Stihl 024 carburetor tuning

[Good ole’ boy]

I have a Stihl 024 that I’m working on, and I’m scratching my head on tuning it. The carburetor has a new rebuild kit, and I believe the metering lever is the correct height. The initial settings are one turn out on low and high, but it wants to run at 3/4 turn out on the low side. When I turn the needle in, all the way seated, it won’t kill the saw. My question is, what is causing the saw to be so rich on the low side that you can’t lean it out enough to kill it? I tried with the air filter on and off, but it didn’t seem to matter. This issue is something I’ve never run into before on other saws. If it matters, the carburetor is a Walbro WT series.

 

[stihltech]

Leaking welch plugs, inlet needle too high, wrong metering diaphragm, (center pin too long), lever binding on shaft, high speed jet (usually causes a lean on low side), incorrect gasket kit, bad diaphragms (even with a new kit). And yes, pressure and vacuum test. Once in a blue moon it makes it run rich. Don't ask me how. I should not happen, but it does.

 

[Gord404]

I just pressure test them- should hold 15 lbs forever and make sure you put gasket on first and diapham second, if it won't hold pressure could be the metering valve leaking or diaphram button putting pressure on it and arm needs to be adjusted in-imo

 

[Good ole’ boy]

Thanks, I need to buy a pressure tester. Any recommendations on a pressure tester? I’m always trying to learn what can cause these issues, so this is valuable info.

 

[2StrokeFondler]

Thanks, I need to buy a pressure tester. Any recommendations on a pressure tester? I’m always trying to learn what can cause these issues, so this is valuable info.

I'm happy with my noname Chinese model for 20 bucks. Thing is simple enough - and not used enough - to not go MightyVacc for my use case.

 

[Good ole’ boy]

I'm happy with my noname Chinese model for 20 bucks. Thing is simple enough - and not used enough - to not go MightyVacc for my use case.

I ordered a pressure/vac. I’m curious to see how the carb tests.

 

[Gord404]

I use the mitivac all metal mitivac 8500 because I use it almost everyday- a leaking seal on a crankcase might not show up on pressure but show up on vac, plus a brake bleeding kit comes with them too, a lot of uses, they are about 100$ for the kit. but in your case the cheaper one will probably be fine

 

[Good ole’ boy]

I use the mitivac all metal mitivac 8500 because I use it almost everyday- a leaking seal on a crankcase might not show up on pressure but show up on vac, plus a brake bleeding kit comes with them too, a lot of uses, they are about 100$ for the kit. but in your case the cheaper one will probably be fine

That’s good to know. That’s the kit that I ordered.

 

[Titan191]

Hello, I'm rebuilding Stihl 024 AVS which has the same symptoms as the OP has - shuts off at idle and runs rich no matter the adjustment - but the carburetor is a Tillotson HU-54. So far I installed new intake boot, new fuel line with filter and new impulse line. Got an original Tillotson rebuild kit and changed out the diaphragms, needle with lever and cleaned it. Cannot adjust it to run properly if my life depended on it - it dies at idle and spark plug is covered with fuel. Did a pressure&vacuum test on the crank case and it is ok. Also pressure tested the carburetor and it holds 0,5 bar/8 PSI without issue. Anyone had this issue or is the best option to replace the carburetor? Can I replace Tillotson carburetor with Walbro?

 

[2StrokeFondler]

Did you make sure the lever is the right height? Can you swap the old one in and see if that helps?

 

[Titan191]

I checked the lever height when installed and also I compared them side by side and they appeared the same. I also measured the diaphragm "nipple" and it was actually just a hair shorter than the original.