How to adjust the low and high settings on the carb

Implies carburetor low speed fuel circuit lean. Increase low speed fuel/air.

Initial setting is 1 1/2 turns. Increase idle speed enough to keep the engine runnning so a proper adjustment of the low speed air/fuel mix can be completed.

Basic rules; Always adjust low speed a/f first, then open throttle and adjust high speed a/f. Any low speed adjustment must be followed with a high speed adjust. Error on the rich side for high speed. Allow engine to reach operating temperature for final adjustment.

Other potentual issues, fuel quality, fouled carburetor, old impulse diaphragm (carb), carb to engine intake gasket leak, crankcase leak.

Removing tines makes it easier (safer).

Set both the high and low mixture settings two full turns back from the closed setting(full clockwise).. Set idle speed for all ahead full.

Start sucker and after a warmup throttle it down and then start adjusting the low mixture screw for fastest idle. Then lower idle some more but not to point where it starts to run rough. Then rev the sucker to high speed and adjust the high mixture for max speed. You may have to make a slight adjustment on the high speed to get a smooth transition from low speed to high.

The carb is factory set you need to remove carb you will then see two screws one marked L and the other H with a small hacksaw cut a slot across both screws don't worry about cutting into carb body this can't be helped screw both screws fully in then back them off 1 and 1/4 turns this rough sets high and low running start saw set low speed first adjust screw in or out to get best low running then rev saw to max.and adjust max revs do the same as you did with the low speed screw to obtain max revs this should solve your problem.

I haven't heard of Ryobi using a carb different to most similar machines which use a small diaphragm-type carb which uses suction impulses from the 2-stroke engine crankcase to lift fuel from the fuel tank into the carb. There is generally one screw which is a throttle stop and two screws which are fuel volume screws; one with a greater influence at low speed and idle and one with greater influence at high speed. The low speed screw does have some influence at high speed and the high speed screw does have some influence over low speed fuel mixture.

The basic settings of the screws should not be lost and if stripping and cleaning the carb each screw should before removing be carefully turned in, counting the turns, until it bottoms so after cleaning it can be returned to its former position.

The amount of adjustment from the position the manufacturer set each screw to would typically be in the order of plus or minus one-eighth of a turn and if adjustment of more than about a quarter-turn is needed it could indicate the carb needs a thorough clean.

Making an adjustment of one screw means adjustment of the other is almost inevitable. The basic requirement is for the machine to work under load efficiently at high speed and it is usually desirable the machine will be capable of idling. Obtaining both is rather a balancing act and will need some patience and time making minor adjustments of each screw and in practice some compromises must be made and if hard work at speed has been achieved it usually doesn't pay to try too hard to achieve a smooth idle.

Most of carburetor has three buttons to adjust. L (low), H (high) for fuel injection at low and high speeds. There is also a minimum (the chain must be stationary if it is well tuned). The chainsaw is set at low rpm throttle with screws ( L ), and its vivacity is set at high speeds ( H screw ). In the beginning is good put both to set at 1.5 turns from full closure. And then, if the chainsaw starts, you can adjust a carburetor work. Careful with adjusting with H due to high speed.

Starting with the question which screw is which: the low speed screw is closest to the engine and that makes the high speed screw farther away. Set the screws 1 turn out and then adjust as needed.

Try when idle to adjust the carb settings.There has to be 2 screws to adjust the low and high.The low is for when the saw is in low at speed or when is not in use for cut.When you pull the handle to start cut then the adjust the high one at max speed.


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You should have a High Speed carb adjust and a Low Speed carb adjust. If it's running fine while idling, adjust the high speed setting. If you have two nobs, its the lower one. May be set wrong. If you don't have two nobs, remove the carburator and check the jets to make sure they are completely clean or better yet, order yourself a carb rebuild kit to take care of all of this. I just rebuilt my 1971 evinrude 4hp and the carb kit made the world of difference.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/matthew_d24b835e574ef6ca

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.

yes, you need to tune the carbs, by adjusting the low and high speed jets. there should be to slotted screws on the carbs, this is an older m/c, that is the set up. start bike and try tuning them. the carbs may need cleaning if you cant adjust