Briggs fuel/air mixture issue

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Smokeeater

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Still working on this 287707 1274-E1 14hp engine with auto choke, not manual

Carb replaced
RPM is set now

Problem I'm having is I turn clockwise the fuel mixture screw till it almost cuts out, but when I go counterclockwise to find the other cut out point (then set it in middle), it won't cut out. I can almost unscrew the thing and it keeps running.

Now when it cold starts you have to keep choke on for quite a while till it warms up to not stall

Any help is appreciated
 
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Rivets

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Try this procedure.
[FONT=&quot][FONT=&quot]Adjusting a carb[/FONT][/FONT]
[FONT=&quot][FONT=&quot]This is the procedure I always taught my students to adjust a carb with two fuel controlling needles.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]1. Start the engine and move the throttle control to top speed.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]2. Adjust the high speed needle (this is the one under the float bowl) clockwise very slowly until the engine starts [/FONT][/FONT]
[FONT=&quot][FONT=&quot] to bog down.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]3. Back the needle out 1/8 turn, the engine should now run smoothly.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]4. Now move the throttle control down to idle. If the engine stalls out turn the idle speed screw in one full turn,[/FONT][/FONT]
[FONT=&quot][FONT=&quot] restart the engine and bring the throttle control down to idle. If the engine is running to fast, turn the speed [/FONT][/FONT]
[FONT=&quot][FONT=&quot] screw slowly out until the engine seem to want to die and then in 1/8 turn.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]5. Now with the engine running, adjust the idle needle out until the either gains in RPM's or starts to bog down. If[/FONT][/FONT]
[FONT=&quot][FONT=&quot] the engine gains in RPM's, continue to adjust out until the engine starts to bog down. At this time turn the [/FONT][/FONT]
[FONT=&quot][FONT=&quot] screw in 1/4 turn. Now the engine may be running to fast, so turn the idle speed screw out until you get an [/FONT][/FONT]
[FONT=&quot][FONT=&quot] RPM you like.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]6. Now you must repeat step 5. If the engine bogs down right away turn idle needle back in to your starting point [/FONT][/FONT]
[FONT=&quot][FONT=&quot] and go to step 7. If it speeds up, repeat step 5 again.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]7. Turn idle needle in until the engine bogs down and then out 1/8 turn.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]8. Now the engine should run smoothly at all speeds.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]9. To check, set the engine to idle, then quickly push the throttle control tohigh speed. If it dogs and does not [/FONT][/FONT]
[FONT=&quot][FONT=&quot] come to speed, open the idle needle 1/8 turn and repeat.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]10. Set to go.[/FONT][/FONT]
[FONT=&quot][FONT=&quot][/FONT]
[/FONT]
[FONT=&quot][FONT=&quot]There are 2 reasons I have it done this way is, first the high speed needle controls the fuel going to the low speed circuit and second is that the idle needle controls how much fuel is used when going from idle to high speed. You should also review the section in the manual I posted before starting this procedure.[/FONT][/FONT]
[FONT=&quot]
[/FONT]
 
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Smokeeater

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Rivets said:
Try this procedure.
[FONT=&quot][FONT=&quot]Adjusting a carb[/FONT][/FONT]
[FONT=&quot][FONT=&quot]This is the procedure I always taught my students to adjust a carb with two fuel controlling needles.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]1. Start the engine and move the throttle control to top speed.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]2. Adjust the high speed needle (this is the one under the float bowl) clockwise very slowly until the engine starts [/FONT][/FONT]
[FONT=&quot][FONT=&quot] to bog down.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]3. Back the needle out 1/8 turn, the engine should now run smoothly.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]4. Now move the throttle control down to idle. If the engine stalls out turn the idle speed screw in one full turn,[/FONT][/FONT]
[FONT=&quot][FONT=&quot] restart the engine and bring the throttle control down to idle. If the engine is running to fast, turn the speed [/FONT][/FONT]
[FONT=&quot][FONT=&quot] screw slowly out until the engine seem to want to die and then in 1/8 turn.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]5. Now with the engine running, adjust the idle needle out until the either gains in RPM's or starts to bog down. If[/FONT][/FONT]
[FONT=&quot][FONT=&quot] the engine gains in RPM's, continue to adjust out until the engine starts to bog down. At this time turn the [/FONT][/FONT]
[FONT=&quot][FONT=&quot] screw in 1/4 turn. Now the engine may be running to fast, so turn the idle speed screw out until you get an [/FONT][/FONT]
[FONT=&quot][FONT=&quot] RPM you like.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]6. Now you must repeat step 5. If the engine bogs down right away turn idle needle back in to your starting point [/FONT][/FONT]
[FONT=&quot][FONT=&quot] and go to step 7. If it speeds up, repeat step 5 again.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]7. Turn idle needle in until the engine bogs down and then out 1/8 turn.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]8. Now the engine should run smoothly at all speeds.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]9. To check, set the engine to idle, then quickly push the throttle control tohigh speed. If it dogs and does not [/FONT][/FONT]
[FONT=&quot][FONT=&quot] come to speed, open the idle needle 1/8 turn and repeat.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]10. Set to go.[/FONT][/FONT]
[FONT=&quot][FONT=&quot][/FONT]
[/FONT]
[FONT=&quot][FONT=&quot]There are 2 reasons I have it done this way is, first the high speed needle controls the fuel going to the low speed circuit and second is that the idle needle controls how much fuel is used when going from idle to high speed. You should also review the section in the manual I posted before starting this procedure.[/FONT][/FONT]
[FONT=&quot]
[/FONT]
Click to expand...

