A Free DIYer Generator Head?



It may have happened when I was exchanging  emails with a Customer on Guam after the Island was hit by a large storm and people were without power for months.  I received several pictures of generators that died for all kinds of reasons and formed a mountain of metal at the local salvage yard on Guam. My customer of course is a DIYer and loaded several in the back of his mini truck to see what he could make run again.

What happened you say? An idea… it’s been floating around in my head for years now, and then Roger Sperle, and old duffer and friend from down the street started bringing home lawn mowers and parting them for salvage. The alum mower decks and engine cases add up and a pickup load makes a fair paycheck for a guy just trying to keep busy.

Roger stops by one day with three generators he got out of the junk pile behind the small engine repair shop over by Foss’ Grocery here on East Hill.  He wanted to know if I wanted to pick any parts off them before he busted them up into different piles of metal.  I thought for a moment….Dang! this may be the time to try that DIY idea? Is there a KISS way to convert those single bearing generators into more useful two bearing Generators?



If you look at the picture above, you’ll see what Allmand tells me is a morse taper, if you’ve looked at engines made for single bearing generators you’ll notice the shafts are different, they often have this same taper. Fact is, this shaft above is the crankshaft salvaged from the engine and cut off right up against the crank throw.  That long bolt runs thru the center of the generator shaft from the back and holds it all together. Once that taper takes a set, and the bolt is tightened, it’s mighty strong.














If you look at the picture above, you’ll see the end bell that normally bolts to the side of the four stroke engine, you might recognize that standard set of bolt circles.  Since I’m a poor machinist at best, I sent off this end bell and the shaft with a measurement or two to Randy Allmand and he whipped up a custom bearing carrier for this end.  The center of the bearing carrier indexes into the end bell center, the inner bolt circle was already threaded in the housing, so Randy created the carrier bolt circle to match the threaded holes to make the job easier for me.



After assembling the generator and tapping on the end bells, the shaft spins silky smooth, and there’s little left to do other than make a proper mounting plate.

Randy might be interested in making these conversion kits if there’s interest.. or… you can roll your own..

Thanks Randy!

George B.


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49 Responses to A Free DIYer Generator Head?

  1. Mikeotter says:

    I’ve often wondered about making a bearing plate for these…. I had no clue they are a Morse taper… I have one to go grab today 🙂
    Mike O

    • George B. says:

      I’m sure many of us have thought about this conversion. As I’ve learned, the only way to know what all is involved is to do it.

      A NOTE The EPA has unwittingly created a mountain of waste across the country. A large percentage of these generators found their way onto the pile because owners left an unstable and corrosive fuel in them, a brew that the EPA helped formulate. Some of these gen heads didn’t run a full hour. When owners get an estimate to fix the Generator, they find that the Carb is EPA compliant which means it can not be cleaned. Yes.. the all knowing all caring EPA didn’t want you adjusting that carb, or drilling out the jets to make it run better, so they made it so you couldn’t even clean it! The labor charge and the cost of a new carb normally discourages a repair. This normally means the old unit is tossed on the scrap pile and the small engine repair shop might make a new sale, or the customer is off to Home Depot or maybe Honda to buy another generator.

      Of course the small enging shop might have hired that 17 year old kid part time to pull off some of the parts in the way, so the carb could be replaced more ecomonically. But progressives think everyone deserves a ‘living wage’ and more. So our small engine shop owner doesn’t see any merit in hiring a kid… which means we as a society deny young people the op to gain hands on experience. The liberal mind has a very difficult time grasping the value of on the job training and what youth might learn, their minds are wired to see the child as a vicitim being abused by the Evil Capitialist Shop Owner who over charges for what should be a simple repair..

      One more note, Quinn F. went into a Southern California hardware store to buy some paint thinner, he found it, and as the retail clerk rang it up, a warning appeared. The clerk said “sorry, I can’t sell you this, it appears the county or possibly CARB just banned this stuff…. no kidding!

      More unintended consequences? Every DIYer should rush out and get a 55 gallon drum of this stuff and everything you need that might become illegal. fire fighters are gonna love this..

