PRO

How to adjust your Ryobi carburettor mixture screws

Having had some running issues with my own Ryobi strimmer 2 stroke engine, i thought i would create this post for others in the same predicament. In my case the engine didnt want to idle for more than a few seconds when cold and would bog down when revved, plus when warm, it didnt seem to be achieving maximium revs anymore. Its worth mentioning that before making any carburettor adjustments you should check the spark plug and regap or replace as necessary, check/replace the airfilter if fitted, any fuel filter and if fitted the spark arrestor in the exhaust, as this alone can cause poor running if it is coked up with exhaust deposits from the engine. That said it could be a poorly adjusted carburettor thats causing the clogging on the spark arrestor in the first place!

The carburettor mixture adjustment screws on the majority of Ryobi 2 stroke engines have manufacturer designed anti tamper screw heads, known as 'pacmans' because of the mouth like triangular cutout on the screws head. The necessary drivers for these screws are unavailable or extremely difficult to source from Ryobi and i was unable to get hold of any from elsewhere, so the following pictures explain how to overcome this.

 

I neglected to take a before picture so this first image shows the screw heads with a slot already cut into them using an open ended junior hacksaw, see the last picture for a shot of the hacksaw i mean. You will need to remove the carburettor from the engine as access is way too restricted while it is still attached, just remove the two bolts holding it onto the engine and be careful not to damage the gasket that goes between the carburettor and the engine.

 

You can see i have cut through the aluminium housing and into the screw heads, to make the slots so that a normal screwdriver can be used for any future adjustments. Obviously you want to get these as central as possible so go easy and dont rush. I was being careful but still managed to cut slightly off centre!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Once the slot is deep enough, and it doesnt take much as the screws are easy to turn in small increments with very little force. Bolt the carburettor back onto the engine, remembering to use the gasket and reinstate any air filter etc.

Now start the engine and warm it up, adjust the idle screw so the engine ticks over at slightly higher revs and doesnt stall. Then while the engine idles, slowly adjust the low speed jet clockwise and/or anticlockwise until the engine runs and sounds as smooth as possible when you rev it. In the picture you can see the L stamped on the carb to identify the slow speed jet adjuster screw, this is the one on the left nearest the engine. You may have to restart the engine several times during the adjustment process.

Now hold the engine at full throttle and adjust the other screw, the fast speed jet adjuster, again until the engine runs and sounds smooth with no 'bogging down'

The engine should now idle and run/rev with no hesitation or bogging down, you will probably need to back off the idle screw a little to drop the revs back to or close to where they were before.

 

 

You can see in the above picture, with the carb back on the engine i had to adjust it by only an eighth anti clockwise for the low speed jet and a quarter turn clocwise for the high speed jet to make all the difference.

 

This is the open ended junior hacksaw i used, which is ideal because of the available access even with the carb off the engine and the obvious difficulty in using a normal full framed hacksaw.

Votes: 0
E-mail me when people leave their comments –

Comments

  • Just to add to this helpful article, the "pacman" adjusters can be obtained for about £5 from Amazon.

    I now have one and am going to try this procedure to fix my hard-starting Ryobi.

    Thanks.

This reply was deleted.

You need to be a member of Landscape Juice Network to add comments!

Join Landscape Juice Network

Open forum activity

Harry@VWGS replied to Tony @SM's discussion Stihl HLA85, Long reach trimmer.
"I went into my dealer yesterday and was shown that even if they would/could fix the machine, Stihl haven't got the parts needed in stock.. not good in my opinion, but I'm guessing over the next year or so companies are all going to struggle. "
6 hours ago
Dave Colton replied to Tony @SM's discussion Stihl HLA85, Long reach trimmer.
"Try the dealer you got it from, mine did this and like yours was one month out of warranty but Stihl still honoured it."
7 hours ago
John F replied to Fleur Voice's discussion Will you or have you increased your rates post-covid to make up for lost revenue during the pandemic?
"It was an interesting time initially , I took the opportunity to re sett my customer base and weed out the unproductive jobs and i think equally one or two used it as an opportunity to sack me off to find a cheaper service . 
One job was an annual…"
8 hours ago
John F replied to Harry@VWGS's discussion Stihl HLA 86 needed.
"Which cordless models are classified as industrial as opposed to domestic ? and which components set the two apart . ? 
I was always told by dealers it is down to the quality of the gearbox with fuel driven hedgetrimmers .
 
 
 "
9 hours ago
Robbie posted a blog post
9 hours ago
Billybop replied to Harry@VWGS's discussion Stihl HLA 86 needed.
"yes so many completely different models now with slightly different references. For example HLA56 and HLA65 so easy to confuse if one digit is transposed, both long reach hedge trimmers but they don't use the same battery type even. Often see…"
12 hours ago
Keith replied to Fleur Voice's discussion Will you or have you increased your rates post-covid to make up for lost revenue during the pandemic?
"I had a few 'nervous' clients at the beginning who paused the work initially, but within a few weeks changed their minds after seeing their lawns getting out of hand ..I just encouraged them to pay by bank transfer ..skip the drinks etc…"
12 hours ago
Vic 575 replied to Fleur Voice's discussion Will you or have you increased your rates post-covid to make up for lost revenue during the pandemic?
"Most of us on here just carried on as normal throughout Covid. All my work continued as before. A large part of it is commercial work, but then all the domestic ones were also unaffected. The grass and the hedges still needed to be cut.
I would be…"
13 hours ago
Neil Darby replied to Fleur Voice's discussion Botanical Sexism and the Rise of Hay Fever
"The long covid effected my lung capacity for about 8 months, until January plus fatigue etc. I still get brain fog, annoyinly mostly plant names!
This also effected my mental health ( I have underlying issues) & had an affect on the regular…"
15 hours ago
Fleur Voice replied to Fleur Voice's discussion Botanical Sexism and the Rise of Hay Fever
"I had never heard of botanical sexism before but it explains so much! It's awful isn't it, I suffer really badly from allergies too, so I can empathise. Do you still feel the effects of long covid even now? I imagine everything contributes really,…"
15 hours ago
Tony @SM posted a discussion
I have been over the moon with this piece of kit.....until yesterday. It simply wouldnt go. I checked the grease as it hadn't been used for a while but that was fine. The gear moved when I manually rotated it. An hour later, it worked so I thought…
15 hours ago
Etesia UK posted a blog post
Martin Carty, Managing Director at Carty Services, has revealed how a 0% interest finance offer from Etesia UK enabled him to improve operations on a wide range of school playing fields throughout Warwickshire. During last year’s uncertainty and…
19 hours ago
JJ Gama replied to Fleur Voice's discussion Will you or have you increased your rates post-covid to make up for lost revenue during the pandemic?
"We increased our rates marginally but that was combined with an increase in the demand as restrictions on were eased. I think most the other companies around us did the same thing so it worked out but still, nice little way to recoup some covid…"
yesterday
David Benson replied to Harry@VWGS's discussion Stihl HLA 86 needed.
"i just gogeld it this is the first one i looked at 
just realised might be the wrong model"
yesterday
David Benson replied to Harry@VWGS's discussion Stihl HLA 86 needed.
"STIHL HSA 86 Cordless Hedge Trimmer 18" | STIHL Hedge Trimmer – Sam...
this site says it will deliver by monday"
yesterday
David Benson replied to 1st Garden Maintenance's discussion How to Value a Landscaping Business.
"dont know if i am working things out wrong but it would take 60 years of proffit to pay for the 750.000 dont get how the value is reached "
yesterday
More…