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Discussion Starter #1
My 54" MMM seems to leave a row of partially cut grass right in the middle. I have sharpened the blades and the alignment seems good. I have noticed that the problem is worse in turns. I admit that I mow quickly but the problem is only a little better when I slow down. I was at 190 RPMs on the PTO this morning, and the grass was a little high. But it just appears that there is a coverage problem of some sort in the middle, where there is no overlap. The problem diminishes when I go over the same area again (cutting less grass). Solve this problem and you'll be the recipient of a coveted polite round of applause.
 

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Two things that can help. 1, make sure there is no buildup under the deck restricting grass and airflow. 2, run your mower at rated RPM. I run full tilt for optimal performance. Don’t worry, it won’t hurt your machine. And you aren’t saving anything including fuel by running it slower.
 

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Another thought, when was the last time you greased the spindles ..:dunno:

If after mowing at higher or recommended RPM , remove the deck and then slip belt off the pulleys and see if the middle blade turns as easy as the outer blades. :dunno:
 

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If the blades are old and been sharpened many times, they will leave a streak. Compare them to new ones to see if they are the same length.
 

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Discussion Starter #6
Thanks

Thanks for the replies, and I will look into those suggestions next time I have the MMM off. But just mowing again solved the problem in the short run. The grass grew in some places nearly a foot in two weeks (no idea why - hasn't happened before) and when I mowed over parts of it again the cut was perfect. It may be that the grass was just too high to get it all in one cut. For the moment I will just have to plan on mowing every week until things slow down.
 

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Thanks for the replies, and I will look into those suggestions next time I have the MMM off. But just mowing again solved the problem in the short run. The grass grew in some places nearly a foot in two weeks (no idea why - hasn't happened before) and when I mowed over parts of it again the cut was perfect. It may be that the grass was just too high to get it all in one cut. For the moment I will just have to plan on mowing every week until things slow down.
As others , raise the RPMs especially in tall grass. Yes I mow at 26-2800rpm for the engine , but if grass is high RPMs go to the 3200rpm makes a world of difference .
 

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Two things that can help. 1, make sure there is no buildup under the deck restricting grass and airflow. 2, run your mower at rated RPM. I run full tilt for optimal performance. Don’t worry, it won’t hurt your machine. And you aren’t saving anything including fuel by running it slower.
Same here - been doing that all my life.
 

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T also mow at full throttle. I want the fastest blade speed possible. I even considered changing the gear box pulley ( I have the 62C deck) to the one from a 54C deck to increase blade speed, but decided not to try and "out think" the JD engineers.
 

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If you were mowing very tall grass, there’s not many finishing mowers, including yours, that will perfectly cut it on the first pass. That is very normal to stripe and leave extra bits behind. Rough cut mowers will get it all in one pass but leave a “not-so-nice” finish. Two passes with a finishing mower will get it. You should also increase the frequency of how often you cut if it’s that high.
 

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If you were mowing very tall grass, there’s not many finishing mowers, including yours, that will perfectly cut it on the first pass. That is very normal to stripe and leave extra bits behind. Rough cut mowers will get it all in one pass but leave a “not-so-nice” finish. Two passes with a finishing mower will get it. You should also increase the frequency of how often you cut if it’s that high.

This

There's no way you are moving 6 plus inches of clippings through any finish mower without plugging the discharge. It was never meant to do this. Even "IF" you have dry sandy soil with thin grass, this is expecting too much.
 

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This

There's no way you are moving 6 plus inches of clippings through any finish mower without plugging the discharge. It was never meant to do this. Even "IF" you have dry sandy soil with thin grass, this is expecting too much.
Depends on the height you are cutting ar. If you cut at 4 inches, you should not have an issue. Now if you are trying to cut it like a golf green, well yeah, bigger problems.

Sent from my SM-N910V using Tapatalk
 

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Depends on the height you are cutting ar. If you cut at 4 inches, you should not have an issue. Now if you are trying to cut it like a golf green, well yeah, bigger problems.

Sent from my SM-N910V using Tapatalk
The OP said his grass grew over a foot in some places. Taking 12 inches of grass even down to 6 would be a lot for the deck to handle without issues let alone down to the customary 3 1/2 or 4. That's a lot of grass.
 

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Discussion Starter #14
Thanks to all

The grass was a foot high in many places. I don't know where it got the energy. But I did follow the advice on here and mow at about 3200 rpms the second day and that worked out better in the tall grass, but the second pass fixed the problem. In the past I have mowed at about 2700 rpms (thought I was saving fuel - you all will have to explain how it is that increased rpms don't use more fuel) but I'll stick with the higher number from now on. Does anyone tow a finishing mower behind them when they use the MMM?
 
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