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The High screw is always furtest from the machines cylinder

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The letters on the screws represent High (H), Low (L) and Idle (T). The H screw regulates the Air/Fuel mix during high RPMs, while the L Screw does the same during low RPMs. The T screw regulates how much fuel is sent to the carburettor while idling until the throttle is pressed.
Forms of adjusting screws

This draw down causes the cutter to be drawn down as well. For this we have two types of adjusting screws: HMA/HDA solid type and NBA rubberized type.

They are typically labeled L (low speed jet), H (high speed jet), and I (idler jet).
Turn the high speed or main jet screw clockwise until the engine begins to slow. Then, turn the screw the other way until the engine begins to slow. Turn the screw back to the midpoint. Once adjusted, check engine acceleration by moving the throttle from idle to fast.
They are designed to secure objects by removing materials while simultaneously creating helical grooves. Fine adjustment screws serve this same purpose, but they feature a unique design that distinguishes them from other types of screws.
An air fuel mixture screw is a special screw on an engine`s carburetor that controls how much air mixes with the fuel. Adjusting this screw changes how fast or slow an engine idles and how smoothly it runs.

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ANSWER : All the pictures I have of this carb show two adjusting screws.

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Rct3100 edge trimmer, how many turns of the mixture screws for normal running ?
ANSWER : Gently turn the needel valves all the way in and the back them out 1 and 1/2 turns each. Then you you make adjust ments depending on how the saw runs. If it runs fine at idel the low jet is fine. If it does not run at high speed adjust the hi jet.

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How do you adjust the high speed mixture screw? I have a Ryobi RLH1100a MK III 31cc line trimmer, and after changing the fuel lines, it will start but not idle more than about 3 – 5 seconds before it stalls. My manual points to the carby and any adjustments I have done have not helped. The manual specifies adjusting the idle mixtures 1 1/2 turns counterclockwise after screwing it in all the way, but no adjustment for the high speed adjustment stating ” no high speed adjustment is possible”, however there is a taller adjustment screw. Does anyone know how many turns this high speed adjustment screw should be unscrewed to start with?
ANSWER : Hi montex124, I will try to help. In the past few years carb makers have been making changes. Some carbs have no adjustment at all, the ports are all fixed inside the carb. Other carbs have only the idle speed mixture screw that can be adjusted, like yours seems to have. Is this screw you mention at the top and completely outside of the carb to adjust the throttle? If it is it’s probably the idle speed screw which can be adjusted to any idle speed you want and has nothing to do with the air fuel mixture but If it is right next to the idle mixture screw, it might be the high speed mixture screw but is capped so it can’t be adjusted. The low and high speed mixture screws should be marked next to each screw H and L.The 1 1/2 turns suggested is sometimes just right but other times has to be adjusted, so you can try adjusting it to get your idle but maybe adjust the idle speed screw first to get a higher RPM so it doesn’t stall on you. Like I said earlier it just adjusts the throttle, and is like when you are using it, and giving it gas as they say. I hope this helps just a bit. Regards and good luck. Get back to me if you need more help or just let me know how you did. Denis.

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Trimmer takes a long time to warm up. Cuts out when under full trottle and will not idle. Which screws are high and low speed adjust? There are two of them side by side. Do U need a special tool to adjust hi/lo speed screws?
ANSWER : Sounds like the carb needs cleaning, it is staying on choke to long. I would not bother the screws, or either a hose for the gas flow is bad.

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What is correct adjustment for high and low scews
ANSWER : With the saw warmed up adjust the low for best idle.Adjust the high for best speed then adjust a little richer from that point.Caution……Running at best speed (power) settings which is “lean” will 90% of the time burn the piston……thats why you go a little richer on that setting.

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Need to know what the carb adjustments are for a model 61 husky
ANSWER : Low side one turn out from bottem.high sie is the same.after saw is running readjust both high and low.make sure the side dosen’t go in any more then 3/4 of a turn out……if it does you will burn up the saw….

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Base adjust. on carb high and low needles on carb polen 42 18″ thanks
ANSWER : The standard setting on needles is to screw them in all the way and then back them out 1 and a half turns.

You need to set the mixtures for the carburetor. You will find a Low and High adjustment screw. turn the low adjustment screw out. You will notice that the rpms should start increasing. keep turning it out until the rpms start to drop then turn it back in a quarter of a turn. You may need to readjust the idle speed so the chain doesn’t turn during idle. Do the same for the high adjustment screw.

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Rpm fluctuates idles high then low high then low
ANSWER : It could be the governor spring is weak. Get your model type and code numbers off the engine shroud and take them to your local small engine repair shop and get the new spring. It’s not hard to replace. Install the new one and you should be up and running.


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