      • Barry Smith says:

        Thats pretty cool, lots of those things around. Two and a half years after hurricane Ike here in Houston, Craigs list is covered up with generators that have not been used since. Since we are forced to deal with ethanol here it’s tough to keep small engines going. Ethanol laced fuel must be treated with some kind of stabilizer or your just asking for problems. Wait till we get E-15. It is really going to be a problem in older small engines and outboard motors too. Just a note that will probably make you a law breaker. A dremel tool with a cut off disc on it is great for making slots in those carb adjustment screws that nothing fits.

        • George B. says:

          Barry, there are other carbs that have no adjustments and no way to get at the jets to clean them!

          E15 will likely destroy a flat head unless you can drill the mains, or enrichen the mixture..

  2. Is this still a single bearing generator or is it now a two bearing one?

  3. George B. says:

    The pictures above show the generator side ‘bell end’ being converted to a bearing support which converts it into a two bearing head capable of being belt driven. Single bearing heads generally make use of the engine’s crankshaft bearing for support on one side.

  4. Neil says:

    I am sorry but you people blaming ethanol for causing gunk in the carburetor are either misinformed or ignorant. Have you ever thought its the petroleum causing the issues not the alcohol. Not to mention all the additives they put in regular gas these days to actually make it work. I am sorry but when people start blaming the clean fuel for the problems it irritates me to no end. Hence the addiction to fossil fuel and foreign oil that gee we are fighting 3 wars over. And if anyone says its just to fight terror in the world is full of it.

    • George B. says:


      Don’t be sorry, but do understand what irritates many of us are people like you that pose a question rather than add any substance to the conversation. Help us understand why the manufacturers of power products including some snomobilies forbid the use of ethanol blends?

      Remember, we don’t need fight for oil, we have some of the most extensive reserves in the world within our own borders…the world might not be as you see it.. Posting your comment about fuel might give us some insight into how much thought you give something before you react to it. My guess is .. “leftie loosie, rightie tighty” would be lost on you..

      • Neil says:

        Well George, I am speaking from experience. Everything that I have ever owned did far better on E-10 than regular. Not too mention 2 identical engines that one burned regular and the other e-10. The E-10 engine had far less carbon build up on the plugs and ran smoother. I have never had any trouble with e-10 fuel and I use it in everything. My 1950 Farmall M, my 1974 dodge pickup, my 1969 Honda Motorcycle, my 1990 dodge, my 1993 ford ranger, my 2005 Kia, my 14.5 horse garden tractor, my chainsaw, my weed eater and my 5500 portable generator. So maybe your arrogance is unfounded. So you want something to the conversation, when you put anything in storage that runs on gas drain the tank, then varnish problems will cease. If not you will have to either clean or in CARB, carbs you will have to replace them. Blame the users not the fuel.

        • George B. says:

          Diesel Fuel properly stored can be used for 20 plus years. When the lights go out, we want it to work.

          This site is focused on off grid power, we prefer to store our fuel for extended periods of time as part of beign prepared. We all are forced to run these corrosive fuels in other vehicles, we all get by using them if we use the fuel before it goes bad. If you care to argue the fuel is stable, go right ahead, we choose to believe the findings of near countless small engine repair shops, and what the fuel dealers tell us.

          Vented fuel systems with daily temperature swings with humidity present can and do cause the ethanol to drop out of the fuel quickly. There are a lot of variables and just because you have not had trouble yet doesn’t mean it doesn’t happen, we normally figure running hours as part of our return on investment, the fact that something runs means less here. As for Arrogance, I think you own that.

          Fighting three wars for oil? Come on Neil, if it were about oil, wouldn’t we be drilling for our own?

    • jason says:

      Ethenol and Methanol will dissolve aluminum either in concentration or the amount of time it is left in direct contact – true the rest of your rant has validity

      • George B. says:

        Jason, you are right on, there’s a reason manufacturers of air cooled alum 2 stroke engines expressly forbid the use of eth and meth blended gasoline.. even more trouble is seen when fuel tanks open to the Atmoshpere are used..

    • Joe says:

      Ethanol laced fuel is destructive to engines, and in particular, the small engines on outdoor power equipment….in addition to the fact that it contains less energy per given quantity than pure gasoline. Ethanol attracts water, which corrodes aluminum, as well as more or less melting “rubber” parts such as crank seals and fuel lines. Actually, it creates more heat during combustion as well. In the case of two cycle engines, the ethanol inhibits proper oil mixing with the fuel. In some cases it causes separation of the fuel and destroys the engine as a result.

