MTD Yardwork mower kick back , is flywheel key damaged ?
- Thread starter naimc
- Start date
On a broken blade issue like this, probably have something internal went foul on you.
Old timers would actually WALK the yard prior to cutting. That way the old wise smart people would never have an issue like this.
slomo
Old timers would actually WALK the yard prior to cutting. That way the old wise smart people would never have an issue like this.
slomo
Its Me
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put a blade on it and a flywheel key, tighten the flywheel not tight I mean tight, you have enough in the key way for it to work, that would cost less than a new mower, like slomo said do a walk around, I remember that as a kid the old folks make you walk the yard first, that is when they called them Power Mowers,
i was working on a powermore 139cc and was fighting kickback on the recoil starter. I check the flywheel key it appears to be ok. When I got the mower it had way to much oil and thought it might be hydrolocked. I pulled the plug and removed what I could out of the combustion chamber and changed the oil to the proper level. I also made sure that the needle in the carb was also in good condition. I fought this issue on two other mowers where the seats were bad and I was flooding the system with gas and in turn made it hard to pull back the recoil starter
Update, the engine was sitting on in my garage for a few months, I finally opened it up and surprise ! I can't find anything wrong. Except I did now what to look for so I took out the cam gear without 1st looking of pins were still aligned.
Here are some pics of the inside :
I moved the gear before taking the pic so I have no way of know if it jumped, but I see no damage on the teeth so I have to assume it did not jump.
the crank cover was a pain to pull off, thank fully I purchase an 8inch puller this summer , again I don see anything wrong.
The plastic / metal cam gear nothing broken, compression release arm does not look damaged.
Compression release arn :
Rest of the gear box , here I can't remove gear you on the center shaft , in some youtube videos that gear moved back ward and it just retained by a pin, could this have shifted ?
I did not take the crank and piston apart because those look fine.
So where does that leave me ? here the things I can think of.
- When I adjusted the valves I was not on TDC cycle but other cycle where the piston is on top with valves not fully closed, which would mean the valve lash was made worse when I adjusted , which make sense as the kick back was strong after I touched the valves.
- the ignition timing is off, I found some video checking the timing by printing out on of these : https://www.blocklayer.com/degree-wheel.aspx.
- the shear pin for the fly wheel is really off , even though it look fine on the picture.
- Somethig else ?
I neglected to read all of the comments here, this one is golden " You need to try and start with the blade on the mower. Starting without the blade can cause the kickback." Wow that blows my mind, I never thought this would be possible but I'll take you work for it !
Its my brother that beat up the mower and broke the blade. I'm just interested in fix it. So I will reassembly and bet another blade attachment and blad.
thank you for the blade comment, oh boy live and learn all that tear down, probably just because I tried to run the mower without a blad !
there is even a youtub video about this :
Here are some pics of the inside :
I moved the gear before taking the pic so I have no way of know if it jumped, but I see no damage on the teeth so I have to assume it did not jump.
the crank cover was a pain to pull off, thank fully I purchase an 8inch puller this summer , again I don see anything wrong.
The plastic / metal cam gear nothing broken, compression release arm does not look damaged.
Compression release arn :
Rest of the gear box , here I can't remove gear you on the center shaft , in some youtube videos that gear moved back ward and it just retained by a pin, could this have shifted ?
I did not take the crank and piston apart because those look fine.
So where does that leave me ? here the things I can think of.
- When I adjusted the valves I was not on TDC cycle but other cycle where the piston is on top with valves not fully closed, which would mean the valve lash was made worse when I adjusted , which make sense as the kick back was strong after I touched the valves.
- the ignition timing is off, I found some video checking the timing by printing out on of these : https://www.blocklayer.com/degree-wheel.aspx.
- the shear pin for the fly wheel is really off , even though it look fine on the picture.
- Somethig else ?
I neglected to read all of the comments here, this one is golden " You need to try and start with the blade on the mower. Starting without the blade can cause the kickback." Wow that blows my mind, I never thought this would be possible but I'll take you work for it !
Its my brother that beat up the mower and broke the blade. I'm just interested in fix it. So I will reassembly and bet another blade attachment and blad.
thank you for the blade comment, oh boy live and learn all that tear down, probably just because I tried to run the mower without a blad !
there is even a youtub video about this :
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bertsmobile1
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There is not much in he way of a flywheel on mower engines and they need the extra momentum of the blade to continue to rotate.
A lot of push mowers will not start without the blades attached.
The engines that have a blade clutch usually have a heavier flywheel to compensate for the lost momentum of the blade.
A lot of push mowers will not start without the blades attached.
The engines that have a blade clutch usually have a heavier flywheel to compensate for the lost momentum of the blade.
Hammermechanicman
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Back in the 90's i built a lot of engines for charity racing. The Arthritus foundation ran Mini Grand Prix charity go cart races as a fund raiser. Sometimes they ran 3.5hp Briggs or other times 5hp Briggs. If you were running my "rule interpretation special" i replaced the cast iron flywheel with an aluminum one painted black. Made a big difference in how fast the cart could decelerate into a corner and acceleration out of a corner. The engines started and idled just fine. Other teams had no idea the the engines were running lightweight flywheels or modified cams or advanced timing or paper thin head gaskets. Yep, bone stock.....sort of.
I haven't seen a mower that wouldn't run without a blade.
I haven't seen a mower that wouldn't run without a blade.
bertsmobile1
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Seen a lot of them.
Just not enough momentum to over come vale spring ompression then engine compression.
Never a problem on blue smokes
Just not enough momentum to over come vale spring ompression then engine compression.
Never a problem on blue smokes
I "reassembled" the motor , ordered the original blade adapter with blade.
Mower started on 1st pull no signs of back kick on level pavement. Right after it started I heard a loud clang. stopped the mower flipped it over and found the blade adapter broke !
The motor is just on a temporary body. On the original Yardworks body the blade does not site as low to the ground.
Before starting I made sure the blade had clearance with the body. Although it was overhanging it looked like it had good clearance.
So now I am wondering why did the blade adapter break ?
- Because it's just a cheap clasting and I over torque it ?, ( I did not use a proper torque wrench so I have no idea how tight the bottom bolts was. This was just fitting test to see if the motor ran properly. I had no intention to cut grass. )
- The crank shaft bent ? I does not look bent when turning.
I guess the blade hit body in a way that's not clear.
So now my plan of action is purchase the same part again, but next time I will re-install everything in the original mower body .
Just wondering I should be aware of anything else ?
Mower started on 1st pull no signs of back kick on level pavement. Right after it started I heard a loud clang. stopped the mower flipped it over and found the blade adapter broke !
The motor is just on a temporary body. On the original Yardworks body the blade does not site as low to the ground.
Before starting I made sure the blade had clearance with the body. Although it was overhanging it looked like it had good clearance.
So now I am wondering why did the blade adapter break ?
- Because it's just a cheap clasting and I over torque it ?, ( I did not use a proper torque wrench so I have no idea how tight the bottom bolts was. This was just fitting test to see if the motor ran properly. I had no intention to cut grass. )
- The crank shaft bent ? I does not look bent when turning.
I guess the blade hit body in a way that's not clear.
So now my plan of action is purchase the same part again, but next time I will re-install everything in the original mower body .
Just wondering I should be aware of anything else ?
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