Chainsaw Hard to Start & Bogs | Runs Poorly - What To Look For & How to Fix - (Stihl Carburetor)

Diagnosing and Fixing a Chainsaw that is Hard to Start & Bogs Down when running.
In this video I will walk you through the process of Diagnosing and Repairing a chainsaw that is hard to start and when it does get started... bogs down when accelerating.
Initially the saw was just hard to start. After it had run for a while... when you tried to start it again it was almost impossible.
Once the saw got hard to start and began to bog down I was forced to address the problem.
It runs like new now!... and I will show you how I fixed this Stihl Chainsaw so you can repair yours.
This is a very common problem with chainsaws.
You will also learn how to adjust your chainsaw carburetor in this video along with a helpful tip to prevent your chainsaw from having this problem in the future.
*If this video was a help to you give it a "thumbs up". If you have not already done so, please consider subscribing to this channel.
Disclaimer:
Although I have been following these procedures for many years; I assume no liability for any damage that may occur to any person or property as a result of the information provided in this video. I take necessary precautions (that I am aware of) when working on these projects but that in no way implies or creates any expressed or implied warranty or guarantee of any kind of particular result. Any injury, damage or loss of any kind to anyone or their property or anything related to information in this video is the sole responsibility of the user and not Helping U Online (this video).

[@tuberocker69]

Bought a 261 a few weeks ago and made them change the 20" 050 bar that was on it to an 18" 063. Much better, in my opinion!

[@johnclarke6647]

When in doubt, read the Walbro Service Manual for the WT carb. I think that is a MS 250 saw you are working on. The Walbro manual says the preload is 1.0 turns out, as I remember. Setting the preload at 1.5 turns out will make it easier to start but it won’t stay running, because it will go into compressor stahl - to much gas . I don’t use limiters, so I can adjust them where they need to be set to run properly. Even the saws with the big HD carbs run at around one turn out. I just set them all at one turn out and go from there. The last thing I do to a rebuilt carb or a new carb is pressure test them. I want them to hold 5# of pressure to keep the needle from vibrating and putting more fuel into the saw than needed.

[@kevinchamberland]

Thank you very much!!!!! I Repair my MS-250 with your help!!!! I have exacly the same trouble of bogging, I replace the diaphragm with news one from Stihl but my chainsaw would not start...... I dissasembly "again" the carburator but this time, I watch your video and when I fired it up the second time, she start on the way!!!! With your explanations, very easy to set the carburator and now, run like new!!!! Thanks again!!!!

[@helpinguonline]

Way to go…and glad I could help!

[@vlakkieaarde]

Thanks ! Your video helped me sort out my chainsaw....had some fine shavings on the internal mesh screen

[@helpinguonline]

Glad it helped

[@tarzan30809]

Amazing instructions! Just fixed my 250, and adjusted the carburator.

[@helpinguonline]

Glad it helped!

[@earthspirit135]

Great video ! My 250 is now running perfect

[@frankmanibusan8406]

Thank you so much for sharing your experience and a great information on how to adjust the carburetor on a stihl chainsaw thank you so much for sharing you with a great and wonderful DAY peace out 😂 24:05

[@mikeferraro8917]

Excellent demonstration!

[@timfunk5084]

Very good video. I got lucky and was able to add sea foam to gas and it cleaned it. On stihl 290

[@guyschafer2198]

Great video! I have a MS 310 and even though it’s a little newer maybe most of components are very similar and this video was excellent for helping me with the exact same problem and solved it. Really appreciate the tuning part at the end as well!!

[@danalincoln9372]

You made look easy, now I know I can work on the carb👍

[@joeramon8253]

𝕆

[@williamalexpage9288]

Thank you! You helped me fix it with no prior experience!!

[@helpinguonline]

Glad I could help! Good job

[@munsters2]

Good tips. Thank you.

