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Low Speed Generators, Gasoline and Diesel

hoarder

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#1
By "low speed" I mean 1800 RPMs. Most, if not all newer generators run 3600 RPM because they are cheaper to produce.

All 4 of my generators are 1800 RPM and over 25 years old.

I bought this Onan gasoline 5 KW BGA for $300 not running. It had fallen off a trailer and was dented up, had to fabricate a new air filter and replace a control relay.
I live off grid so I've already put about 250 hours on it. It never fails to start even when it's +10 degrees F out. It burns about a half gallon of gasoline an hour.

These Onan 2 cylinder horizontally opposed engines are designed for RV's. When you find one it won't have a battery or gas tank. There is about a dozen different versions of this engine. http://www.perr.com/onan.html

I could convert it to propane, but the conversion would cost as much as the original purchase and gasoline engines are easier to start.

Sometimes people refer to gasoline generators as "gas generators". This is incorrect, gas generators run on propane or natural gas.
 

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hoarder

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#2
I recently found another Onan, this one in running condition showing 750 hours, it's a gasoline powered 6.5 KW NH model. $400.

It seems to run well, puts out voltage, I haven't put it under load yet. I changed the oil and filter and spark plugs and points (yes, EMP proof). I keep spare points and condensors. I wonder if I need to keep a spare coil, they are expensive and special.

Both of my Onans are capable of 240VAC. They can be wired for 120VAC only which means you don't have to worry about balancing loads. I may switch my house generator to 120 VAC only for this reason, I'll have to put a jumper in my distribution panel to make both sides common. I need to figure out if my wiring will carry the load first.

These flathead horizontally opposed Onans were available in both cast iron and aluminum blocks, both mine are aluminum. One thing about aluminum is that the valve seats are made of a different material, which holds up to unleaded gasoline, an important consideration in older engines. The cast iron blocks may have cast iron valve seats, if so, not too good with unleaded.

Onan made many different sizes of gasoline and diesel generators in the past, all the pre-Cummins (that's who bought them out) Onans were good. Unfortunately Cummins a$$holes don't support then very well.

My Onans are "exitor start" meaning the generator windings start the engine, no external starters. Later models had external starters.
Some people don't like these Onans because of all the brushes. Mine each have 12 brushes. The brushes really don't have problems, they are easy to get to and you can reach in and pull the brush leads and "snap" each brush to make sure it isn't sticking.

Both my Onans had automatic chokes, which is appropriate for RV installations, but they are not reliable and I changed mine to manual choke which is easy since they have manual override.
 

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TnAndy

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#3
Sweet.

I have a 16hp Onan on my Miller Bobcat welder, that also has 8kw on the generation part, but it's a "screamer"......3600rpm. Buddy of mine has an older, smaller, Miller welder with an 1800rpm Onan on it.....it just loafs along compared to mine.
 

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#4
18 months ago I bought an old 2 cylinder, air-cooled diesel 8 KW trailer mounted generator for $1200 in great running condition. It's a "Dyna" Winco generator head and an obsolete Italian Slanzi engine.
There are no parts available for these engines, not even filters. I fabricated a different set up so I can use easily available spin on oil and diesel filters.

It runs perfect, starts in cold weather and doesn't use oil.
 

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hoarder

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#5
Another pic of Slanzi:
 

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TnAndy

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#6
Heck, the generator head alone is worth what you paid, even if you had to stick another engine on it.

Check out THIS deal up the road from me. I'm sorely tempted to go buy it, but I just can't figure out HOW I'd use 55kw....ahahaaaaa

 

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#7
Heck, the generator head alone is worth what you paid, even if you had to stick another engine on it.
Kato, Lima and Winco are the best generator heads made, IMO. I already put 200-300 hours on it filling cisterns and irrigating food plots. It only uses a half gallon of red diesel an hour. It might last for years.
Check out THIS deal up the road from me. I'm sorely tempted to go buy it, but I just can't figure out HOW I'd use 55kw....ahahaaaaa

It seems that it's hard to find good old generators under 20 KW, when you go big there are deals everywhere.
There are a lot of good big generators made and since Cummins provides such poor support for Onan, other brands are worth equal consideration.
 

