Loss of power while mowing

[adsm08 2,059]

I recently got my 800 Special put back together with the deck and PTO and tried to mow for the first time. It started fine, but within minutes it was bogging down and trying to stall. Putting the clutch in and letting it catch up helped a bit, but eventually it was just unable to continue, even in first gear at full throttle.

 

8 HP Briggs against a large deck, not sure of the exact measurments. It's the smaller 3-blade side-discharge deck.

 

Any ideas? I know I should probably start by getting the carb into an ultra sonic cleaner for a night.

[cschannuth 3,816]

My low hour, like new 2000 314-8 is disappointing with a 42” deck so I can’t imagine an 8 horse trying to spin a decent size deck. Admittedly, I’m used to a 520 and a C-161 with a twin Briggs so  I’m spoiled for horse power. They both mow in high gear with a 48” deck with ease. 

[Kelsey 91]

1 hour ago, cschannuth said:

My low hour, like new 2000 314-8 is disappointing with a 42” deck so I can’t imagine an 8 horse trying to spin a decent size deck. Admittedly, I’m used to a 520 and a C-161 with a twin Briggs so  I’m spoiled for horse power. They both mow in high gear with a 48” deck with ease. 

 

* Kelsey kicks a can down the street while he stubbornly mutters to himself about this comment.*

[adsm08 2,059]

2 hours ago, cschannuth said:

My low hour, like new 2000 314-8 is disappointing with a 42” deck so I can’t imagine an 8 horse trying to spin a decent size deck. Admittedly, I’m used to a 520 and a C-161 with a twin Briggs so  I’m spoiled for horse power. They both mow in high gear with a 48” deck with ease. 

 

I know this deck is pushing it for the engine size, and I'm not expecting great performance. This is a backup mower or for use when I have to do it mid-week, to hopefully get it done a bit faster. This was trying to stall the engine in first gear. I have run 310-8s with the same or bigger decks with no issue. I can't believe that 2HP is going to make that kind of difference.

[tom2p 2,394]

If it starts quickly and runs relatively clean / smooth - not sure if carb clean will do much ?

 

maybe do a compression check ?

check the muffler ?

 

 

decades ago (when I had more hair and less stomach) ... sometime around mid 80's ... I was cutting grass with my 704 and it began to lose power ... sounded a tad different ....   was concerned the engine was just about done ... 

 

the muffler was bad - internals rusted and collapsed and basically choking the engine 

 

replaced the muffler and then good to go 

 

 

Edited July 29, 2021 by tom2p

[Ed Kennell 38,174]

2 hours ago, cschannuth said:

My low hour, like new 2000 314-8 is disappointing with a 42” deck

That really surprises me Craig.      I have run 42"SD on 312H, C-120H, and Raider10 and they have all done a great job.    Just my experience.    For the 48"ers I use the 417H

[OutdoorEnvy 1,522]

3 hours ago, cschannuth said:

My low hour, like new 2000 314-8 is disappointing with a 42” deck so I can’t imagine an 8 horse trying to spin a decent size deck. Admittedly, I’m used to a 520 and a C-161 with a twin Briggs so  I’m spoiled for horse power. They both mow in high gear with a 48” deck with ease. 

 

Yeah something must be up...My 312 runs a 42" SD great.  It has mowed really heavy stuff with ease...Are you sure it might not be the friction disc losing traction or something or the mule needs tightening? 

[cschannuth 3,816]

1 hour ago, Ed Kennell said:

That really surprises me Craig.      I have run 42"SD on 312H, C-120H, and Raider10 and they have all done a great job.    Just my experience.    For the 48"ers I use the 417H

It runs perfect and it’s quiet and smooth as can be. it’s just that I can’t get a clean cut in second gear high range like I can with my bigger machines. But, my yard is very thick because I’m kind of a nut when it comes to fertilization.

[cschannuth 3,816]

51 minutes ago, OutdoorEnvy said:

 

Yeah something must be up...My 312 runs a 42" SD great.  It has mowed really heavy stuff with ease...Are you sure it might not be the friction disc losing traction or something or the mule needs tightening? 

 

It runs perfect and it’s quiet and smooth as can be and only has a couple hundred hours on it.  it’s just that I can’t get a clean cut in second gear high range like I can with my bigger machines. But, my yard is very thick because I’m kind of a nut when it comes to fertilization.

Edited July 29, 2021 by cschannuth

[tom2p 2,394]

35 minutes ago, cschannuth said:

 

It runs perfect and it’s quiet and smooth as can be and only has a couple hundred hours on it.  it’s just that I can’t get a clean cut in second gear high range like I can with my bigger machines. But, my yard is very thick because I’m kind of a nut when it comes to fertilization.

your experience does not surprise me 

 

I have a great running 312-8 - but 416-H feels like it has twice the power    ... 520 obviously would feel even stronger 

Onan twins really excel at cutting heavy thick grass 

 

 

Edited July 29, 2021 by tom2p

[wfrpalm 218]

How about the governor?

 

 

[953 nut 55,229]

12 hours ago, adsm08 said:

I know I should probably start by getting the carb into an ultra sonic cleaner for a night.

Seems like a few people got 

I think you are on the right track. A set of pionts and condenser should also be considered.

   Are the bearings in the deck and muel drive all in good condition.

