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Ryobi/Homelite Carburetor Adjustment
Hi all - I searched in this and other forums and took the info I gleaned and just completed a 1/2 hour tweaking of my 2 year old Homelite 26CC MightyLite trimmer.
This information seems to be consistent across all the Ryobi and Homelite 2-cycle home use equipment.
Common Problems: Poor or erratic idle, poor power at speed, won't run with the choke off, low power when trimming, low power or won't build rpms with upgraded (heavier) string heads, etc.
Cause: Due to national EPA rules adopting California CARB (air research board) standards, manufacturers are required to make all equipment run super lean under all conditions except full choke.
To ensure that equipment is maintained in like-new condition, the law also requires manufacturers to seal off or otherwise restrict people from adjusting carburetor settings.
Solution:
There are three screws on these Chinese Ryobi/Homelite carburetors. One is slotted for idle adjustment with a screwdriver.
The other two are located just below the throttle assembly (where the throttle cable attaches) They are tamper-proof screws that are frequently referred to as pac-man screws due to their shape.
Since the pac-man tool is $15.99 or so at eBay and other sources, it is not cost effective to buy one. Use or borrow a dremel tool instead.
For $1.99 or so at harbor freight (or with almost every standard dremel kit) you can get a small 1.5 cm diamond-grit cut-off wheel. It is usually used to cut rusted bolts or the like. These are very common and can be bought at Sears or anywhere they sell dremel bits.
First, pull the choke housing off the carburetor and remove the carburetor bolts. Note: If you don't want to, don't bother to remove the fuel lines. They can be a bit of a hassle if they are stuck.
With the carb loose, rotate it counterclockwise to get clearance, then use the cutting wheel to carefully cut a slot in each of the little pac-man screw heads. To do this you will have to also cut into the carb body where they've sleeved these screws to keep people from using pliers on them. Don't worry, these sleeves aren't functional in any way.
Before reassembling, test your slots with a nice long, small screwdriver. Be sure they rotate freely but don't do any adjusting yet. Reset them where you found them.
Reassemble.
Now - to adjust the carb, you need to know that the inside screw (toward the engine block) is the idle mixture, and the outside screw is the high speed mixture.
In most cases, you will find that about 1/2 to 1 full turn is needed with the high speed screw to get smooth powerful full-throttle with the engine warm and the choke off.
Once you've got good full throttle operation, then adjust the idle mixture to run smoothly at idle. If idling is a real problem, you should first adjust the idle to maximum by turning the idle slotted screw all the way in. Don't use much force, they can be easily overtightened and broken.
Get the idle to run smoothly at max, then lower it by backing off the idle screw. By this time the machine should be fully warmed up.
Retest it all by shutting the trimmer down and letting it sit a couple of minutes, then restart it and run it through the paces. You should not need the choke for a hot restart.
Test cold start the next day, and make any final adjustments.
Good luck and happy mowing!
This information seems to be consistent across all the Ryobi and Homelite 2-cycle home use equipment.
Common Problems: Poor or erratic idle, poor power at speed, won't run with the choke off, low power when trimming, low power or won't build rpms with upgraded (heavier) string heads, etc.
Cause: Due to national EPA rules adopting California CARB (air research board) standards, manufacturers are required to make all equipment run super lean under all conditions except full choke.
To ensure that equipment is maintained in like-new condition, the law also requires manufacturers to seal off or otherwise restrict people from adjusting carburetor settings.
Solution:
There are three screws on these Chinese Ryobi/Homelite carburetors. One is slotted for idle adjustment with a screwdriver.
The other two are located just below the throttle assembly (where the throttle cable attaches) They are tamper-proof screws that are frequently referred to as pac-man screws due to their shape.
Since the pac-man tool is $15.99 or so at eBay and other sources, it is not cost effective to buy one. Use or borrow a dremel tool instead.
For $1.99 or so at harbor freight (or with almost every standard dremel kit) you can get a small 1.5 cm diamond-grit cut-off wheel. It is usually used to cut rusted bolts or the like. These are very common and can be bought at Sears or anywhere they sell dremel bits.
First, pull the choke housing off the carburetor and remove the carburetor bolts. Note: If you don't want to, don't bother to remove the fuel lines. They can be a bit of a hassle if they are stuck.
With the carb loose, rotate it counterclockwise to get clearance, then use the cutting wheel to carefully cut a slot in each of the little pac-man screw heads. To do this you will have to also cut into the carb body where they've sleeved these screws to keep people from using pliers on them. Don't worry, these sleeves aren't functional in any way.
Before reassembling, test your slots with a nice long, small screwdriver. Be sure they rotate freely but don't do any adjusting yet. Reset them where you found them.
Reassemble.
Now - to adjust the carb, you need to know that the inside screw (toward the engine block) is the idle mixture, and the outside screw is the high speed mixture.
In most cases, you will find that about 1/2 to 1 full turn is needed with the high speed screw to get smooth powerful full-throttle with the engine warm and the choke off.
Once you've got good full throttle operation, then adjust the idle mixture to run smoothly at idle. If idling is a real problem, you should first adjust the idle to maximum by turning the idle slotted screw all the way in. Don't use much force, they can be easily overtightened and broken.
Get the idle to run smoothly at max, then lower it by backing off the idle screw. By this time the machine should be fully warmed up.
Retest it all by shutting the trimmer down and letting it sit a couple of minutes, then restart it and run it through the paces. You should not need the choke for a hot restart.
Test cold start the next day, and make any final adjustments.
Good luck and happy mowing!
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