Riding mower lacks power when blades engaged


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Old 05-23-18, 07:38 PM
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Riding mower lacks power when blades engaged

bought a used motor for my big huskee made by MTD. Itís a 24hp Briggs intek v twin. It started fine the day I bought it. Iíve been 2 months installing it and modify pullies, etc. I cleaned the carburetor and installed new plugs, air filter, oil change. It starts and runs fine until you engage the blades and then it wonít now except on level ground. Iím hoping the governor is not messed up. Any thoughts?
 
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Old 05-23-18, 09:24 PM
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It sounds like to me it either has a bad blade spindle or it's only running on 1 cylinder. Have you checked to see if there is spark in both cylinders?
 
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Old 05-24-18, 06:05 AM
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I am assuming this is a new condition not related to the replaced motor. Go up the same slope with the blades disengaged. If it does, the governor isn't the problem unless you have adjusted it. If it doesn't. the governor travel is being limited or the mower deck is causing too much resistance. Could be blades or spindles or both.
 
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Old 05-24-18, 07:18 AM
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So many things that could be wrong.

You installed a used motor. Do you have any idea of the motor's condition? The motor may be in need of a overhaul or some other work. Just because it can get up to full rpm with no load doesn't mean it's capable of generating it's full rated horsepower.

As already mentioned. Have you checked the governor? Is it responding properly to load on the engine?

How about your install? Is the mower system creating undue drag? Are the spindles or pulleys getting hot? Any metal rubbing or scraping? Any belts dragging or rubbing?
 
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Old 05-24-18, 07:55 AM
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Is the engine the same as the one being replaced? A twin with two coils needs a diode in the kill wire. If you went from a one coil to a two coil engine, and used the same wiring harness you would likely have just one cylinder working.
 
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Old 05-24-18, 12:04 PM
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I appreciate all the information! It had a intek v twin 22 hp before. I just checked and thereís no spark on 1 cylinder?
 
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Old 05-24-18, 12:24 PM
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I believe I have it figured out. The wiring harness plugs didnt match. I just spliced them to the carb solenoid, charge wire and kill wire. I left the diode out. I
just watched a video that said it isolates the kill wire ground to each cylinder and is necessary. I will splice it back in and hopefully fix the issue, I will post back when I have time to work on it.
 
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Old 05-29-18, 03:11 PM
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Update, definitely issue with the wiring to the armatures. I took off the top of the motor to find that the engine has the diodes where the wires from each coil meet. I unplugged the right armature and I have spark. The mower runs and mows normal with this wire off. With one kill wire still attached to the other side, the engine will turn off if you drop the throttle to lowest setting before turning off the key. Since the diodes are in the wiring, I can't figure out how to wire it to work. Will it be ok to run it with that one wire off the right side coil?
 
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Old 05-30-18, 10:45 AM
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The small harness with the diodes in it is available to buy separately or you can make your own if you have some diodes (too bad radio shack isn't around anymore). You want current to be able to leave either coil but not enter.
 
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Old 05-30-18, 06:46 PM
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Which wire from the motor charges the battery. Do the wires from the armatures ( coil ) serve another purpose
except to kill the engine?
 
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Old 05-30-18, 07:11 PM
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The coils with the spark plug wires only serve the ignition, nothing else. The charging system for the battery is different.

The wiring harness you're working on with the diodes is the way you ground the ignition coils to kill the engine.
 
 

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