      If all of the above wasn’t enough to condemn ethanol, then the fact that it does absolutely nothing useful should. It does create more subsidies for farmers and more taxes for consumers. Oh, I almost forgot, it’s also successfully contributed to increased food and fuel prices as well. It takes more than a gallon of fossil fuel to create a gallon of ethanol with the most efficient methods, and in the U.S., we do it with the least efficient method(ethanol from corn). This ridiculous ethanol delusion needs to come to an end.

      • George B. says:

        Right on the money Joe….

      • George B. says:

        I couldn’t help but add on…. there’s a lot of people that just don’t get it! It was yesterday My wife filled the lawn mower, I heard it die, I pulled the hose between tank and carb, and water dripped out! well, you know the story Joe, I pulled the float bowl, pulled the tank, and thank goodness the filter stopped most of the water. My wife is extra careful, but I think the plastic gas can doesn’t seal perfectly, and the daily thermal cycle allowed air wiht humidity in. As we know, the marriage between alcohol and gasoline is ok unless moisture comes along, and then alcohol will divorce the gasoline and take up with the moisture and drop out of the mixture! This was likely what happened to my wife, as she told me she just had enough in the can to do the side yard…

        tree hugger niel should see the mountain of ruined mowers and small engines behind nearly every place that works on them… what kind of emissions are made to replace all the crap that is destroyed by ethanol?

    • Shane says:

      Agreed on all points

    • Jerry wood says:

      neil..alcohol is water based..think about that..really think about that before replying..if you were to add up all of the pieces of equipment that it has destroyed and could calculate the co2 emissions caused by this factor just in manufacturing a new device to replace the failed unit your jaw would drop..ethanol is not a viable resource at this time due to the fact that the infrastructure surrounding it is not compatible with it..until an internal combustion engine is engeneered to run on it efficiently then it is going to contribute to what you seem to be dead set against..you can argue this topic any kind of way you want to and will not prove me wrong

  5. Neil says:

    I have never said that gasoline was stable at any grade. If you store gas for longer than 3 months you are asking for trouble that’s the way it is. There is no way around it. Diesel yes I agree it is far better for storage it lasts for almost ever, unfortunately I have nothing that is diesel. That is yet why I say you have to drain it if its gas powered and your going to store it. As for cleaning out a gunked carb from varnished gas I have used Sea Foam to soak the carb in. As far as a CARB carb I don’t know, our state does not require that classification. As for arrogance whatever, maybe “what goes up must come down” is lost to you. As for drilling our own oil, no why would we. Ever heard of the Trans-Canadian pipe line they are pushing so hard for, we can get it other places according to greed. So I believe what I believe and you believe what you believe and lets leave it at that.

    • George B. says:

      Neil, Gasoline lasted for years prior to blending in ethanol.. there are people that drive over 80 miles to buy mo-gas, ‘the old stuff’.. not all of them are stupid. There are a few petrol engineers who have valuable antique motorcycles, …. they will not put ethanol blends in them. There are a number of well founded issues..

      While you’re out in the dark garage with a match looking for some ethanol blended gasoline in the bottom of a can…. we’ll push the button and be running with diesel.. gasoline was a far more reliable fuel before ethanol.

  6. james says:

    I don’t know why neil chose to post
    his rant on a thread about generator head conversion, but he should know there’s no sales in gasoline standby generators for obvious reasons. It’s either diesel, propane, or natural gas.

  7. Neil says:

    Well it depends on the size of the generator. That head would have most likely came off of a gas burner.I am posting my rant here just in answer to an earlier post.

  8. james says:

    a standy generator is not standing by if you need to find fresh fuel to put in it.

    • Shane says:

      You could drain the tank/carb and keep the gasoline in a different container. It does lose it’s more volatile compounds though, but that shouldn’t bother a generator.

  9. Neil says:

    Enjoy your oil!

  10. Quinn says:

    George, I like your idea. Waste not, want not.

    • George B. says:

      Thanks Quinn,

      This type of conversion is right down the DIYer’s Alley.
      We don’t need to make that front bearing support so fancy, all it need do it center properly and support the bearing. BTW, thanks for posting on topic.