[cschannuth 3,816]

8 hours ago, tom2p said:

your experience does not surprise me 

My 314 is so smooth and quiet that I thought maybe it wasn’t reaching full rpm so I checked it and it was it just under 3600 RPM so it’s doing everything it should.  Because it’s so quiet I love using it and I’ve turned it into one of my toward tractor but don’t use it any more for mowing. Consequently the brand new looking 42” deck sits in my shop.

Edited July 29, 2021 by cschannuth

[Jeff-C175 7,202]

10 minutes ago, cschannuth said:

so smooth and quiet that I thought maybe it wasn’t reaching full rpm

 

After I rebuilt my deck and repaired the hole in my muffler, I thought the same thing!

[cschannuth 3,816]

1 minute ago, Jeff-C175 said:

 

After I rebuilt my deck and repaired the hole in my muffler, I thought the same thing!

My 2000 is by far my newest tractor so that probably has a lot to do with it also.

[adsm08 2,059]

11 hours ago, wfrpalm said:

How about the governor?

 

 

 

I do still need to check that. I think it works, as the throttle adjusts, but my cable is stuck. I have to loosen the cable clamp at the carb and move the whole thing. It also does not bog or try to die when loading the engine by taking off.

 

10 hours ago, 953 nut said:

Seems like a few people got 

I think you are on the right track. A set of pionts and condenser should also be considered.

   Are the bearings in the deck and muel drive all in good condition.

 

As far as I know all my bearings are OK. I don't have any play or roughness.

 

This is not an immediate thing when it is first loaded up, it is a gradual loss of power as the extra load is left in place. Almost like when mowing if you gradually get into a patch that is too thick, except my grass is not particularly thick right now.

 

[WheelHorse520H 708]

22 hours ago, tom2p said:

If it starts quickly and runs relatively clean / smooth - not sure if carb clean will do much ?

 

maybe do a compression check ?

check the muffler ?

 

 

decades ago (when I had more hair and less stomach) ... sometime around mid 80's ... I was cutting grass with my 704 and it began to lose power ... sounded a tad different ....   was concerned the engine was just about done ... 

 

the muffler was bad - internals rusted and collapsed and basically choking the engine 

 

replaced the muffler and then good to go 

 

 

That actually happened recently to my brother’s truck, a baffle in the catalytic converter lodged itself choking the engine. Every time the thing tries to shift (it’s an automatic btw) it lost power and never shifted, and when it did, it was lurching like crazy. Point is I think your onto something.

[adsm08 2,059]

38 minutes ago, WheelHorse520H said:

That actually happened recently to my brother’s truck, a baffle in the catalytic converter lodged itself choking the engine. Every time the thing tries to shift (it’s an automatic btw) it lost power and never shifted, and when it did, it was lurching like crazy. Point is I think your onto something.

 

Cats don't have baffles. They are filled with a square or honeycomb clay matrix impregnated with various precious metals to perform the chemical reactions of breaking CO, HC, and NOx into CO2 and H2O. No baffles.

 

However a partial exhaust restriction could account for my symptoms.

Edited July 30, 2021 by adsm08

[WheelHorse520H 708]

8 hours ago, adsm08 said:

 

Cats don't have baffles. They are filled with a square or honeycomb clay matrix impregnated with various precious metals to perform the chemical reactions of breaking CO, HC, and NOx into CO2 and H2O. No baffles.

Not the point. There was a long “telephone line” before I heard about it. Against the point is something could pop loose and lodge itself to choke the engine.

[Jeff-C175 7,202]

2 hours ago, WheelHorse520H said:

something could pop loose

 

I think they've pretty much solved the problem of the honeycombs crumbling but I had exactly that happen on two different cars.   VERY early ones though, when catcons first started being used. 

 

[lynnmor 7,306]

A vacuum gauge can help diagnose a restricted exhaust.  Attach the gauge between the carburetor and the engine, if you can find or make a place, and then check readings at idle and various speeds up to full throttle.  If the vacuum drops considerably at higher speeds, then that would point to a restriction.

[adsm08 2,059]

3 hours ago, Jeff-C175 said:

 

I think they've pretty much solved the problem of the honeycombs crumbling but I had exactly that happen on two different cars.   VERY early ones though, when catcons first started being used. 

 

 

It still happens.

 

Ford had an issue with the Rangers around 2011 the LH cats would just come apart. We'd get our sun screen and swim short on before we started removing one so that we'd be all ready for the beach when it arrived.

[WheelHorse520H 708]

4 hours ago, Jeff-C175 said:

 

I think they've pretty much solved the problem of the honeycombs crumbling but I had exactly that happen on two different cars.   VERY early ones though, when catcons first started being used. 

 

This happened on a 1999 Chevy 

[kpinnc 12,053]

I would check the deck height when setting down on the guage wheels. The front of the deck should ride just slightly lower than the rear. This sets the blade "discs" lower in the front so the engine isn't fighting resistance at the back side of the blade travel. If they are set just 1/4 inch lower in the front, the deck load on the engine is way less. If the rear is even with or lower than the front, the blades have to cut the full rotation, and that is alot of parasitic drag.

 

The adjuster link pictured above is how to adjust how the deck rides when down on the wheels. It doesn't take much turning to make big changes.

Edited July 31, 2021 by kpinnc