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JD D160
Briggs 44S977-0026G1

Customer complains that she's having to go over most of her yard twice. I got it here to the shop and started mowing and she's right. After mowing a few stretches, and it looks almost like when you mow in reverse.
So I sharpened the blades, leveled the deck, and it's better, but still not cutting like it's got freshly sharp blades on it.

Belt is good. Pulley's are good. PTO seems to be engaging fine. Fast idle of the engine (briggs twin) is 3130 rpms on both sides. Engine sounds and runs fine. I didn't have any tall grass to see if it would bog down too easily, but what I cut was a couple of inches taller than the deck level. There was on place where a mower had been sitting for a few weeks that was pretty tall. Not real thick grass, and about 10" to 12" tall, I had to go over it twice too.

What blades are on it?

I've never found the tractor style units to cut well either. Not a purpose built mower. Trying to be a one stop shop for farmers. Pull a cart, cut some grass super machine.

Tires aired up proper? Use Oregon or OEM blades. After that, you are at the mercy of the deck design or lack of.

Hammermechanicman said:

What blades are on it?

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These kind. Not of sure the brand. I told the customer we could switch to the high lift brands come spring.


One thing I did notice, is that the grass chute lays very close to the ground. So that could reduce a lot of upward air flow. But I've never had a customer day the blade (above) did a poor job of cutting grass.

IS the deck open ?
Most gator style blades do not give a good cut if the deck has a mulch plug over the discharge chute
After that some blades just don't work with some decks
On the 42" EDGE decks we get down here, the Copperheads that Rotary supply are the only toothed blade that will cut properly
IFF it had the dedicated JD mulching deck then nothing will cut properly other than the JD mulching blades and if it is the timed deck with overlapping blades the blades are handed despite being identical, ( found that out the hard way ) .

Does it have a mulching plug or is it side discharge? Contrary to what most homeowners think gator type blades are not mulching blades. If side discharge you might try some high lift blades.

bertsmobile1 said:

IS the deck open ?
Most gator style blades do not give a good cut if the deck has a mulch plug over the discharge chute
After that some blades just don't work with some decks
On the 42" EDGE decks we get down here, the Copperheads that Rotary supply are the only toothed blade that will cut properly
IFF it had the dedicated JD mulching deck then nothing will cut properly other than the JD mulching blades and if it is the timed deck with overlapping blades the blades are handed despite being identical, ( found that out the hard way ) .

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The deck is open. But the chute hangs low to the ground. Like almost touching the grass that's just been mowed.

I would have to say those blades aren’t producing enough lift. RPMs are a little low. Is the deck leveled properly? Are there any holes sandblasted into the deck top? Installing GX21785 high lift blades will improve the cut. The GX21786 mulching blades will work also. I’m not sure if Rotary or Stens makes a high lift for the JD D160. Stens does make a direct replacement mulching blade. Rotary #11595 is 17” x 7 point star pattern hole.

MParr said:

I would have to say those blades aren’t producing enough lift. RPMs are a little low. Is the deck leveled properly? Are there any holes sandblasted into the deck top? Installing GX21785 high lift blades will improve the cut. The GX21786 mulching blades will work also. I’m not sure if Rotary or Stens makes a high lift for the JD D160. Stens does make a direct replacement mulching blade. Rotary #11595 is 17” x 7 point star pattern hole.

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That's the only thing I can figure too. Also, tomorrow, I may try raising the chute, just to see if I can get a little more air flow. She want to wait til spring for the high lift blades. She likes those gator blade for leaves.

PTmowerMech said:

That's the only thing I can figure too. Also, tomorrow, I may try raising the chute, just to see if I can get a little more air flow. She want to wait til spring for the high lift blades. She likes those gator blade for leaves.

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I can understand liking the Gator type blades for leaves. A deck leveling adjustment and raising the RPMs will help some.

Quality of cut is all about air flow. Gator blades don't create enough lift in certain grass types because the wing tips are serrated, which decreases air flow. The discharge chute is also choking the air flow. Put a new chute on it, OEM side discharge blades (or OEM mulch blades if running a mulch kit), set your high rpm at/about 3300, level the deck, and you should be good. I've seen this issue many times over the years, and this has 100% fixed everyone of them.

MParr said:

I can understand liking the Gator type blades for leaves. A deck leveling adjustment and raising the RPMs will help some.

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3100 RPM (fast idle) is too low for a Briggs V twin?