There isn't one on the bottom of the bowl, its a solonoid
 
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Rivets

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Sorry I didn’t check which carb you had. I now see it is either a Nikki or LMT. Either way the needle you are adjusting is only for the idle circuit and should be adjusted just as I posted. This means that you need to have the fixed jet high speed circuit working properly first. You say you have high speed RPM’s set, if so start at step 7. You said you replaced the carb. Did you use an OEM carb or a substitute off the Internet? I’ve seen more than once carbs not purchased from know sellers are not new, have parts missing, bad internal parts, or parts assembled wrong. Unless you know what you are looking for, most people would never know it.
 
tom3

tom3

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Some of the newer carbs don't have any actual adjustments for mixture, just a screw that adjusts the air bleed into the float bowl. Weird deal for sure but I guess this controls emissions from the bowl from the gas evaporation? Usually adjust about 2 turns out. Sure be nice to have fully adjustable carbs on the new motors I think, but we're now seeing engines that you don't even change the oil in. Modern technology (crap).
 
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Smokeeater

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I have to say Rivets...I did a carb kit install with new needle and seat, but after a while I noticed the throttle wasn't closing fully, so I thought I'd try a new carb instead. New from JD is $250 Cdn..So I just bought one from Amazon and it was just to see if my previous problem disappeard and it did, so I was going to keep this carb. But now I'm wondering too if it's the quality

I got needle to bog down and then I went out 1/8th turn, went to high idle and it still pops and sputters, but only high not low idle...I'll try to keep adjusting additional 1/8th turns to see
 
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Smokeeater

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I've turned it back 1/8th turn like 20 times checking each time, nothing has changed
 
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Rivets

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Sounds to me like the high speed circuit is plugged or has the wrong jet in it. One other thing, have you checked to be sure you have no leaks between the carb, manifold and engine block?
 
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Smokeeater

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Rivets said:
Sounds to me like the high speed circuit is plugged or has the wrong jet in it. One other thing, have you checked to be sure you have no leaks between the carb, manifold and engine block?
Click to expand...

Ahhhhh Rivets....
So I just came on here to say I had it on high idle and sprayed carb cleaner around it to see if there's a vacuum leak. Well,as soon as I sprayed between carb and exhaust intake it smoothed out. (Just as you said above). I guess I was trying to get more fuel to catch up to air, but I just had to stop the air now that I found that
So I used the carb that came with the Amazon carb and even removed it and put a little oil on it to make sure it wasn't dried out but it didn't work. So I've ordered a couple gaskets that show for the engine. Problem is all diagrams don't have an "offbrand" carb, so I'm going by same shape and see.
 
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nbpt100

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If you are in a pinch you can make a temporary gasket out of a cereal box.

Rivets, your procedure seems to make sense as you explain it. For what ever reasons I was taught to start wit the idle circuit adjustment and then adjust the high speed jet. Repeat as needed. Since the high speed needle does control the flow to the idle circuit what you describe make sense.

On a 2 cycle diaphragm carb would you do the same? I am not 100% sure it applies in the same way. What do you say to that?
 
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