Reviving a $25 Generator

[Jennies Garage] found a used and abused inverter based generator in the clearance section of his local home improvement store. The generator had been returned on a warranty claim and was deemed uneconomical to fix. Originally $799, [Jennies Garage] picked it up for just $25. He documented his quest to get the device running with a trio of videos.

The generator had spark, but didn’t want to fire. The only obvious problem was the fact that the machine had been overfilled with oil. There was little or no compression, but that is not uncommon with modern small engines – many of them have a compression release mechanism which makes them easier to start.

With all the obvious problems eliminated, the only thing left to do was tear into the engine and figure out what was wrong. Sure enough, it was a compression issue. The overfull oil condition had forced engine oil up around the piston rings, causing them to stick, and snapping one of the rings. The cylinder bore was still in good shape though, so all the engine needed was a new set of rings.

That’s when the problems started. At first, the manufacturer couldn’t find the rings in their computer system. Then they found them but the rings would take two weeks to ship. [Jennies Garage] isn’t the patient type though. He looked up the piston manufacturer in China. They would be happy to ship him complete pistons – but the minimum order quantity was 5000. Then he started cross-referencing pistons from other engines and found a close match from a 1960’s era 90cc motorcycle. Ironically, it’s easier to obtain piston rings for an old motorcycle than it is to find them for a late model generator.

The Honda rings weren’t perfect – the two compression rings needed to be ground down about 1/2 a millimeter. The oil ring was a bit too thick, but thankfully the original oil ring was still in good shape.

Once the frankenpiston was assembled, it was time to put the repair to the test. [Jennies Garage] reassembled the generator, guessing at the torque specs he didn’t have. The surgery was a complete success. The generator ran perfectly, and lit up the night at the [Jennies Garage] cabin.

If you’re low on gas, no problem. Did you know you can run a generator on soda? Want to keep an eye on your remote generator? Check out this generator monitor project.

35 thoughts on “Reviving a $25 Generator

  1. Ahah, he fixed the generator’s motor – for a very snazzy return on outlay, indeed.
    When our little 2 KVA generator drooped to 190 Vrms (from 240), after around 25 years of heavy use, and two or three worn-out motors, I found that there’s only rotor & stator windings plus one “phase capacitor” in there – no electronics. But the capacitor markings had worn off. To dimension the required replacement, I substituted increasing numbers of 2 uF caps in parallel until the output climbed back to 240v, then bought a Motor Run Capacitor of that size off fleabay. All good as new for $7. (20 uF, 450 Vac)

  2. If I see correctly this is a bog-standard Honda GX160 engine clone. Should’ve looked on ebay for a GX160 piston, they are about $30, maybe even less in single quantities. Those small GX160 clone engines are cheap and fun, I need to practice my welding a bit more, earn some cash and I think I’ll make an RC toy car with one of them.

  3. That engine appears to be one of the Honda knock-offs – something like the GX240 series. Usually you can just order the equivalent Honda part and it drops right in. I still applaud this guy’s efforts as it majorly paid off. Interesting as it may sound, for years I attended of official Honda engine school and every year up through 2009 they would landblast the Honda engine copies, etc. There would be one disassembled on a table next to a real Honda engine and you could see the crankcases were thin and the quality was quite poor. At the last school I attended in 2009, the entire class was told that the engines being produced were of good quality and they could find nothing wrong with them. The advice was to sell Honda parts to whomever needed them. So whether the quality of Honda-copy engines was lacking or not, the official stance at least from 2009 was to sell OEM Honda parts to whomever asked for them – a financially advantageous move.

    1. Since Honda builds some motors in China as Jialing -Honda, is this all converging to a common source of parts and castings or are designs just sort of taking up Honda’s dimensions as standards to be built to, knowing that most of the engineering’s been well done and thus likely to be “good enough” when copied?

        1. There is a popular story of Yamaha setting up a motorcycle/scooter factory in China (20 years ago?) and shortly thereafter a Chinese factory opened across the street making Yamaha clones.

          1. The thing about stolen IP is that Chinese export subsidies are paid to factories that don’t sell in China, in order to protect the domestic Chinese companies from the same cheap crud they push abroad, so the products made for the western market are actually cheaper than the clones.

  4. Nice…. Good to see! What isn’t economical for the big store, is for the small guy with some knowledge and spunk. How much other stuff like this goes to the landfill? And how much do these “warranty returns” due to buyer ignorance (overfilling oil or abuse) cost other customers?

    1. How much stuff like this going to landfills? An incredible amount; now even big ticket items like huge flatscreens are not considered worth “repairing” even if that just means swapping out the motherboard or power supply module. And manufacturers are increasingly designing products that cannot be repaired. We are all doomed.

  5. Good job getting the generator working.
    on an aside, I can understand returning things if they were defective or you bought the wrong thing , and didn’t destroy it in discovering this fact, but please DON’T RETURN YOUR THINGS AFTER YOU HAVE USED AND ABUSED THEM. It may help someone as in this case, but in the long run it hurts everyone by driving up costs.

    1. A lot of generators are intentionally abused and returned when the buyer gets the first credit card statement after the hurricane. The big box stores have taken steps to stop this sort of fraud, but some things slip through.

      1. We were without power for 8 days here in Huntsville, AL after the big tornado outbreak we had (200+ tornados in a 24 hour period). Personally I feel we were all pretty lucky as the weather was perfect for being without power in the South, was in low 70’s all that week. Normally it’d be 85-95 that time of the year already. Could have been brutal.

        Day or two after the power came back on, went to Home Depot and saw a line of people all queueing up to return their generators. Really annoyed me. I could maybe turn a blind eye if they were struggling financially and needed the generator to power an iron lung for a loved one. But I don’t think that’s what was going on.

  6. The guy is a hoot. I was on the edge of my seat waiting for disaster and he managed to only have one big ‘oops’ moment, assembling past a part that required backtracking. The funniest was his wife’s gentle digs at him “My mom has a Dremel, too.” Way to take the manly clean off.

    1. It’s a good video series. Despite the occasional awkwardness, he knows what he’s doing (and so does she) and is showing how to do things on a back porch with limited tools. Videography and editing is good. The occasional ribbing at each other was pretty funny, and the final generator test made me say “Awwwww!”

  7. I recommend the youtube channel “Mustie1” — a guy out of New Hampshire who fixes small (and large) engines, generators, etc., that he finds on the side of the road. Puts up a new video every couple of days with his most recent fixes (most of the time — its just the carb).

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