Tach setup for HONDA GXH50

Discussion in '4-Stroke Engines' started by Kline's Kustoms, Jan 30, 2010.

  1. Does anyone know where to get a tach setup for a GXH50?

  2. MikeJ

    MikeJ Member

    Look for a company named SenDec. I purchased one of their less expensive digital tachs; nothing fancy. My tach monitors a 2-stroke engine. It has a self-contained lithium battery. When the battery goes dead in five years or so, buy a replacement unit. Read carefully the company's assumption that the magneto fires the spark plug on every cycle, not every other cycle as automobiles do.

  3. Thanks Mike. I want more of a mechanical type. If I can't find one I guess i'll have to go with the electronic type. Have you ever heard of anyone putting a mechanical type on a MB.
  4. MikeJ

    MikeJ Member

    I looked for a mechanical tach about six months ago. The only ones I could find were fairly big ones for for autos and motorcycles. The real downside is that they are dependent upon a strong 12 volt source to drive the needle across the face.

    The mechanical tach can be done for more cost. Also keep in mind that those mechanical tachs are calibrated to pick up a spark for every two cycles. Maybe a model or two can be calibrated for one spark per cycle. For my eight months being on this forum, I have not heard nor seen anyone with a mechanical tach. I know it can be done if you are willing to make some compromises.

    I wonder what the dirt track and motocross dirt bikes use?

  5. Old Bob

    Old Bob Member

    The Sendec can be used with two and four stroke engines, on the GXH50 with the magneto you will get an accurate reading using the two stroke setting.It doesn't care what the engine is, its counts revs when the ignition fires, the Honda mini four strokes fire every revolution (waste fire).
  6. MikeJ

    MikeJ Member

    Hey Kline -

    Here is a work-around to a true electro/mechanical tach..... If I needed this kind of tach badly enough, I would purchase a mechanical bicycle speedometer. They can be found in various stores for $20 or so. Probably another $10 for shipping if purchased from an Internet store. You have to hunt for them.

    Assume I have a 26 inch wheel bicycle. So I purchase a speedometer meant for 26-27 inch wheels. That tells me accuracy by the manufacturer is not great priority, but is good enough for me. The needle is moved based upon wheel RPM.

    I would develop a table, that when moving the wheel, a certain MPH needle deflection corresponds to a certain engine RPM. This assumes I have a fixed set of sprockets on the engine and on the back wheel. I would have to spend an evening with a calculator or spreadsheet to compute a "MPH translates to RPM" table. Then if I can remove the clear faceplate, I would apply labels to significant MPH/RPM points. Then replace the faceplate.

    The end result will be accurate to within a few percent of true. In the end, you have a speedometer, odometer, and a tachometer (when propelled by the engine).

    Just my thought for the day. I hope this leads to better ideas by someone else.

  7. HoughMade

    HoughMade Guest

    That was exactly my thought. I made a custom speedometer face and it would not take much for me to make a new one that includes RPM. If a person has fixed gears this is easy. Even with 2, 3 or 4 gears, this could be done. I have seen tractor tachs that include road speed for many different gears on them like below- just need to know what gear you are in and look at the applicable arc. You would not need to have a needle like that shown that spans the circle, just put the accessory arcs under the MPH arc.

    Attached Files:

  8. MikeJ

    MikeJ Member

    Hi HoughMade -

    I grew up on a farm, also, just west of Jasper IN. Your meter probably was installed in multiple models of John Deere tractors. I drove occasionally the farm's 720 2-cylinder Diesel. Like your meter says, RPM maxed out at 1500, road speed maxed at 15 mph (a danger to drive on two-lane highways, and rapid shifting through the gears was impossible with that hand-operated clutch (which I regarded as the enemy on that machine).

    For giggles and grins, I may try setting up a mechanical speedometer with RPMs on my next build. That way, history is not lost as when a battery goes dead.

  9. Old Bob

    Old Bob Member

    Harley Davidson used that same set up on their motorcycles.
  10. Erich_870

    Erich_870 New Member