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Building an electric start for a pull-start gas engine

Discussion in 'The Tool Shed' started by dremu, Feb 10, 2008.

  1. dremu

    dremu Officious Thread Derailer Premium Member

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    Yeah, I know, I'm nuts... but we knew this.

    And I donno that this belongs in the tool shed, but the Lounge is so full of Fumes and his wawas that I'm scurred.

    Soo ... if I am tired of pull-starting my gas engine, how to go about making an electric start? I have a 12V battery as part of the project, so a tiiiny little starter, like maybe for a Japanese 4cyl motor? Or maybe an electromagnetic clutch, like on an air conditioning compressor, and a smallish electric motor?

    On generators and such that have electric start, is the starter an integral part of the engine, or is it a separate unit I could scrounge and use?

    -- A
     
  2. dremu

    dremu Officious Thread Derailer Premium Member

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    Well, got bored and took the recoil start mechanism off. There's already a clutch mechanism on there, so that it drives the motor when you yank it but then disconnects once the motor kicks in. The only weird thing is that it's an almost-square drive. The recoil starter fits on it with an eight-point sort of socket.

    Conveniently, however, a 12-point 7/8" socket seems to fit, and my trusty Dewalt cordless drill starts the thing up nicely in high gear... so now I just gotta find an el-cheapo cordless drill that'll do ~1200-1400RPM. All the Harbor Freight-type cheapos seem to only do the low-gear ~500RPM. ::sigh:: Such is the life of a nerd =))

    -- A
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Why not contiue using the DeWalt? Or are you looking to create a redneck cordless starter from something cheap?

    Rene
     
  4. Drey

    Drey 3/4 ton status Premium Member

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    Older Kohlers had a electric start system, might try looking at them.
     
  5. dremu

    dremu Officious Thread Derailer Premium Member

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    Largely the latter -- the intent being to build something onto the engine that is semi-permanent. (The engine in question runs a York as a gas-powered air compressor, and I'm starting to hate the recoil starter and like the idea of pushing a button. Yes, I *could* get the carb rebuilt so it starts easier, or I *could* even get a "real" electric-start engine, but this is more fun. Or, as you say, redneck.)

    -- A
     
  6. DEMON44

    DEMON44 Low-Tech Redneck Premium Member

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    At my old shop we used 2 Honda motors that were electric key start and pull start. one was 9hp the other newer one was 11hp. They were coupled to small hydraulic pumps as portable hydraulic power units. So you're not way off base, they exist. The 9hp was pretty old too. uses a little tiny 12v starter motor, nothing fancy, very straight forward
     
  7. 3 on the tree

    3 on the tree 1/2 ton status

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    The larger Tecumseh engines have elec starter held to the side of the engine with 2 small screws. They are 110V. Push button mounts on top.

    Put a pulley on the elec starter, and an AC clutch pulley on the engine, with a voltage reducer. Connect with a V belt. When you hit the pushbutton, it energizes the clutch, and the starter spins the motor. When you let off the button, the clutch disengages.:D
     
  8. dremu

    dremu Officious Thread Derailer Premium Member

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    Hmmm. I happen to have a spare York clutch and pulley sitting there, too. If my cordless drill idea doesn't pan out, I'll scrounge a little Japanese starter motor and go this route :thinking:

    -- A
     
  9. Fordum

    Fordum 3/4 ton status Premium Member

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    What make and model of engine? There are about 3 ways to go. The best, is to use a factory starter. Look at the flywheel while you have the cover off, and see if there is a set of teeth along the edge. I put a 12 volt electric start on my trash pump Briggs. They made that motor with electric start, but used the manual version on the pump. I just ordered the starter and bolted it on. Later I looked at the shop manual and realized that the electric start version had a coil under the flywheel and a little regulator. Ordered them, and had a charger that would keep the battery charged.
    Or, there are companies that sell a kit that let you use an electric drill to start it. I have used them but never installed one. A friend had one on his lawnmower. Somehow you drilled a hole in the center of the cover if I remember right, and there was a socket that was in the hole. You put a drive shaft in the drill, put it in the socket and cranked away. The nice part was, the pull start stayed on. I found a picture of one, it jogs my memory and I think this was how it worked.
    Problem is, its not available from here.
    http://www.amazon.com/System-Lawn-Boy-Tecumseh-vertical-engines/dp/B0002H33YG
    Its called Spin Start. If you can't find one, maybe this will give you enough info to build one.
    The third way, is what I use when I am troubleshooting a Briggs engine that won't start. I found a socket that will fit over that almost square shaft. 12 point one I believe. Then just take the cover off and use an extension that I cut the female part off so it would chuck up in my 1/2 drill. I also ground some flats on it, since the chrome did not want to let the chuck get a bite.

    j
     
  10. dremu

    dremu Officious Thread Derailer Premium Member

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    Holy dead thread reanimation, Batman! :haha:

    Yep, a 12-pt socket does indeed fit onto the shaft, 7/8" IIRC, and I remember what you mean about almost-square.

    And this particular flywheel wasn't toothed, so I didn't have any option there.

    I messed with cordless drills, but eventually got an electric starter and have it rigged with a pulley for torquer multiplication. (I'd call it "gear reduction", but there's no gears :haha: ... just a small pulley on the starter and a larger diameter one on the crankshaft.) I got it all wired up and it works pretty well, the little Honda alternator charges the auxiliary battery easily enough, and the motor can run both it and the York *just barely* at WFO ... and then other projects came along and I haven't gotten around to finishing plumbing the York, etc. So many projects, so little time =))

    All good info, though, and thanks!

    -- A
     

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