This website has all the data about the Yammie:
http://www.hayesequipment.com/yamaha_ge ... 1000is.htm
Informative YouTube videos from amateurs found on the net:
http://www.youtube.com/watch?v=rOc1cGdJiw4 Dude! it's .66 GALLONS, not .6 Liters!
http://www.youtube.com/watch?v=y6c3gLLagX8 Uh, you mean "Watts", not Volts.
I got this little Yamaha primarily for quiet overnite power to keep the refrigerator and chest freezer running during a serious power outage. 12 hours at 1/4 load on a full .66 gallon tank is unbelievable. So is 4 hrs at 900W. It also can be running "on line" in 5 minutes. I already have the excellent 3,000W continuous Honda EM3500 generator for the higher daytime power needs (microwave or stovetop + satelite TV + lights + freezer + kitchen refridge + ceiling fan), but the thrumming moan it makes is a just too loud for sleeping. A time when only the refrig + freezer + maybe woodstove fan need power. It also takes at least 10 minutes to move it, gas it up and hook it up. It's real heavy to wheel around too.
That's where this little gem comes in. Just got it Nov 30 and took it apart on the kitchen table before even starting it up. You'll see the yellow "No oil" tag in the pics. Why? Because every GD place I looked for the valve adjust specs refused to list it.
I'd have to buy the expensive manual now, instead of later, or try and coerce the Yamaha Service dept to look it up and tell me. Truthfully, the real reason is I wanted to see what's inside it and where the clearances were set by the factory production line. I found the typical tiny 4-stroke engine's minimal clearances:In: .05mm
Ex: .07mm
Then, for history and my own satisfaction, I broke out the camera, took these shots and added in the text with IrfanView:
The unit
The basics
Top view
Intake port
Valve gear-1
Valve gear-2
Valve cover
The side
Carb-1
Carb-2
Here's a pic of the Cut Away.
The alternator is the narrow one on the right side of that pic and it's part of the motor.
OK. Poured in the oil over the valve gear until it showed up in the filler opening, then put it all back together. No worries about a dry top end startup now! Even tipped the whole unit all 4 ways so every bearing would be flodded with oil. Added about 1/3rd tank of gas and got it ready to go. Because the gastank, carb bowl and fuel lines were bone dry, I knew it would take many pulls of the recoil start for the crankcase air pulses to oscillate the fuel pump diaphram enough to pump the required fuel, and it took 8. The carb is pretty high and the fuel pump check valves could stop any siponing, so the recoil is the easy way to prime the system. When it started I couldn't believe my ears! It was really really quiet!! Let it run until it warmed up and then it idled down. Then I tried some low power plug-ins like a 1/2" drill and a small 10" fan. They barely made it labor or change RPMs. It's a new motor, so I let it run while playing with the Eco throttle switch to vary the RPM's. Very impressive, with the quality feel and sound of an extremely well made, expensive machine. It's like Acura made it. You feel it just pulling the choke knob in-&-out (engine off). Smooth as silk and very solid. There's no clicking, ticking or clattering emanating from the running 50cc motor, electrically loaded or not. Definitely not made to a price point like all those under $200 Chinese models, or even the cheaper $500 1KW inverter models made by other familiar U.S. Mfgr brands. You get what you pay for.
After about 1.5 hrs runtime on a few shut down, cool off, start-up agains, I tried it on our medium sized Kenmore chest freezer in the basement. I turned freezer's thermostat to "Max" for my extended run test. It had been unplugged long enough to bleed down the pressure and the internal temp went from +9F to +17F. At full rated speed it reved higher and roared about 2 seconds for the compressor to startup, then unloaded. I thought it popped the electronic overload circuit, but the freezer was running. Activated the Genny's Eco switch and it went almost to an idle. The Kill A Watt power meter I plugged it into said there was a 120W draw. After an hour it was down to only 73W, with the compressor still eartest-to-chestwall confirmed to be running. Terminated test with -9.8F freezer internal temp. I carried it with 1 hand, still running, back up to the garage, marveling over the powerful gyroscopic forces it had at an idle. Plugged in an old 7.25" circular saw that took it to it's overload light flashing limits on the start-up, almost 3 seconds of it. Then the saw gradually went from fast speed to full speed with no more flashing overload light, implying wood cutting would have to be with a slow-n-light feed speed.
The final test was to start-n-run our kitchen's 21 cu ft Bottom-Freezer Amana Refrigerator (energy star compliant). The Yam Genny is supposed to be capable of 3 times the rated load (3 x 900W = 2,700W) for 3 seconds for start-ups of electric motors, so it should be able to do it. I already measured the fridge drawing 120W from the kitchen GFI outlet for the running Watts and just over 1800 starting Watts. The real world test is starting the freezer and refridgerator sequentially and leaving the Genny control on Eco idle overnite when the power is still out. It's a challenge because the freezer only has a compressor and the fridge has that plus the induction motor condensor fan. My other Genny, a brand new looking, 21 year old, much noisier EM-3500 Honda recently started both cooling appliances, several lights, DVR hardrive and a ceiling fan with one louder 2 second exhaust roar. On a 14 gage extension cord out the back door the little Yammie started that big kitchen refrigerator EASIER than the smaller chest freezer! I left it running 3 hours on Eco idle and it had no trouble starting it from low RPM's. Those tests put together tell me the little blue suitcase generator will do exactly what I got it for and then some. So far I am very pleased with it's quiet Mighty Mouse power and REALLY impressed with the brilliance of inverter generator technology!!
FYI: If you need a generator, spend the extra money and get the best "inverter" Genny $,$$$ can buy. It's a proven long term investment that WILL save your sanity, expensive frozen food, costly refrigerated items and give you TV with lights and comfort in ways the cold, darkened neighbors will hate you for. Savy operators know how to "off" the home's main breaker and safely back feed a 240V dryer outlet (in an emergency, of course
) so everything in the house works!! I spent a grand in 1988 for the premium grade EM-3500 Honda Generator and it never let us down . . . about a dozen very critical times!! 
No, I haven't lost it. I rode My F800-ST yesterday and today on errands and really liked riding it in the cold weather. Yes, I'm really jazzed about my little blue colored early Christmas present. Like the trouble free Made in Japan EM-3500 Honda from 1988, It'll be around a good long time!
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