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I've got a Walbro WA226 with no hi-speed adjustment screw. Unfortunately, it seems that the issue is in the high-speed jet. Adjusting the low screw can set me up so long as the throttle is at full, but in order to run it at idle, I have to screw the low screw back in a full turn.

How can I go about adjusting it? Would I have to bend the tab that connects to the metering diaphragm?

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    Perhaps the carb just needs to be cleaned. If it didn't come with the adjustment, it must not require it for proper function. Permanent changes are permanent. – justinm410 Sep 14 '16 at 15:42
  • Thanks for reply. I have cleaned it as best I can with aerosol carb cleaner. There is a plug on the place where the high-speed screw would be, but I am unable to get it out. – anonymous2 Sep 14 '16 at 15:43
  • The aerosol cans do almost nothing, you have to pull the carb off and soak it unfortunately. In the past, I've found outdated, but new-in-box carbs for like $10 on ebay. That's worth a check too. – justinm410 Sep 14 '16 at 15:52
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    You missed what I was saying. It doesn't have a high speed needle because it doesn't have a high speed jet. It's one jet from what I find in diagrams. Pull it back off and get real carb cleaner soaking solution. – justinm410 Sep 14 '16 at 16:59
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    Take a look here it has a description of the high speed circuit stage. I had used this link a year or so ago when fixing a chain saw carb. Walbro carbs flow They are basically non adjustable for models without a HI screw. – spicetraders Sep 14 '16 at 18:43
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Yes, you can bend the tab

The metering diaphragm enriches the entire range on every circuit. If the fuel level is higher it will require less vacuum under Venturi's Law to pull the fuel from the 'float'.

You can use the metering diaphragm float tab as a method to enrich all of the circuits and then adjust your low speed circuit with the fuel screw to lean out your 'idle' or low speed circuit to create a balanced AFR.

Here is a detailed article on how each circuit functions.

  • YES. Do this if you want it to idle, but run too rich when throttled up. Venturi's Law? Come on, man. This carb doesn't even have a float. – justinm410 Sep 14 '16 at 19:32
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    @justinm410 It has a float mechanism with a needle and seat. Venturi's Law applies with all carburetors. – DucatiKiller Sep 14 '16 at 19:37
  • It's not a float. A float is a float and a diaphragm is a diaphragm. They're an entirely different mechanism. There's an underlying problem that needs to be fixed. Bending tabs is going to richen across the range just messing it up elsewhere. It also may be irreversible. – justinm410 Sep 14 '16 at 19:40
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    That's pretty dramatic. Perhaps you should provide the correct answer. Once the tab is bent, it sounds like from you statements, that the Zombie Invasion will sweep across the planet and we will all die. Post your advice as an answer. Thus far your an art critic more than a resource. – DucatiKiller Sep 14 '16 at 19:48
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    Update: it worked. I bent the tab away from the carb body, adjusted the low-speed, and it worked. – anonymous2 Sep 14 '16 at 20:35
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Perform routine maintenance on your carburetor.

It doesn't have a high speed needle or float.

If the tabs needed to be bent, they would have bent them in the factory.

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    Part of the recommended tuning of the carburetor and all carbs based upon metering diaphragms with a needle and seat is to bend the tab. – DucatiKiller Sep 14 '16 at 19:57
  • @DucatiKiller you're spreading misinformation. You really should reconsider... ya know, or at least look up a diagram of the carb we're talking about. – justinm410 Sep 14 '16 at 20:04

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