lawn boy 8237 rpm adjustment

impalass

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I noticed that the rpm increased on the the engine and i tried to reduce the rpm by the collar and nothing happened. One odd thing is when i remove the air filter element the rpm dropped about 400 rpm. When i move the throttle from high to low nothing happens. The carb has a main jet adjustment for the fuel. this is a f-engine.
 
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robinb66

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On the F series engines there is no throttle rpm adjustment, there is a small set screw on the side of the body called an atmosphere adjustment screw. According to the manual to adjust turn all the way in then open a half turn start it up and let it run till it's warm, if not running right turn another half turn and wait five minutes. Do this till she runs right or until she runs at the speed you need. Also you say she drops in RPM's when you remove the filter. it sounds like you might need to clean your carb, seeing as how she has higher rpm's with the filter then it sounds like she's starving for gas, just my opinion. Hope this helps!!:thumbsup:
 

WhyZed

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Depends on the model of carburetor if it has altitude adjustment or not.
My F models carb, I have a main jet adjustment and no adjuster for altitude.
On my D409, I have an altitude adjuster and no main jet adjuster.
These adjusters are for fine tuning and not rpm control.

On my F, the RPM adjustment is the wind vain governor. There is a white plastic wheel adjuster on top of the carb, under the flywheel.
On this model, I turn this white wheel counter-clockwise and my RPM increases, clock-wise decreases (or the other way - doesn't matter) 50rpm per click and it works good.

I have my D409 apart right now and can see the governor system it is totally different, I don't see an adjuster but haven't looked to had yet.

There is a round metal flap in the air venturi in the carb. The lever or mechanism that moves that flap is your rpm/speed/throttle.
 

WhyZed

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Last edited by impalass; Today at 01:08 PM.

When you re-word your entire post and ask a different question then the original posts question was, it's hard for others that might have the same question find the answer they are seeking. :thumbsup:

The reason engines increase in rpm is do to more air (more air in the air to fuel mixture) entering the combustion chamber, period. An engine will run it's fastest just before it seizes.
The main jet should be adjusted a bit richer than serging for highest power. The man jet should be adjusted for optimum performance only after the engine, including the air/fuel/spark/exhaust are optimal. The main jet adjustment is not a bandage adjuster, it is a fine adjustment for a healthy engine.

Temperature is a big tuning 'if'. If the motor was running perfect in hot sticky weather and suddenly it is cold outside, the motor could be now running lean.

There is a chance a spec of dirt has clogged an orifice in the carb. Clean it first.

Take the cowling off and make sure the wind vain is free.
 

impalass

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When you re-word your entire post and ask a different question then the original posts question was, it's hard for others that might have the same question find the answer they are seeking. :thumbsup:

The reason engines increase in rpm is do to more air (more air in the air to fuel mixture) entering the combustion chamber, period. An engine will run it's fastest just before it seizes.
The main jet should be adjusted a bit richer than serging for highest power. The man jet should be adjusted for optimum performance only after the engine, including the air/fuel/spark/exhaust are optimal. The main jet adjustment is not a bandage adjuster, it is a fine adjustment for a healthy engine.

Temperature is a big tuning 'if'. If the motor was running perfect in hot sticky weather and suddenly it is cold outside, the motor could be now running lean.

There is a chance a spec of dirt has clogged an orifice in the carb. Clean it first.

Take the cowling off and make sure the wind vain is free.

I said when i remove the air filter element the rpm drops not increases. I had the carb apart and it is clean and when i reinstall the carb the vane is free to move.
 

WhyZed

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Ya, I read that..

Is it consistent? Can you put the filter back in and raise the rpm? Can you remove it again & recreate the change?

Knowing this and we will try to help you get your mower fixed up. :thumbsup:
 

impalass

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Ya, I read that..

Is it consistent? Can you put the filter back in and raise the rpm? Can you remove it again & recreate the change?

Knowing this and we will try to help you get your mower fixed up. :thumbsup:

Yes it is consistent. Even with the filter removed the rpms do not change when i move the throttle lever back and forth.
 

WhyZed

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Morning,

Can you see the butterfly in the carb venturi?
Can you move the lever that the butterfly is attached to and change the rpm?
 

impalass

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Morning,

Can you see the butterfly in the carb venturi?
Can you move the lever that the butterfly is attached to and change the rpm?

That is the lever i am referring to. One end of the spring is attached to the lever and the other end of the spring is attached to the round collar.
 

WhyZed

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Can you open & close the butterfly and change the rpm?
Did this problem start after you took the carb off?

There is a Dude on youtube named jon3800, I think you are having the same problem he was having. He found the lever that's links the carb to the governor was flipped over and locked fwo (full wide open).

As much detail as possible. The air filter scenario is pretty strange, if the filter is touching (opening) the butterfly when you put it in could be what is raising the rpm when installed.
 
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