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Voltage problems 48 inch scag walk behind

Discussion in 'Mechanic and Repair' started by scagmaster, Oct 28, 2007.

  1. scagmaster

    scagmaster LawnSite Member
    Messages: 8

    How do I find the 3350 rpm? What is the rpms at full throttle?
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    There is no telling what the RPM's are set to at full throttle unless you have one of these;


    Should be between 3600/3700 RPM.

    I have the first one on top in my tool box for setting/checking engines.
  3. Bill Kapaun

    Bill Kapaun LawnSite Senior Member
    Messages: 949

    If your engine is running properly, your full speed RPM should be up in that range, so your readings should be extremely close to what is specified. Look for readings that are noticeably "out of whack" for a quick test.
  4. johnp900

    johnp900 LawnSite Member
    Messages: 71

    Have you check the ohm's on the clutch? This mower was sold 04/19/2001 & probably about time for a clutch to go.
  5. outdoorpower

    outdoorpower LawnSite Member
    Messages: 6

    The clutch has nothing to do with voltage variance from idle to top speed if the voltage is being checked with clutch disengaged. If you have replaced the parts you say you have, you've probably either lost a magnet on the flywheel due to dirt and debree getting between the flywheel and stator or lost magnetism in the magnets
  6. johnp900

    johnp900 LawnSite Member
    Messages: 71

    Actually, the clutch has a lot to do with it. This mower does not have a battery. The clutch "tells" the regulator how many amps it needs. If the clutch is shorted or the gap is too wide, the electrical load on the clutch will exceed the amount the rectifier can provide. Also, in the main connector from the engine deck to the handle assembly, the main red wire can become burned & corroded due to excessive electrical load & exposure to the elements. This connection needs to be checked & repaired if needed. In reading the posts, this guy has just been replacing parts. To troubleshoot the system correctly, he NEEDS to check the clutch ohm's & air gap & check the wire harness connector. it should take all of 3 minutes to do this. If these tests prove negative, then go back to the stator & regulator. I will bet the problem is in the the area I described.
  7. scagmaster

    scagmaster LawnSite Member
    Messages: 8

    Guys, thanks for all the advise. I am going to spend the entire day tomorrow working on the mower. I am going to recheck the entire system. To answer the question about the clutch its an Ogura clutch it read 3.0 ohms and the gap is set to 10 to 12 thousandths per the scag dealer. The wiring harness is broke at the connector going to the handle so I put new ends on it. This looks go no burnt wires. Plus also I have remove all the swithes out of the circuit still the same result. I also clean the ground terminal.
    Thank you guys so much for your help. Keep the ideas coming GREAT SITE
  8. Bill Kapaun

    Bill Kapaun LawnSite Senior Member
    Messages: 949

    If you could place an ammeter in series with the electric clutch, you could observe current draw of the clutch through the entire speed range.
    Maybe something in the internal electrical circuit of the clutch itself is loose and shorting when the speed/vibration reaches a certain point?

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