[@misterjameswest]

Great video! Hope I can clean the carburetor myself and put it back together! lol

[@garymanuel4710]

Wow loved this video, really explained great, tks now i know how to find that sweet spot when adjusting carburetor

[@helpinguonline]

Glad it helped

[@blessingfallsfamilyfarm2804]

Really helpful! Got my MS250 starting easy and running smooth again. Thanks!

[@helpinguonline]

Glad it helped!

[@gunterbecker8528]

Whats u opinion on putting a little engine oil in tank n prime it for winter storage which apparently helps keeping the fuel line in good pliable order,apparently last longer and keep one longer out of repairshop ? I'll thank you in advance 😊

[@helpinguonline]

On a 2 cycle engine I do not use engine oil... I use 2 cycle oil. I also push it through the carb with the primer bulb, if there is one, and then drain oil out of tank and press the primer bulb till the oil is out and just air is pushing back into the tank...so there is a coating of 2 cycle oil throughout the carb but not packed in there sitting. This video may help... kzbin.info/www/bejne/poi2nZ-nqrx-iLs

[@Juzzy520]

Oh maaate!! How easy was that!! Thanks👍👍

[@jorgecardona4901]

Great job! Appreciate the detailed explanation

[@helpinguonline]

Glad it was helpful!

[@helmuthoess3737]

Thank you.

[@johnbalasa711]

Thank you good info.

[@helpinguonline]

Glad it was helpful!

[@scumbagg6155]

love the background music

[@AH_1984]

Super help thanks!

[@helpinguonline]

Glad it helped!

[@slimtony1961]

Thank you very helpful

[@helpinguonline]

Glad I could help

[@gunterbecker8528]

Great instructions mate 😂

[@helpinguonline]

Glad it helped

[@duckhunter8387]

Nice! Why must we use the needle valve stops.

[@stephengardner776]

Very nice presentation!!!!!

[@helpinguonline]

Thanks a lot

[@johnclarke6647]

You do not have to remove the handle to remove the carb from the 250. You do have to remove it at an angle but it will come off. Removing the handle parts makes it easier to remove but you do not have to remove the handle parts.

[@frankmchale6916]

That's the very same I was thinking as soon as I saw it!😂

[@luckybhardwaj326]

😊😅😊

[@rickysharp4223]

thank you very much for your help. 🎉

[@helpinguonline]

You're welcome!

[@goshbob]

Excellent Video!

[@helpinguonline]

Thank you! Cheers!

[@gscheirerful]

Hello, First I want to thank you so much for your video’s. They are extremely education and I use them a lot for if nothing else watching your persistence of never giving up. I was hoping to get your advice on something. I actually if you lived close to me (I Live in Alexandria, VA) would bring this over to you so I could learn from you. I have husqvarna 142 e chainsaw. I have changed out 3 carburetor’s on two chainsaws (Sears and Echo) and a leaf blower (echo). On this Husqvarna I have replaced everything except the piston and the plastic parts (i.e. the electrical system, the spark plug, the muffler the fuel line, air filter, inside rubber gasket’s etc.) cleaned the old carburetor and tried it, replaced the carburetor twice with one model, and now with a third model. With every carburetor I have gotten it to start but then it runs for about a 30 seconds at high RPM’s and then turns off. The choke is on sometime and not others times. It has hte 50/1 Tru Fuel. Should I purchase an OEM carburetor for $40. Do you think that is the problem. I have probably spent close to 40 hours trying to fix this chainsaw and just can’t seem lick this. Any suggestions or ideas would be greatly greatly appreicated

[@helpinguonline]

Hard to say without looking at it… Have you checked the spark arrestor to see if it is clogged? It is a screen in your muffler system that can get clogged over time. I assume you have spark and if you do then Most likely you have a fuel problem. Sounds like you have spent a lot of time but the good thing is you are learning a lot as you go and eventually you will figure it out if you persevere and keep searching. Let us know how it turns out

[@notmyname3883]

Chicanic says stop using that factory-made premix garbage fuel. Mix your own. And use 40:1 on that Husky or you'll seize it when you DO get it running!