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#8
Last year I bought an old Hobart welder/generator. The generator on this model only produces about 2.5 KW, enough to run a grinder or chop saw.

It has a 2 cylinder air-cooled Wisconsin TJD engine, a heavy beast. These engines are much heavier than Onans of equal size, but Onan beat them out with the horizontally opposed design. One thing good about these Wisconsins is they have a magneto, even on one cylinder models. What that means is that at cranking RPM, it "snaps" and gives an extra hot spark which makes them easy to start. The "weak spark issue" which plagues many small older engines is not a problem on Wisconsins.

The welder is 200 amp but I doubt the little engine could carry that much, judging by the way it bogs down when striking an arc at 140 amps.

I only have $680 tied up in it including the 2 batteries (for exiter start) and new tires. The leads are probably worth half that much.
 

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#9
I'm not counting the Hobart/Wisconsin welder/generator as one of my generators, since I'm unlikely to use it for that except when welding, besides I have no idea how many RPM's it runs.

My 4th generator is my pride and joy. A Lister ST2 14.5 HP 2 cylinder air-cooled diesel turning a Lima 7.5 KW generator at 1800 RPM. I bought it as a basket case with the pistons and rods already removed.
 

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Jimfrancisco

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Onan made many different sizes of gasoline and diesel generators in the past, all the pre-Cummins (that's who bought them out) Onans were good. Unfortunately Cummins a$$holes don't support then very well.
Not just "Don't support them well", they are a plain rip-off for any part! I have Onan gennys all over the place - they very, very, rarely go wrong. Like 20,000 hours go wrong. But if it does? Jesus, Onan will bend you over for parts and they don't use lube! Still love them though, one of mine is sitting on 18,000 hours and still starts within three cranks!
 

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Not just "Don't support them well", they are a plain rip-off for any part! I have Onan gennys all over the place - they very, very, rarely go wrong. Like 20,000 hours go wrong. But if it does? Jesus, Onan will bend you over for parts and they don't use lube! Still love them though, one of mine is sitting on 18,000 hours and still starts within three cranks!
Are you getting those kind of numbers on horizontally opposed 2 cyl gasoline Onans or another model? Onan USED TO be a very good company.
This seems to be what happened to nearly all companies, a proud family builds it up, a couple generations later it gets bought out by Wall Street a$$holes who are only interested in next quarter profits and down the toilet it goes!
 

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#12
These air cooled Listers are reputed to run 20,000 to 40,000 hours between in frame overhauls. That's pretty amazing considering most modern diesels only go 5,000 hours on an overhaul. 40,000 is equivalent to one million, six hunred thousand miles on a car!

Nobody makes anything comparable anymore. Like Onan, the Lister company does little to support their older engines, parts are high priced when available. Fortunately there are quite a lot of aftermarket and used parts available.
http://www.diesel-electric.us/

I tore the engine down including the crank. The flywheel, which is on the floor next to the bellhousing weighs 108 pounds including the cast aluminum fan. Most 14 HP engines don't weigh that much complete!

It's now completely overhauled and has been test run on my workbench. The generator puts out voltage but I haven't put a load on it.
 

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#14
Your workroom looks like an operating room compared to my mess.
That picture was taken right after I built the shop last summer. It's a mess now. As our eyes get older, our vision in low light situations gets a lot worse, especially if we've been doing our share of welding. That's why I painted the shop and workbench white.
 

Jimfrancisco

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Are you getting those kind of numbers on horizontally opposed 2 cyl gasoline Onans or another model? Onan USED TO be a very good company.
This seems to be what happened to nearly all companies, a proud family builds it up, a couple generations later it gets bought out by Wall Street a$$holes who are only interested in next quarter profits and down the toilet it goes!
Yep, boxer engined Onans - mostly CCKs on gas or gasoline. I don't even treat them particularly well - use cheap oil but change it often, and load them RIGHT up to about twice the limit for an hour every now and again to make them huff, with no muffler.
Like you said, they used to be great - now they try and charge you $30 a set of points when the same part is $6 at NAPA!
Scumbags...
 

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#16
Currently I'm building a skid-frame for the generator and a 100 gallon diesel tank I bought used.
 

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