Briggs Motor difficult to turn over

dawg1

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I have a 20yr old Briggs 281700 series 12hp motor on a Murray riding mower. Lately, it is hard to turn over. Sometimes when I turn the key, the starter doesn't engage at all. Other times, I have to rock the mower back and forth and then the starter will engage but barely rotate the flywheel. Sometimes it will engage and get stuck. I thought the battery was done (even though it reads 12+v on a multimeter -- bad amps??) so tried jumping it from the car. The starter definitely works better and cranks the motor but still appears to struggle to turn the flywheel 3-4 rotations (the rotations look slow) before finally spinning fast and firing up. So it appears the battery is weak but I thought I remember the starter working better than this. I replaced that starter 4-5 years ago but do they get weak? Anything else to try or check? Thanks.
 

ILENGINE

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what is your battery voltage while trying to crank. if below 12v then battery may be bad. also check voltage at starter while cranking if under 12v then problem is between battery and starter. if you have 12v then either starter is bad or bad ground.
 

jteuban

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Bent valve. Or check spacing on magneto that it is not rubbing. Could also be bad connection or solenoid. Does the compress. Feel normal when cranked by hand? Keep posting on here and I can prob help fix your prob.
 

dawg1

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By hand, the flywheel turns without much resistance and then hits a hard spot. I think I read that's normal somewhere else (?).
Next, I removed the spark plug and then the starter engaged each key turn and the flywheel spun faster. Is that expected or does that mean something? Thx
 

jteuban

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If it spins and then hits a spot it sounds to me like a valve that needs adjusted. A simple fix if you have the time. Check about this and get back to me on this. Check mag spacing and everything else before doing this post back and I can guide you through fixing valves.
 

dawg1

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The harder spot to turn I mentioned was turning it by hand. It goes around 1-2 times and then hits some resistance. I thought I read that was normal due to compression?
With the spark plug removed, the flywheel spins probably about normal speed.
Where is the magneto? What do I look at? Any link to a pic of what I'm looking at? Thx
 

jteuban

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Ok yeah that seems normal. The magneto is the thing that the spark plug wire is Att to you will have to take off the shroud to get to it. It is around the fly wheel held on by 2 screws at should not rub the fly wheel at all so if it is losen bolts and put it approximate a playing card thick away from the fly wheel and try again. Does the engine run at all or run poorly at Cretan times? Starter or batt connections? to be honest it could be a # of thing keep me posted after you try this and I will try to help you get to mowing great once again. Cheers
 

daddy3

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check the gap on the valves i bet the rocker arms are very loose and this will allow the intake and exhaust valve to stay closed just for a second longer than it should causing the hard start most people replace the starter or the battery first and this is most likely the cause
 

dawg1

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I don't think I have the Briggs motor where you can adjust the valves.
 

jteuban

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Might have to do a valve job on the intake valve. sounds like to me. No big deal but you have to take off the head. 45 min job most of the time/ with valve grinding compound and a new or perfectly good one from another mower will prob fix your issue.
If the mower is 20 yrs old it is not a OHV. just a flat head. Cheers.
 
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