Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

When disaster strikes, my deep freezer goes down. Is were can a find a discotion about genarators? Thanks.

I was going to suggest the same thing. Don't get me wrong, I'm all for a DIY solution when appropriate. But there's also a point where, to me, it's either not worth it, or I may make something less-robust when doing it myself. To buy an inverter of that size seems to be ~$130-180 or so (I'm sure there are less-expensive options, this is just from some quick eBay checking). Plus an engine, plus an alternator, plus coming up with a way to mount it all together.

A 3hp engine, as an example, gets you a max of 2,200W, if everything is 100% efficient. Or you can buy something that will put out at least 3,000W, and not need to worry as much about something not working properly, and perhaps damaging what you plug into it. If you have the engine, and you have access to a big alternator, etc, it may be a great solution. And it would certainly be an interesting project. I'm not saying there's no place for it. But in some cases I'd prefer a commercial solution.

Frankly, a Harbor Freight unit wouldn't be my first choice from a quality perspective, though the capacity/$ is tough to beat for being new. And their small 800W generator appears to get very good reviews, and is as little as $90. But keeping an eye on Craigslist may get you a larger, higher-quality used unit for less than a new Harbor Freight. I bought a 5500W Generac (also puts out 220V) for $175, with pressurized lube and an oil filter. Replaced a bad oil pressure switch and it's worked great since. There are better deals out there, but I still got more machine for less $ than HF. And I don't think I could have built anything for that price. Just my perspective.

a 3hp gas engine is really only going to produce 1500 watts on a good day not counting the huge conversion losses using a 12v alternator (which in and of itself is quite inefficient)  to charge an lead acid battery to feed a DC/AC inverter which is at best 80% efficient will produce when all is said and done about 1,000 of useable power.

A pressure lubed 5500 watt Generac is a nice generator.  I suspect its an 11hp engine on it.  Yes if you can find one that is cheap enough on CL especially if it has carb problems and the gen head is good I say grab it.

Correct, it has an 11hp GN-320 Generac engine. It sounds like the portable Generac units aren't held in the highest regard (they certainly aren't Hondas), but the price was good, and it kept me going during the October storm we had (fridge, furnace, lights, and also the pump for the sewer line, though I shut off the fridge & furnace when running the 220V pump).

The only issue it has is that it surges unless I give it half-choke. It smooths out nicely with the choke. So my assumption is that the carb is running lean (whether due to being partially clogged, or if that's just how it is with today's gas, I don't know). The carb is not adjustable. I'm having trouble trying to find a rebuild kit for the carb, however. It's a Nikki carb, 093302 or 093302A. And I'm hesitant to open the carb without knowing I can get a rebuild kit. I can run it with partial choke. I can't run it at all if I damage a seal or whatever and can't replace it

Is that one of those plastic carbs.   I had to do some work on my Brother in laws generator that had an 11hp briggs on it and it surged very badly most of the time and need 1/2 choke to run correctly.  It was really strange because it didn't do it all the time.  You could start it up and run it and it was fine, turn it off and 2 hours it was surging when you ran it.   It had the plastic carb with the clip on the float bowl. 

I opened it up and cleaned everything very well but it still did it.  I told him to run it at 1/2 choke when it acted up as he did  not want to spend the money for a new carb.

I am pretty sure the carb is metal, going from memory, and pics of the carb when I've been looking online for rebuild kits. It's a Generac-built engine (well, maybe actually built by someone else, but pretty sure it's not a Briggs), for reference. It's an older unit, ~2000 or so, I believe. The carb is ~$65, so I don't want to just try replacing it. I'm OK with running it with partial choke for now, but I'd feel better if I didn't need to do that.

bus708 wrote:
That's a lot of parts of unknown condition and reliability.  Seems like increased probability of things going wrong when you really need the power.  If this homemade generator is a back up unit of the main generator, that's fine.  From the description of all the components, the overall size is going to be 3 to 4 times the size of a generator of equal wattage, just thinking out loud.

