HELP! Walbro WT-743

[Redhorse]

The adjustment screw for the high jet is just spinning and is loose(will wiggle around) on my carburetor. It is from a stihl MS260 and originally had the red liter cap. I ended up destroying the red cap when I did my muffler mod. I am worried that the high screw has broken and don’t know if I can get it out or if the carburetor can be disassembled enough to remove it.
Or am I better off getting a whole new carburetor that doesn’t have the limiter caps because I have modded the muffler and need more fuel at wot. Any help greatly appreciated.
Thank you

 

[hacskaroly]

The adjustment screw for the high jet is just spinning and is loose(will wiggle around) on my carburetor.

Are the threads on the screw possibly damaged allowing it to spin but not bite or is the screw itself partially broken off? If it is free spinning then I would guess that either the threads on the screw or the socket (or both) are damaged and likely will end up being an air-leak issue.

 

[Redhorse]

I got what was left of the red limited cap out but the head and maybe part of the screw went flying. This is what is left in the location of the high screw.

 

[EFSM]

I got what was left of the red limited cap out but the head and maybe part of the screw went flying. This is what is left in the location of the high screw.View attachment 476994

My diagnosis—that screw is screwed.

 

[Sloughfoot]

Might be best the screw is busted instead of the threads being wollered out.
BTW, how did it get broken?

 

[Redhorse]

Might be best the screw is busted instead of the threads being wollered out.
BTW, how did it get broken?

Short answer years of abuse.

When I did the first muffler mod I had read the limiter tab could be removed with a drywall screw. I didn’t take the carb out of the saw when attempting that so it just broke and I tried digging out what I could of the cap and got it where I could turn up the fuel. Looking back in that process I bent the screw slightly. When adjusting over the years the screw driver handle was going in a circle. It also would go out of tune frequently. I had put a new muffler on it this fall and readjusted tune but I would end up with the screwdriver beside the screw head instead of in the slot and I could only tell after I tried turning and it would turn. I didn’t ever feel it break, I haven’t been able to keep the saw running at an idle this fall and have been adjusting the tune a lot. Then Monday when I tried closing it and reopening to factory it just spun and here I am. Replacement at my stihl dealer is $80 and it is in stock

 

[Sloughfoot]

$80 is a great price for new OEM. Professionally cleaned and kitted carbs sell for $40 or more.

 

[Redhorse]

$80 is a great price for new OEM. Professionally cleaned and kitted carbs sell for $40 or more.

Can I swap one of the other models that came out on this saw? Will it fit in correctly?

 

[hacskaroly]

Can I swap one of the other models that came out on this saw? Will it fit in correctly?

Looks like you have the option (according to the IPL) of the WT-426, 427, 581 and 590. I am not sure what the differences are between them, but they all appear to have the same form factor and should mate up like one you have.

 

[dangerousatom]

Maybe.......maybe after you get a replacement carb try and clean out the hole and screw top extremely well with denatured Alcohol. Then find a long screw that is slightly smaller then the hole and put a dab of JB weld of other thick quick set epoxy on the very tip of the screw. Put it in the hole and pray while you wait for it to set up. If the small engine gods hear you it will bond to the busted screw and u will be able to turn both out.

Good Luck!

If it were me I think Id go in with a carbide dental burr on a rotary tool and ruff the broken screw top up before epoxying as well.

 

[Sloughfoot]

Looks like you have the option (according to the IPL) of the WT-426, 427, 581 and 590. I am not sure what the differences are between them, but they all appear to have the same form factor and should mate up like one you have.

Maybe only have to switch out the throttle and/or choke assemblies?