  11. Homealone777 says:

    Well; I don’t know exactly what to say to that set of post’s by Neil. Lord Willing, I’ve seen how Ethanol blended fuels separate first hand by putting some in a mason jar, 3/4
    full and let it set and watch what happens over time with a sealed lid. I shook it up and let it stand. It turned a light milkey color, then; After about 2 weeks, sure enough. Water started forming in the bottom. Try it and see. I’m on you’re side George. For years straight gasoline was the way to go. Not anymore! I’m trying to go diesel all the way as hard as I can! BTW; Excellent idea on turning that single bearing into a self standing generator head. I’d like to try that myself.

  12. Brad Helms says:

    George, I’ve been doing this type conversion for years on 3 to 5k heads and running them off of Kubota water cooled tractor engines. I use used D600 3cyl and D722 3cly kubotas because they’re fairly cheap and run forever. B.T.W, these are very usefull as truck APU setups. All you need to add is a rooftop air or portable AC unit inside the truck. Most of these heads can be wired to deliver full wattage on one 120 line like an ST head…

    • George B. says:

      Hi Brad,
      Glad to hear you have been taking advantage of this conversion. Allmand says this one looked to have a standard Morse taper.
      If that is the case, there should be a shaft available somewhere with a morse taper and maybe even a key way? I have already revised my next conversion about three generations from this one. The next will be made of a more square piece of steel, the bottom will act as the feet and mounting for the front of the generator head.

      We all know that commodities spike, and eventually head back down. Buying anything with a ton of copper in it right now is not going to be cheap, this is a time for the DIYer to tinker. The wild card is the US Dollar, the Whores we elected just can’t seem to say no to spending, they buy votes by giving others money. This might mean that commodities might never again be as cheap for us.

      There are a number of small engines including 2 cylinder diesels that are surplused at times, most all the people I know who have fabbed their own gen sets are happy if they bought or found a decent gen head. As I mentioned, some of these mass produced gen heads look fairly decent in construction.. others look like throw aways. I still believe the key is a serp belt drive, lower the engine RPM, produce less KW, let the set live longer, and listen to less noise.

      As for the PMGs.. the price of magnets has gone from about four dollars for quality pieces to thirty dollars and climbing. If you have a pile of magnets on the rotor, and then you spend a fortune on the copper in the stator, you’ve got a lot of money invested…

  13. Brad Helms says:

    It’s NOT a morse taper.. The larger heads use an industry standard J609B. I’ve checked it against a morse and the angle is slightly different. The earlier ones I cut manually with the compound miter on my South Bend at about 6 degrees and then hand filed and sanded to fit the socket. The last one, ( This week ) I cut on my CNC lathe using Mach3 and their wizards at 3 degrees and it fit with very little hand work. This head is an industrial grade 3.5K that came off a Robin rental unit I bought at a scrap yard for $40, it has the largest taper I’ve seen yet, after cutting a few test pieces I ended up at the 3 degree setting. When I got it home, I emptied the water out of the cylinder head, poured a little gas down the spark plug hole and it fired on the second or third pull. The one drawback to this model ( RGX305D ) is it was designed to use an external exciter circuit from the engine which had failed. I plan to use the output from a 60 amp alternator to provide the current for this.

  14. Brad Helms says:

    Sorry George, I just re-read your post. If you contact Northern tool and tell them you need a replacement pulley shaft for the 5500 watt belt driven head ( item #165913-1106) you’ll get a shaft that has the J609B taper and fits a 7/8″ id pulley and uses a 3/16 key. I have no idea how much it’ll cost but it has to be cheaper than a custom made piece from a machine shop….

    • George B. says:

      I cut the crank off to make the first one.. Allmand turned the shaft down some to 1.125″ to allow us to use a very common and inexpensive bearing. I’d be interestign t know the price of this shaft if anyone checks, consider posting here. Until copper goes down in price, let’s DIY.

      Thanks again Brad!

  15. Brad Helms says:

    No problem. After doing a search on Gooooooooooogle I found the J609B dimension to be 2 1/4″ per foot taper. Allmand should be able to calculate the angle based on the starting diameter of the shaft blank. If you are using a shaft size that will be a press fit into the bearing, ( which you should ), he’ll have to cut the shoulder that fits up against the bearing at the right place to have the rotor properly located in the housing once everything is assembled.

