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Help with Riding Mower?

Discussion in 'Large Equipment' started by Larry Johnson, Jun 17, 2017 at 11:48 AM.

  1. Larry Johnson

    Larry Johnson ArboristSite Lurker

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    I appreciate all the help with my chainsaw, was wondering if y'all could help with a riding mower that I picked up real cheap. It's a Murray with a briggs and stratton motor 21hp V-twin motor (model 406677 0344 E1). The mower sat for a few years when I acquired it. The previous owner said he thought the starter was bad. New items that I added: battery (350 cca), starter solenoid, starter, main wiring harness. Standardard maintenance performed: oil change, old gas removed, carb cleaned, new filters.

    I have little mechanical knowledge, but I'm learning. Motor seems free with good compression. I don't have tools to measure. I've managed to get the new starter to slightly spin the motor, but then it starts clicking like a car does when the battery is weak and won't turn the starter. Could the rusty magnetoes(?) be the cause.

    Here's a short video of my attempt to start it.

    <p><a href="">With new 350cca battery</a> from <a href="https://vimeo.com/user57651465">Larry Johnson</a> on <a href="https://vimeo.com">Vimeo</a>.</p>

    After posting, I cleaned the rust off the magnetos and magnet on flywheel, and all around the flywheel. Gapped with a business card. Only slightly better and can't get a full revolution out of it unless I pull the plugs. With plugs removed it went around 4 or 5 times, then slowed and started clicking. Gonna charge the battery tomorrow. Don't know what to try next.
     
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  2. mijdirtyjeep

    mijdirtyjeep ArboristSite Operative

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    I would check the intake and exhaust rocket arm clearance. If they are a little loose, it will not allow the decompression bump when rolling over. Even a new battery and starter will come to a stop.

    I can't remember the specs, easy to find online though.

    Wait too long and it will bend a pushrod on the intake side I believe as it is aluminum. If that happens just grab an exhaust one as it is steel and stronger. They are both the same size.
     
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  3. Larry Johnson

    Larry Johnson ArboristSite Lurker

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    OK. Um, would that be the same as valve clearances (intake and exhaust).
     
  4. mijdirtyjeep

    mijdirtyjeep ArboristSite Operative

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    Yes, sorry about the wording.

    I should have put more thought into writing that response, seeing I already had a couple cold ones. :cheers:
     
  5. Larry Johnson

    Larry Johnson ArboristSite Lurker

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    No problem. I appreciate the reply. After doing some research last night, I spent and hour or so adjusting the valves this morning, but with no luck solving the problem. I believe I did it right, and made 4 or 5 attempts at it. Here's what I did; pulled plugs, turned engine until I saw the top (intake) valve close (down), continued turning with screw driver in plug hole so I could feel piston rise to top, then turning a little more until it went 1/4" down (according to two commetns I read referencing the B&S manual), loosened rocker arm, adjusted the gap down all the way, then backed off until I could get 0.005" gauge in with a little resistance, tightened rocker. Did the same for the bottom (exhaust) valve. Same procedure at the other side starting with turning engine until I could see top valve move and piston to tdc + 1/4" down. (Not a precise method.)

    I'm not sure what to try next. Any suggestions?
     
  6. Larry Johnson

    Larry Johnson ArboristSite Lurker

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    Update: the valve adjustment did the trick. My new battery just needs to be charged. That's why it wouldn't turn the motor after the valve adjustment. The motor turns great with jumpers attached. Thanks.
     
  7. mijdirtyjeep

    mijdirtyjeep ArboristSite Operative

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    Glad you got it going!!
     
  8. Larry Johnson

    Larry Johnson ArboristSite Lurker

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    Well, I don't actually have the mower running yet. Getting the engine to spin was a big first step.
     
  9. backhoelover

    backhoelover 2 cycle carb master, don't believe me just ask!!!!

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    another thing on them engines. if it is hard to start you need to adjust the throttle linkage so it will close the choke more. i have seen this problem on over a 100 briggs twins. had a couple customer tell me they was told they need a new engine. and one was charge for new carb and coils and they said the unit was getting tired. good luck also you can get am carb off ebay and i have had good luck with them. a rebuild kit for that carb is 80.00 new carb is 160.00. in briggs updates class they said to replace the carb and not worry with rebuild.
     
  10. Larry Johnson

    Larry Johnson ArboristSite Lurker

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    Thanks.
     
  11. Larry Johnson

    Larry Johnson ArboristSite Lurker

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    Got it fired up after disconnecting the kill wires to the two coils. Does that mean those wires need replacing back to the part housed in clear plastic, or does that mean a safety switch is bad. I checked all the switches with an ohm meter and all appeared in good order.

    [​IMG]Untitled
     
  12. backhoelover

    backhoelover 2 cycle carb master, don't believe me just ask!!!!

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    That harness has two diodes in it if one goes bad it will ground the other coil out
     
  13. backhoelover

    backhoelover 2 cycle carb master, don't believe me just ask!!!!

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    If both coils are not firing you either has a short to ground or a safety switch that is goinf bad. I had a scag come in one time that had a safety switch that was going out guys said it was the break switch I tested all the safety switches for hrs ended up being left control lever safety switch. I use a 12 test light since you are testing ground need to hook clip end to battery positive and start working the safety switches and see if U can't get the light to go off have to get the ohms meter out
     

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