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Discussion Starter #1
I got this Ariens ST824LE from my brother, who recently bought a new Ariens Deluxe 30.

This Ariens has the old school Tecumseh (Cast Iron Bore) engine. He told me that the engine was not running well and he was advised by a mechanic to get a new machine (thus the Ariens 30). I told him that I would take a look at the old Ariens and see if it could be fixed up and sold.

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Looks to be in really good shape for a 15 year old machine. The engine does run like poo, but i'll see if I can get it running right.

First steps are to do a little bit of decarb on the combustion chamber and run some fuel system cleaner, then do a compression and cylinder leak test to see where we are at . . .
 

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mechanics are not the best person to take advice from regarding small engine machines, more than likely just needs a carb clean
 

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Discussion Starter #5
Thanks, guys. I was surprised that it is in such good shape. The engine does run badly. So far, I have disassembled and cleaned the carb, which was very clean already,

I ran a compression test (had to use the pull start as the electric start is not engaging) I did not get much compression . . . maybe 25 lbs. I did a cylinder leak test and got only 4% leak, which is good for a 15 year old engine. I think I'll revisit the compression test to see if I get the same results.

Right now, I'm doing an oil change, just because it does not look like it had one recently.

The engine starts fine . . . 1-2 pulls. But it 'studders' quite a bit throughout the throttle range, like its trying to run smoothly, but just can't quite seem to do so.

So, maybe timing ???

Maybe the compression release cam is not disengaging??? I assume that works off of the pull cord ???

The exhaust is clear . . . not sooty.

When I pull the spark plug after running, it is wet, which may indicate a rich mixture.

The carb has no adjustments.

Thoughts?

It would be a bummer if I could not get the engine sorted out and had to buy a replacement engine. (there goes the profit margin)
 

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See if you have carbon deposits on the valves/seats. They could be causing the low compression due do the valves not seating well. I had a rough running machine that I cleared up with some intense Sea Foam applications.
 

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Discussion Starter #7
See if you have carbon deposits on the valves/seats. They could be causing the low compression due do the valves not seating well. I had a rough running machine that I cleared up with some intense Sea Foam applications.
Yes, I did check the valve seats, and instead of SeaFoam, I used a mix of acetone and ATF in the combustion chamber to clear out some carbon. The area around the valves did look better afterwards. Also, I would not have gotten good leak test results if the valves were not sealing tight.

FWIW - I made a short video on the engine running at various stages throughout the throttle range. There is a bit is 'clacking/ringing' noise that you can hear at the lower RPM's. I used my mechanics stethoscope to isolate that extra noise to the muffler. Sort of makes me think that there is a baffle that has come loose in the muffler. . . . could be messing up the engine performance. Max RPM is 3475-3500 as per my digital optical tach.

Here is the link to the video. . .

 

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Discussion Starter #9
Here is the sticker from the engine, in case that is useful information.

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Tec HMSK80 155668V
 

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See if you have carbon deposits on the valves/seats. They could be causing the low compression due do the valves not seating well. I had a rough running machine that I cleared up with some intense Sea Foam applications.
Another way to clean the valves and seats is with some carb cleaner, a variable speed drill and a 'brass wire' rotary brush. Insure it's really brass wire and not brass covered steel wire. First I do the piston top and inside of the head using carb cleaner and the wire brush. With both valves closed, I hit the tops of the valves using the carb cleaner & brush. Next roll the engine so one valve is open and do the same thing hitting the underside of the valve. Roll the engine so the other valve is open and do it again. Once it's all done hit everything with carb cleaner and wipe up all the leftovers. Final step I do is spray it down with some WD40 and wipe it around to insure you have a thin coat on the cylinder walls and piston. You should have a fully decarb'd engine at this point, just reassemble it if everything else is done.
 

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Discussion Starter #12
Yes, I recall seeing a black cap (item 20A) so I'll pop it off and clean out the idle jet. The emulsion tube (36) is brass, the o-rings may need some attention.
 

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Discussion Starter #14
All the Tec non adjustable (OEM ones) I've worked on had plastic emulsion tubes. Adjustable OEM always had brass and not removeable emulsion tubes.
It might be an aftermarket carb, since it does not have the bowl drain (items 32, 33) and it looked so clean. I'm just not sure of the machine's maintenance history.
 

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Discussion Starter #15
UPDATE:

I took out the idle adjusting needle (or whatever it is) and cleaned out the passages. They were not clogged at all. I also flushed the idle air passages with acetone. and soaked the 'needle' in acetone.

I also took off the muffler to check for the loose baffle. It seems to be the round perforated baffle at the input to the muffler. I thought that the baffle may have been loose because the muffler bolts were not very tight. So, I put the muffler back on and torqued the bolts to 25 ft-lbs.

No difference in the engine performance or sound. So . . .

I think I will order a new adjustable carb and a new muffler and see where that leaves things.

The fixed setting carb is Part # 640052/640349 The adjustable carb seems to be Part # 632334/632334A
 

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I had a similar issue with a 926 around that same year. The adjustable carb ironed it out and ran a top after. I had a couple of those machines that were 2005 ish. All ran like crap and ended up putting the adjustable carb for the fix.
 

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Discussion Starter #17
I had a similar issue with a 926 around that same year. The adjustable carb ironed it out and ran a top after. I had a couple of those machines that were 2005 ish. All ran like crap and ended up putting the adjustable carb for the fix.
Yes, I think the non-adjustable carbs only seem to work well with the OHV engines, not the flatheads.
 

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Yes, I think the non-adjustable carbs only seem to work well with the OHV engines, not the flatheads.

I’m wondering if my carb is the source of the issues I’m having. I just put a new 640349 on my 926 flathead and it ran well briefly, now it dies under load.



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Discussion Starter #19
I’m wondering if my carb is the source of the issues I’m having. I just put a new 640349 on my 926 flathead and it ran well briefly, now it dies under load.
It would be worth a try with the old style (adjustable) carb . . .
 

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It would be worth a try with the old style (adjustable) carb . . .


Agreed, I believe the carb that came on it (Ariens 926LE) was adjustable. I’ll need to get a rebuild kit for it, it was leaking gas from the bowl seal when I bought it. In the interest of time I just bought an oem replacement carb.


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