  16. Paul says:

    Did anyone get a good number on the replacement shaft from Northern? I am in the same situation and need to fix a head from a 5 kw Briggs & Stratton head.

  17. Paul says:

    Is anyone making the end bearing plate for these? Anyone making a shaft? I have a shaft I could use from an old engine that threw a rod but it wouldn’t have a keyway.

  18. George B. says:

    I think the comments in this article gave places to look for the shaft..

    End bearing plate? If I had another made, it would be near square and the bottom would act as the mounting feet for the pulley end. No one is making them that I know of, Allmand would make them, but he needs a drawing, OR parts sent to him.

  19. Joseph S says:

    I am very interested in this Conversion Kit if Randy is making them. I may have others interested in them as well.

    Randy can contact me via email at joseph_sharp@yahoo.com. If you could give Randy my email I would greatly appreciate it.

    Thank you.


    Joseph S

    • George B. says:

      If you have a head, it might be good to read the entire thread and get the shaft you need to stick in that taper, as you read, Randy and I cut off part of the crank shaft to do this one..
      It’s best you build the fron legs into the front bearing support, I’d take your project to a local machinist, (a reitred one if you can find one) and let him advise you.

      Randy and I were just screwign around with this one attemptign to give DIYers and idea how they might put discards back to work.. As you read here, it’s not a new idea, and I woudl have been shocked if we didn;t get notice that other DIYers had done it! After all, we are a handy and thrift bunch.. Waste not want not, as Quinn said 🙂

      • Joseph S says:

        Thank you for the reply George.

        I just happen to know a retired machinist. 🙂 I do know that the shaft I need will have to fit a J609A cone.

        If anyone out there happens to have a shaft from a motor that fits this type of taper I’d be willing to purchase it.

        Thank you again. I truly love Utterpower.com


        Joseph S

        • George B. says:

          Joseph, please consider coming back and posting what you do.. my advice is you consider your mounts, and build them into the front adapter that will carry the bearing and the radial load, as you can see, I didn’t think that one through, so much easier to do it all with the front adapter!

  20. George B. says:

    I just re-read this thread 🙂 Brings a smile to my face.

  21. Joseph S says:

    I will definitely keep you posted.

    Thank you again.

    Joseph S

  22. Taylor says:

    I recently got a 5500 watt generator with a blown engine. I’d really like to have the crankshaft machined down and have a bearing carrier machined to support the other end of the generator head like you’ve done here. I’m only familiar with the v-belt pulleys and the shafts with a key way machined into it (like on lawn mower engines). Your output shaft doesn’t appear to have a key way. What is the diameter of your shaft? How is the pulley mounted to the shaft? Can you also tell me a good source for these pulleys (and belts). Thanks!

  23. Jim says:

    George, ever thought of just keeping the dead motor and driving that? In other words, remove piston and rod from dead motor, and attach a drive pulley to where the flywheel is located. You would be using the motor as a bearing drive shaft then.

  24. Captain Ron says:

    This is an old subject but I did one of these conversions in 1982. However, I cut the crankcase of the trashed engine and the shaft throw to leave enough to turn with the lathe and cut a keyway for the pulley. A section of angle aluminum welded to the bearing plate made a nice base.
    Last month I acquired a engine drive welder with a 9hp Robin. Had to open the engine to replace the governor shaft and noticed that this engine design is ready made for these types of conversions. The bearing carrier is a flat plate that would be easy to bolt or weld a base plate for feet.

    As for Neil, he’s a clueless tree hugger!!!

  25. Paul Kennedy says:

    Hi Guys,

    I know this is an older thread, apologies.

    Am I allowed to post links? I did a similar adaption some time ago however I didn’t get an adapter plate made I used a pillow block bearing like this


    I had the taper shaft made from BMS and case hardened as the engine one was a little short. A local engineer made the shaft in 15 minutes, I used 2 steel strips as legs mounted on the two mounting bolts on each side. The only power tools I have is a drill and a grinder so it’s all make do and mend

    I used a taper lock pulley on the shaft with 2 B profile belts on a smooth flywheel. 3 KW @ 1500 RMP works fine.

    Thanks for reading this


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