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Bush Hog Hd-12 Hydro Or Engine Doesn't Seem Right

bush hog hd-12 hydro transmission

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#31 NUTNDUN OFFLINE  

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Posted April 16, 2013 - 08:17 PM

Not sure what engine you have but it has points and I found 3 different ways to set the timing in a manual

1 - point gap

2 - test light, more accurate, static.

3 - timing light, lining up the marks dynamically.

 

It also appears that the points are camshaft driven, it the cam/crank is off 1 tooth the engine would probably run but would not run right and the ignition timing would be off for sure.

 

???

 

I think the motor is not making the power it should from what I see in the video.

 

 

I triple checked myself when I lined up the crank and cam gears. 

 

The only thing i did in regards to the timing was adjusted the points. I can see about using my meter to check it better.



#32 DH1 OFFLINE  

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Posted April 16, 2013 - 08:20 PM

Says to line up the marks on the flywheel the points should be at make/ break point.

 

http://gardentractor...12d-tra-10d12d/


Edited by DH1, April 16, 2013 - 08:21 PM.

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#33 DH1 OFFLINE  

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Posted April 16, 2013 - 08:34 PM

Looking at the video when you open up the throttle with no load the motor responds good but under load it doesn't have enough power, just like you say.


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#34 NUTNDUN OFFLINE  

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Posted April 16, 2013 - 08:36 PM

I am kind of thinking that even though it is an older 12hp cast iron engine. The HD-12 is a large garden tractor and also pretty darn heavy. Considering the tires are loaded and I have the Cub weights on there. When I got everything setup for the video, at first I figured I could just stand beside it and move the hydro lever but when doing that it easily spun the tires and wouldn't bog. Once my fat arse climbed on it then it would bog down.



#35 olcowhand OFFLINE  

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Posted April 16, 2013 - 08:45 PM

When I got my first JBI, it had a 12hp Briggs instead of the 14 horse it came with.  It had no issue with power at all and would handle dumping the hydro full tilt in most any pull situation.  It would of course bog, but quickly recover. These hydro's will pull an engine down though, and will even pull the Kubota down (hydro squealing like a pig), so I think the engine just doesn't have it's full power for whatever reason as it shouldn't pull down that easily.  You might wanna re-check your valve clearances too.

  With my diesel JB, while still fitted with the OE hydro, with all my weights it could hardly spin.  The hydro would pull the diesel down quite a bit, but it would just slow the travel speed from the pressures bypassing in the hydro from the extreme pull against it with the 25hp diesel pushing.  If you did decide to fit a diesel, I would not go past 14 to 16hp, as the hydro just can't handle much more and hold up well.


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#36 olcowhand OFFLINE  

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Posted April 16, 2013 - 08:47 PM

I wish we could hear from some very early John Deere 140 owners to see how they acted with this same hydro system.


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#37 DH1 OFFLINE  

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Posted April 16, 2013 - 09:22 PM

As promised I got some video of what the engine / hydro is doing. 

 

We hooked the hog to a tree stump and I had the throttle around 1/4 throttle the first try and then I increased it to around 1/2 throttle for the second pull. I had dad shoot the video at the carb so you could see the governor movement. Thought that might help with the diagnosis. At the end of the video I drove up the small hill I mentioned earlier in the thread. Started up the hill at about 1/4 pedal and then floored it and the first try it bogged down a little and the second attempt it really bogged down.

 

Does it do it at FULL throttle?


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#38 MH81 OFFLINE  

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Posted April 16, 2013 - 09:43 PM

Once my fat arse climbed on it then it would bog down.


Wouldn't you? :rolling:

George, I hope it ends up being one of those goofy little things.

Guys, I had my hands on the main jet adjustment. I did the coarse tune of 1.5 turns and had him start it and then rev it. It had more snap and power at just shy of 2 turns, more like 1.75... But if I went over two, it started to get sluggish, sound labored, and smell like unburnt gas.... Like me on Three Bean Chili Nite.
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#39 chris m OFFLINE  

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Posted April 16, 2013 - 10:31 PM

This one is driving me nuts too lol. I think I have watched the video 100 times already.

 

When you put the governor rod on, did you set it by the book or just put it back the way it was before you tore the engine apart?

Even though it is working, I see it is at the end of the threads on the rod, and the engine Scott has, the rod has more threads showing coming out of the threaded piece (on the throttle shaft).???

 

Even though it could be any number of things, I keep leaning to it being a carb and or governor issue?? But I could be wrong.

 

BTW what type of ignition is this. Battery or Magneto??


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#40 HowardsMF155 OFFLINE  

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Posted April 16, 2013 - 11:09 PM

Again, George, this is sounding very much like what I went through with my Massey and the Tec and that ended up being a spark/timing issue.  If you have a way to put a timing light on that engine, I'd try that very next thing.

 

PS: Right down to the throttle being wide open and the governor kicking in.  One of the first things I did was put a cable on the throttle arm so I could make sure it opened right up, and it was.  Then checked the valves, then finally the timing, and this was on the solid state type.


Edited by HowardsMF155, April 16, 2013 - 11:15 PM.

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#41 NUTNDUN OFFLINE  

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Posted April 17, 2013 - 05:25 AM

Does it do it at FULL throttle?

 

Yep. Same thing at full throttle. I just didn't put it to full throttle when making the video because of the noise. I actually think it is worse at full throttle. 



#42 NUTNDUN OFFLINE  

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Posted April 17, 2013 - 05:25 AM

This one is driving me nuts too lol. I think I have watched the video 100 times already.

 

When you put the governor rod on, did you set it by the book or just put it back the way it was before you tore the engine apart?

Even though it is working, I see it is at the end of the threads on the rod, and the engine Scott has, the rod has more threads showing coming out of the threaded piece (on the throttle shaft).???

 

Even though it could be any number of things, I keep leaning to it being a carb and or governor issue?? But I could be wrong.

 

BTW what type of ignition is this. Battery or Magneto??

 

 

It is battery ignition. 



#43 NUTNDUN OFFLINE  

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Posted April 17, 2013 - 05:28 AM

Again, George, this is sounding very much like what I went through with my Massey and the Tec and that ended up being a spark/timing issue.  If you have a way to put a timing light on that engine, I'd try that very next thing.

 

PS: Right down to the throttle being wide open and the governor kicking in.  One of the first things I did was put a cable on the throttle arm so I could make sure it opened right up, and it was.  Then checked the valves, then finally the timing, and this was on the solid state type.

 

I am going to try and get the timing light on it. Although I don't have a timing light like the one you are supposed to use. The only one we have is one that you put ends on the battery and the other on the spark plug. I might have to use my ohm meter or continuity tester to test when it breaks contact.



#44 HowardsMF155 OFFLINE  

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Posted April 17, 2013 - 11:06 AM

I am going to try and get the timing light on it. Although I don't have a timing light like the one you are supposed to use. The only one we have is one that you put ends on the battery and the other on the spark plug. I might have to use my ohm meter or continuity tester to test when it breaks contact.

Any thing that will strobe, which is what I think you are saying you have, will work.  Find a way to mark when spark should occur, chalk, spray paint, nail polish will all help you mark.  A little bit out of time probably won't matter, but I'm thinking you are going to find spark is way out--like an inch or more around the flywheel off.


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#45 olcowhand OFFLINE  

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Posted April 17, 2013 - 11:14 AM

If it isn't out of time, is there a possibility the cam is one tooth off?  I once didn't have enough slack out of a timing chain on a Honda SL125 when I timed the cam, and it would run, but was real weak.  Otherwise it sounded fine.  I finally found I was one tooth off.  Corrected it & all was great again.


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