Do you have a picture of your homemade generator?

I must admit to running a homebrew backup generator.  My backup generator is based on single cylinder 6hp diesel engine that was designed in England 1929. This engine has two huge flywheels each weighing 150 lbs and was originally designed as a hand crank start. the engine weighs about 600 lbs and belt drives a large (250lb) 4 pole 1800 rpm 4kw gen head  The engine and generator are mounted to a very large I beam frame which weighs about 275 lbs by itself

The engine runs along at a nice slow speed 650 rpm and just kinda of lopes along.  no screaming 3600 rpm. 
My generator is currently setup to run on 85% natural gas and 15% diesel.

My generator is connected to a manual transfer switch which powers 20 circuits in my home.  During a power outage I start the generator and just flip the transfer switch to gen and we again have power in the house.

Wow.... I would love to see that.

Do you have it geared up by the belts, so your 650 RPM on the engine gives you the 1800 RPM on the gen head? What do you mean, it's set up to run 85% natural gas, 15% diesel? Those two fuels sound so incongruous (at least to me) that it almost feels like you're pulling my leg. A gas and an oil, together? 1,000 lbs, and 4kw? Wow, you may win the lowest watt/lb award Sure would be nice and quiet, though (at least by comparison) spinning that slowly. Mine is pretty loud, roaring along at 3600.

I think it would be cool to take a big (~20+ hp) engine, maybe off something like a lawn tractor, run it down at 1800 RPM, and use it to spin either an 1800 RPM head, or alter the belt ratios and use a 3600 RPM head. The engine would be making much less than its rated power, but it would also be a lot quieter. A diesel is the obvious way to do that, but diesel engines are less common and more expensive, it seems.

Is yours one of the big Lister (?) setups I've heard about? Or something else altogether?

RedOctobyr wrote: Here are a couple of links to my Lister setup.  The belt on the 24" flywheel  powers a 8.7" pulley on the generator for a 2.76:1 ratio or about 1800rpm at 650rpm


http://www.youtube.com/watch?v=UfGjlHNX-68&feature=mfu_in_order&list=UL

http://www.youtube.com/watch?v=AwPPui8Fyi0

http://www.youtube.com/watch?v=LL2zUvQIIuY

Are those your videos, carlb? They are very, very cool. That is a great setup. Things that I loved:

- Big exhaust setup with expansion tank and automotive muffler, vented out through a wall (at least in one of the videos).
- Radiator plumbed in, with an overflow tank.
- Exposed pushrods (!)
- The air starter is fantastic. Air powers both the motor and the cylinder to automatically bring it in contact with the belt. Brilliant.
- Wild dual-fuel setup (again, in at least one video), with an electric valve for the natural gas, which is powered by the generator itself. Any loss of power means the gas valve closes automatically.
- Seems quiet. Certainlyl low RPM. Will probably run forever, from a durability standpoint.

As I was watching some of the videos, I kept thinking of Rube Goldberg. That typically has negative connotations, and I don't mean it like it that at all. I mean it as a compliment, because the narrator kept showing additional features, tweaks that were made, valves for this and that. The list appeared to just keep going. This was not a drop-it-in-and-go setup, it would appear. A lot of time has been spent to tweak & optimize, and tie it into the house and utilities. I assume that the dual-fuel setup would let you practically run indefinitely as long as you have natural gas. Even if the gas supply goes out, I'd expect this is pretty fuel efficient.

Can you start it by hand somehow? If the flywheels are 250 lbs, I expect you can't simply grab their spokes and give them a flick. I could see something going around on the inside of the flywheels, where the spokes meet the outer wheels. As if the ends of the spokes are not all the same size or something (there's also a white thing going around with the flywheels, maybe that's it). Is there something like a balance weight on there?

The biggest downside I can see may be that now I want one If your power goes out frequently, and you have the space, that must be great to have ready for action. Fantastic work on getting that all sorted out!