[@treborterb]

Excellant video...thank you.

[@helpinguonline]

You are welcome!

[@Paul-rx2ov]

Had a old pioneer where it would run good for a little bit when hot then shut off and not start till it got cold .found out that particular model the gas tank was boiling the gas from heat by muffler and coil would shut down from being to hot .

[@michaelboyle4553]

Thanks

[@PkKhakholary-qg5kl]

Very Nice

[@Electronics_123_]

excellent👍

[@helpinguonline]

Thank you! Cheers!

[@johnclarke6647]

I pressure test fuel lines to 7# with my Mighty Vac, too

[@0ptimal]

Mine started acting up, it'd be hard as hell to start, idle for a sec then die, or if it ran it'd bog and die when given gas. I'd messed w the screws over n over. Finally i discovered there was another screw, the idle screw, it was hidden in the black handle, then i followed the turning directions that are on the saw itself and man it runs perfect now. It really is important to have the carb screws adjusted perfectly. I always assumed there was only 2 adjustment screws.. doh.

[@helpinguonline]

Way to go

[@TruggyDriver69]

I have the same issue with my ms391 that’s only a couple years old.

[@joeypartridge8389]

You most definitely can adjust the high side. Hold it full throttle while running and adjust till it run good.

[@rsschdd]

Then back off 1/4 turn so that it is not running too rich.

[@joshlodder8608]

I think he means don't adjust the high beyond the factory stop. That said if you do in fact remove the stop, the factory setting is now changed. I believe he's right in saying you would need a tachometer while making the adjustment. What is considered 'running good' when full throttle and adjusting the high side? Without a tach you could end up setting the saw at too high an RPM while leaning it out which will result in an engine failure.

[@tucker934]

Readers take not that good does not mean all the way hand tight all the way lean youll burn saw up

[@Chollanger148-pv8jp]

You would back off 1/4 so that is not running too LEAN! since lean can damage the bore.

[@steveeaton2967]

​@@joshlodder8608, I think the maximum allowable is about 12,500 rpm. for at least the smaller Stihls.

[@lovestihlquality1369]

Nice video. One thing I can't stand when they put stickers on the plastics. Same on cars. First thing is to remove dealer stickers and license plate frame.

[@johnsolenski140]

Great video! What is the proper adjustment height of the needle pivot arm. I know that it should never need adjustment but would like to check this height during rebuild.

[@helpinguonline]

Place a straight edge across the top of the carburetor body casting and the metering lever should be 3/64 inch to 1/16 of an inch below straight edge on a walbro carburetor

[@carlmaro]

My homelite has the same symptom,, starts, Runs great, won't start when it's Hot.🤷‍♂️ I'll try this next.

[@rubengonzales7739]

My ms 170 will run fine at 1/2 throttle only I’m hoping to successfully clean the carb as u showed after checking fuel line filter and vent line tks

[@nicholashall5028]

My ms 170 keep bugging when i squeez the trigger 😢

[@armadaink]

Great videos, but why not check the fuel filter first?

[@skynjaydensdaddy]

@ 8:26 what you refer to as a reed valve, is the fuel pump

[@andrewfraser7445]

Nice carb video. Thanks

[@helpinguonline]

Thanks for watching!

[@magicone9327]

Tanks under pressure, is the vent plugged?

[@trebledog]

What to do, how to fix. My stihl 025 engine starts, runs poorly, also chain is not consistently spinning or spinning low rpms when sometimes when pulling on the trigger to give it more gas and then tends to bog down. I already replaced carb, plug, fuel air filters, fuel vent, compression seems ok, using new premix 50:1. So I think I need to tune carb to find the "sweet spot". Is that the right way to go? Help.