PTmowerMech said:

3100 RPM (fast idle) is too low for a Briggs V twin?

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Exactly. At 3600 they develop peak horsepower. Peak torque comes in around 3100. This is according to Briggs and Stratton. However, try 3300 RPMs and see how it cuts. You certainly don’t want to have your customer blow an engine straight out of your shop.
What @Will1988 said about the Gator type blades is true. The only time adequate lift is achieved with Gator type blades is when running the G6 commercial blades. The JohnDeere GX21786 mulching blades would perform better than the Gator type blades. Just add the JD composite chute blocker.
By all means fix the discharge chute.

If you are trying to bag or on leaf patrol, max revs is the ticket. Crank her up to 3600 and never look back.

something kept bugging me about the way the engine ran on PTO start up. It just sounded a little off. So while turning the idle screw in to get higher RPM's, I got to noticing the springs on the back side of the linkage bracket, At fast idle, the bottle spring (the smaller one) was loose, regardless of fast or slow idle. So I put the idle screw back to it's original position, and tweaked the governor bracket, to increase RPM's to 3350. The spring tightened up at fast idle.

So I mowed another round, and it seems that fixed the problem. I'm going to leave it at 3350, at least until spring when I put the high lift blades on it. 3600 scares me. LoL..

BTW, the deck chute, to get it up higher, will have to rigger nigged to get it up any higher. Maybe some sort of plate screwed onto the deck where the chute rests, to get it up some more. It's stock. So it's where it's supposed to be, minus what little wear there is.

Plasma cutter and a TIG welder. Good to go.

yes, DO NOT raise the rpms to 3600. I will debate anyone who recommends this! You will blow your engine. That rpm is too fast for the oil to provide adequate lubrication on the aluminum connecting rods against a steel crankshaft, not to mention cam lobes, pushrods, and valve spring abuse from over-revving. Ask me how I know! Something about zinc, but I digress. I'm glad you decided to keep it around 3350. Good luck. I hope that fixes it for you.

Will1988 said:

yes, DO NOT raise the rpms to 3600. I will debate anyone who recommends this! You will blow your engine. That rpm is too fast for the oil to provide adequate lubrication on the aluminum connecting rods against a steel crankshaft, not to mention cam lobes, pushrods, and valve spring abuse from over-revving. Ask me how I know! Something about zinc, but I digress. I'm glad you decided to keep it around 3350. Good luck. I hope that fixes it for you.

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According to this, the 875 series is to be ran at 3600 RPM's. But I'm not sure what series this Briggs 44S977-0026G1 is.

blades not upside down are they?

This link takes a little long to load. Look on page #23. Your particular engine is not listed. The reason for that is John Deere has a special model number for their Briggs supplied engines.

MParr said:

This link takes a little long to load. Look on page #23. Your particular engine is not listed. The reason for that is John Deere has a special model number for their Briggs supplied engines.

https://www.briggsandstratton.com/content/dam/briggsandstratton/na/en_us/Files/FAQs/2016_RepowerEngineSpecs.pdf

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From your link: "horsepower values are derived at 3600 RPM." As a matter of fact, it states that under all the twins and some singles. So maybe 3600 ain't as bad as it sounds.

Will1988 said:

yes, DO NOT raise the rpms to 3600. I will debate anyone who recommends this! You will blow your engine. That rpm is too fast for the oil to provide adequate lubrication on the aluminum connecting rods against a steel crankshaft, not to mention cam lobes, pushrods, and valve spring abuse from over-revving. Ask me how I know! Something about zinc, but I digress. I'm glad you decided to keep it around 3350. Good luck. I hope that fixes it for you.

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I agree that you should run an engine at the recommended RPM but back in the day of stock class WKA go cart racing we took the governor gear out if 5HP briggs engines and ran them for a full season at 6000 RPM with stock everthing except the oul dipper as the stock one would break. The one thing that wore was the valve guides. When i built engines i double stacked brass guides to help that. Piston, cylinder and rod wear was not an issue at 6000RPM. The local track ran a kiddie class with 3HP engines that had a plastic lobed cam. Ran those at 6000RPM too with no issue. The 5HP engine would blow the rod around 6500 and the 3HP would blow around 7000. I doubt 3600 will cause accelerated wear.

Scrubcadet10 said:

blades not upside down are they?

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They're right side up. But I may have them turned backwards. Sharp edge down. But on the other side. lol

I have no doubt that you will have the engine running as it should and the cut quality will improve, as a result.