Shindiawa T-25 Carb settings

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  #1  
Old 06-12-09, 12:39 PM
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Shindiawa T-25 Carb settings

I have disassembled and cleaned the carb and did not record the needle valve turns when removing. There are 3 adjustment screws. Main adjustment screw at the bottom, above it is the Slow Air Screw and above it is the Slow Stop Screw.How many turns from full closed is a good place to start?

Riverat
 
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Old 06-12-09, 01:26 PM
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The stop screw would be the idle speed screw. Don't worry about that just yet.

Set the other two at lightly seated. Then turn them both out 1 1/2 turns. That's a good place to start. That is almost a standard on all makes.

Set the low speed screw until the engine will accelerate the best. Then go to the high speed screw and with the throttle open set the screw for max rpms. Then go back out slightly to allow it a little more fuel to pull a load.

Then set the idle speed screw for a decent idle.
 
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Old 06-12-09, 04:39 PM
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I am thinking that you have a TK slide valve carburetor, as this is what I recall was used on the T-25.

Set the high speed at 1 1/2 turns from seat to start. The low speed is actually an air bleed and is used to bleed air at low speeds when the needle in the slide valve gets wear. This screw is normally closed, you will only adjust it if the engine runs too rich at low idle speeds, then you will open it slightly to lean the idle mixture out.
 
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Old 06-12-09, 07:50 PM
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Oops, if you have a slide carb, I'm on the wrong page. Listen to 30ytech.
 
  #5  
Old 06-15-09, 06:27 AM
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Originally Posted by marbobj View Post
The stop screw would be the idle speed screw. Don't worry about that just yet.

Set the other two at lightly seated. Then turn them both out 1 1/2 turns. That's a good place to start. That is almost a standard on all makes.

Set the low speed screw until the engine will accelerate the best. Then go to the high speed screw and with the throttle open set the screw for max rpms. Then go back out slightly to allow it a little more fuel to pull a load.

Then set the idle speed screw for a decent idle.
Thanks a million for the advise. The Shindiawa is again running wonderfully.

Riverat
 
  #6  
Old 06-20-09, 07:34 AM
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Originally Posted by marbobj View Post
The stop screw would be the idle speed screw. Don't worry about that just yet.

Set the other two at lightly seated. Then turn them both out 1 1/2 turns. That's a good place to start. That is almost a standard on all makes.

Set the low speed screw until the engine will accelerate the best. Then go to the high speed screw and with the throttle open set the screw for max rpms. Then go back out slightly to allow it a little more fuel to pull a load.

Then set the idle speed screw for a decent idle.
The T-25 at first ran great. Now, however, as it runs for 10 mins or so, it seems to run out of gas. It will sort of run if the choke is almost closed. Once running, open the choke and the rps are great and then it dies. I have noticed that the silencer (muffler) gasket is blown out.. Is this gasket necessary to give the engine enough back pressure to draw up the gasoline from the tank. The filter has just been replaced and the entire carb has been cleaned. Any ideas?

Riverat
 
  #7  
Old 06-20-09, 08:45 AM
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If it runs great for 10 mins & starts to act as if out of fuel,, Try loostening the fuel cap & see if it picks up fuel again... The vent in the cap may be plugged ... Just a guess that doesn"t cost anything to try Roger
 
  #8  
Old 06-20-09, 11:26 AM
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If the cap doesn't fix it, buy a repair kit for the carburetor. Your diaphragm which is central to the fuel pump is probably gotten stiff.

Back pressure in an engine is more of a performance issue - not a "no run".
 
  #9  
Old 06-20-09, 02:40 PM
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Originally Posted by 30yearTech View Post
I am thinking that you have a TK slide valve carburetor, as this is what I recall was used on the T-25.

Set the high speed at 1 1/2 turns from seat to start. The low speed is actually an air bleed and is used to bleed air at low speeds when the needle in the slide valve gets wear. This screw is normally closed, you will only adjust it if the engine runs too rich at low idle speeds, then you will open it slightly to lean the idle mixture out.
If this actually has a slide carb, then I don't think it has a diaphragm.
Where do you have the low speed screw set? If you set it 1 1/2 turns out, and 30year is correct, (and I imagine he is) then you may have it set too lean which can cause it to overheat and not want to run under a load...
The low speed screw may not be meant to adjust high speed but I think it can certainly effect it.
 
  #10  
Old 06-20-09, 03:37 PM
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The slide in it just takes the place of the butterfly for the throttling of the air flow. It still has a diaphragm for the fuel delivery.
 
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