warning and operating lights, on/off switches and fuel controls mentioned earlier.  What is noticeably missing which is on nearly all non-inverter portable generators is a volt meter.

It is here that your find the receptacles for the Twin Tech (parallel running terminal) for hooking up another EF2000iS unit for increased power.

There are two AC receptacles providing 120V (NEMA 5-20R) and a circuit breaker.

For added convenience, you are able to recharge batteries with its 8A 12V DC output, making it ideal for RV, auto, and boat owners. For this there is a DC receptable.  The cord is supposed to be included in the box when you purchase the unit.  There is no mention of it in the included manual.  If it does not come in your box, and Yamaha doesn’t give you one, you may have difficulty finding the cord.

The DC protector (breaker) will trip when hooked up to a device operating above the rated flow.  This is great when needing to charge a car battery per the directions below.  If you have a stand-alone battery charger, you might opt for that since this method does not automatically shut off or slow to a trickle.

Charging battery

  1. Start the generator engine.
  2. Connect terminals to battery
  3. Turn economy control switch to OFF
  4. Make sure dc protector is on.
  5. Note: you must check for charging manually by checking specific gravity of electrolyte in the battery.  (usually between 1.26 and 1.28)  Check every hour.

It would be nice to have automatic shut off like with a standard battery charger.  Why not just plug in your battery charger in to the AC receptacle?
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Noise Level – Portability

This is one of the quietest inverter generators on the market due to its super-quiet muffler for quiet operation.  It uses noise reduction technologies to ensure the quietest operation possible. Featuring a special sound-blocking design, the generator has noise-absorbing glass wool construction.  This helps dampen noise even during heavy operation.

The decibel rating comes in at a very quiet 51.5 dBA at 1/4 load, tested at 7 meters.  The range is only up to 61 dBA.  It’s so quiet that you can have a conversation near one and may not realize it is running.

Granted that’s only producing 400 watts at 1/4 load, but consider a standard portable generator with a 2000 watt peak power.  Its decibels would be in the high 60’s at this load because they do not power down.  The engine revs at its minimum even with low load. Consider that the Decibel scale is exponential.  That means that an increase in 10 decibels from 50 to 60 means that it is TWICE as loud.

Along with this unit’s super-quiet muffler and vibration-isolating feet, noise is kept to a minimum.

The muffler contains an USFS-approved spark arrestor.  Great choice for providing the creature comforts while camping.

Ergonomic, User-Friendly Design

Yamaha EF2000iS quiet operationThe EF2000iS has a compact, portable and retro-modern design. It weighs a mere 44 compact pounds, making it for most people, easy to transport without wheels.

It is very compact (2.2 cu.ft.) which makes it easy to store and transport.  Its ergonomically designed handle is comfortable and won’t leave stress marks on your palm and fingers when carrying it to your destination.

It is suggested that when you transport in the back of a pick-up truck that you secure it well.  Having a small footprint and being somewhat tall, it will tip over easily.  If it tips over, when you start it, it may smoke heavily until the oil burns off.

It has easily detachable side panels not only keeping out the dust and dirt, but also making for easier serviceability of the important components.

It is no wonder that the Yamaha EF2000iS (and inverter generators in general) is a favorite among campers and light duty do-it-yourselfers.
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Yamaha provides a great warranty on their inverters.  They are backed by a limited two-year warranty that covers the entire generator for defects in parts and workmanship for three (3) years.

Recommended maintenance is pretty standard for portable generators.  This inverter type generator has the inverter technology that would require authorized repair should your need it.

  • Spark plug clean/replace 6 mo/ 100 hours
  • Engine oil replace 6mo/ 100 hours (initially after 1 mo/ 20hours)
  • Air filter clean/replace 6mo/ 100 hours (more often in wet or dusty areas)
  • Muffler screen clean or replace 6mo/ 100 hours
  • Spark arrester clean or replace 6mo/ 100 hours
  • Fuel filter clean or replace 6 mo/ 100 hr (sits in opening of fuel tank)
  • Crankcase breather hose 12 months/300 hours
  • See dealer for maintenance on cylinder head, valve clearance

The maintenance instructions and general operating and safety instructions are very well explained with illustrations in manual.  There are instances of the English being written as a second language (presumably Japanese), but this is not as bad as some I’ve seen.

Yamaha EF2000iS on the water

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What’s in the Box

  • Yamaha EF2000iS
  • Instruction manual
  • DC Battery Charging Cord
  • There is no oil, no funnel, no wheel kit, no tools

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Dimensions/Weight of the Yamaha EF2000iS


  • 19.3 inches
  • 11.0 inches
  • 17.9 inches


  • 44 lbs. (20 Kg)

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Pros and Cons

pro iconPROS:

  • fuel efficient – with economy mode switch
  • CARB compliant
  • smart throttle for operating with reduced load
  • automatic warm up – for quicker power from cold start
  • automatic decompression system – for easier start
  • quiet operation – 51 to 61 dBA
  • dc capability to charge 12V
  • expandable connectivity for hooking to another – TwinTech™ capability

con iconCONS:

  • oil not included
  • no gas drain – must siphon out
  • no oil drain plug – must tip the unit
  • 12v charging plug replacement difficult
  • can tip over in transportation

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Consumer Reviews

The customer review are overwhelmingly favorable for this Portable Inverter Generator.  In fact in nearly 300 reviews on Amazon.com, over 230 award this unit 5 Stars.  Add the 4 Star reviews and over 90% rate this inverter generator 4 or 5 Stars!

With the overwhelming popularity and high ratings of this unit, you can rest assured that you will not regret choosing this inverter generator.  Just be sure you know your power needs.  If the features and price combination match for you, you can’t go wrong.  The fact that it remains a bestseller over the years shows that consumers are happy with this generator and are not afraid to tell others.  Not only does it sell well, but the many users who don’t mind shelling out a good chunk of change for another one to use in tandem tells you something.

Users love the dependability and ease of use.  Many reviews praised the generator as exceeding their expectations.

Read more consumer reviews directly from Amazon here:  Yamaha EF2000iS Portable Inverter Generator Reviews

Average Rating 4.8 Stars

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The price of this model varies depending on where you buy it but Amazon tends to have the lowest price.

Check current pricing discounts:


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I can confirm that the Yamaha EF2000iS is all that it’s cracked up to be.  The defect rate is VERY low.  It compares nicely to the gold standard.  The similarly sized Honda inverter portable generator.  If you want the features that this generator has, you will be happy with this one.  For mid to small needs, this works fine.  Remember it is upgradable by hooking up a second unit with the connection cord (separate purchase).

Hooking two of these up will give you the ability to provide for most of your home’s power needs in an emergency to power multiple devices during a power outage, but I don’t recommend this.  And they can of course be disconnected and used separately.

There are 200 reviews on Amazon, and the majority of them give this model a 5 Star review.
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Filed under: $500 - $999ReviewsYamaha