Mower leaves clumps

Joined
Apr 17, 2012
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3,346
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West Michigan
So I have a Lawnboy walk behind with the smart drive speed thingy (pushbar controls drive speed). Past few seasons it has been leaving progressively worse grass clumps behind as well as missing patches of grass while mowing. These missed pieces tend to be approximately centerline with the mower deck. I tried sharpening the blade without improvement so I replaced it- no improvement. Definitely gets worse in between cleaning the deck of built up clippings but also is present with a freshly cleaned deck. This is making me want to upgrade to a nice, new Husqvarna but not really in the plan for this year. Any suggestions to combat this issue (other than even more frequent mowings)? I do typically cut with the mulching plug in but if I miss a cut I have to open the side cute otherwise it bogs out pretty easily.
 

buck91

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Apr 17, 2012
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West Michigan
Originally Posted by Brian123
Are you mowing when the grass is completely dry?
Ideally. And that definitely decreases the problem but it still misses tufts down the center line. Unfortunately, especially early in the season there are a few sections which stay rather damp 24/7.
 
Joined
Dec 29, 2011
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South Dakota
Clumps are the result of the blade not chopping up the grass properly. To reduce clumping slow down, sharpen the blade, and clean the deck. If none of the above work try a different blade? The cheapie mulching blades at Runnings and Tractor Supply are actually pretty good.
 
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Aug 22, 2019
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AR
Check the leveling of the deck.....needs to be a certain way - in manual. - and of course - sharp blades.
 
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Feb 19, 2007
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Maryland
After you level your deck, try installing a set of Oregon Gator G5 Mulching Blades. They are fabulous! I could not believe the difference between using the lawn tractor manufacturer's mulching blades and the Gator G5 blades. Day and night difference and reduced my clumping issues by 90%. I even put Gator blades on my Toro mulching push mower. https://www.oregonproducts.com/en/p...tor-mulching-blades/c/g6-mulchingblade-p I recommended them to a couple of friends with large lawns who also use mulching blades and they love them as well.
 
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Originally Posted by tundraotto
Check the leveling of the deck.....needs to be a certain way - in manual. - and of course - sharp blades.
Try mowing with the front wheels one notch lower than the back. You should only be cutting off about 1/3 of the grass blade length, i.e., cut 5 inch grass down to about 3 to 3.5 inches, the proper length for our Michigan grasses.
 
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Yes, if everything else is in order, make 100% sure the blade is on correctly. You wouldn't be the first person to install it backwards so no shame in verifying.
 
Joined
Dec 30, 2019
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Latham, New York
OK, it sounds like you are mulching from the OP. So I would conclude the lawn boy is getting over whelmed (for whatever reasons). Is the engine bogging when the clumping happens? A mower upgrade with a bigger engine might be the solution.
 
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Jan 22, 2011
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Sounds like the engine needs a "tweek" to get the RPM up just a little. Also, the decks need to be clear of all dried grass to work well.
 
Joined
Mar 8, 2012
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MO
If you are trying to mulch 3 or more inches of spring growth at a time and moving pretty quickly that is going to overwhelm the deck capacity. You need to cut more often and also possibly at a slower pace to give the blades time to mulch. Are you scalping 6 inches of grass down to 2"? If so, no mower will be able to do that and mulch without clumps or missed spots.
 
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Jun 28, 2003
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Illinois
Originally Posted by chemman
After you level your deck, try installing a set of Oregon Gator G5 Mulching Blades. They are fabulous! I could not believe the difference between using the lawn tractor manufacturer's mulching blades and the Gator G5 blades. Day and night difference and reduced my clumping issues by 90%. I even put Gator blades on my Toro mulching push mower. https://www.oregonproducts.com/en/p...tor-mulching-blades/c/g6-mulchingblade-p I recommended them to a couple of friends with large lawns who also use mulching blades and they love them as well.
I use these on my John Deer F510 38" front mow. I have two sets and all I do is mulching. They hold their sharpness too. At one time I also had some short 9" lawn edger blades attached 90 degrees to the main blade.
 
Joined
Sep 10, 2008
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Cold Lake, Alberta, Canada
If the mower has an automatically controlled throttle the spring could be losing tension and causing it to run at lower RPMs which could cause clumping. I partially solved this issue on my cheap push-mower by stretching the spring a bit to raise the RPM. It helped with bogging down in thicker grass as well.
 
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Jun 28, 2003
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Illinois
Originally Posted by Surestick
If the mower has an automatically controlled throttle the spring could be losing tension and causing it to run at lower RPMs which could cause clumping. I partially solved this issue on my cheap push-mower by stretching the spring a bit to raise the RPM. It helped with bogging down in thicker grass as well.
John Deere uses some goofy sized belt that the thickness is between 1/2" and 5/8". So I use a 5/8" on the 1:1 PTO to deck and a 1/2" for the deck. The thinner belt sits deeper on the deck drive pulley and spins the blades faster. A lot cheaper too!
 
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I have a lawnboy mower that has always done the same thing. Cuts okay, just doesn't cut chop the grass like it should. I don't understand what people see in these mowers.
 
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