[@herrent]

Is this the same carb set up as ms291 stihl

[@gunterbecker8528]

Sir, running a 251c stihl saw fairly new. Every time i use it black residues appear on muffler! Dealers here in Australia aren't very helpful! Im running 98 octane and sthil HP OIL,wonder if it could be the oil ? Please advise, i thank you in advance Gunter

[@daultonruff2281]

Went through all this before I finally gave up and took it into a shop. I got it back, (shouldn't have done this) let it set for two months. Tree fell on my fence so I tried to start it and it's doing the same thing it was before-nothing. I did all the suggestions here. I think I need a different saw that is more resilient, not so fragile and temperamental. The thing is practically new. For sale -POS-

[@nickwhite6717]

Don't blame the saw. Look after your gear and it'll look after you. Either use stabiliser or ethanol free fuel. If storing for a decent period, run them for a couple minutes once a month or so

[@mikezupancic2182]

Start watching actual repair videos. Your gas was probably crap. #1 reason 2 cycles run for crap or don't run.

[@Tailspin80]

It’s a Zama carb. On the official video they make a big point of NOT shooting carb cleaner or compressed air into any of the holes in case it damages the check valves. Having said that my Zama still worked ok after I did exactly that! kzbin.info/www/bejne/gHylmHt-mpZlitE

[@msmith8401]

What is the recommended turns for the LA (idle speed screw) from the factory? I see the specs for the L and H screws but no one mentions where to start with the LA screw

[@helpinguonline]

Many saws idle setting are around 2800 RPMs but you would have to have a tachometer to check and set that. Most people set the saw idol high enough so that the chain is not turning at idle With the brake off. So… With the break off Turn the idle screw clockwise so that the chain just starts turning and back it off from there so that the chain stops moving at idle.

[@sultankudarat1777]

How to adjust caburator sthil ms 650

[@johnclarke6647]

For what it is - the MS250 is a bitch to crank. Mine likes to yank my arm off and lift my right foot off the ground. The best way to crank it is to pull the starter rope, slowly,past the first compression hump and then, yank like hell. Otherwise, hold on if you can.

[@mikehampton848]

Well said sir. I heard your voice as i read your comment,, mine is the same way 😂

[@johnclarke6647]

@@mikehampton848 my 025 is a piece of cake to start. I put an 18”L4 lightweight bar, .325 bar on it yesterday and cranked it up to see how this new bar oiled. It oiled fine and I even restarted it on my leg. It ran a slight bit rich in 93 degree weather but that was it. I did not lean it out, any because it will be hot, here, all summer and should be fine in cold weather. Had I been cutting with it I may have leaned it out a tad. The 025 is almost an exact copy of the 250 and I do not understand why the 250 is so hard to pull over. My best method is to short pull it several times in full choke and then pull it past the first compression and then yank like hell. After a few pulls like this you should be able to pull it normally. I like my 024 and ms 260 a lot better. They have deco valves on them. They start up without beating me to death. You cannot put a deco valve on the 250 - wish you could, I would.

[@user-ix2mz7mp9y]

Agreed, the 250 has a lot of compression and is a "bitch" to crank but runs like a scalded dog once running....😊

[@rudysaldivar4228]

Aren’t you supposed to start it with the brake on so it doesn’t over rev with the partial choke on?

[@damian9504]

I have stihl ms170 and have only one screw and I don't know how to adjust the carburetor

[@paultyrer2171]

Nice to see someone not wearing gloves

[@jamesahr2634]

Jjust pull trigger carb rod pops right out no need remove haandle

[@larryreno8293]

I see that’s you first time disassembling that saw🧐🧐

[@hei_________katdalunga4854]

2:25 bro what is the size of this socket wrench?

[@larryreno8293]

It’s a 8mm or 5/16 will work

[@MikeJones-rk1un]

How about just adjusting the carb ? Is that too simple?

[@steveeaton2967]

Incidentally, not starting when hot often means a bad coil instead of any fuel problem!

[@patrickwilson5847]

Lol just pull the trigger a lil'bit, and pop the linkage off, if ya take those saws apart too often they fall apart,

[@martincrean7993]

How could not getting enough fuel cause it to such two much air....isn't the air intake governed by the size of the bore in the carburetor and the position of the throttle flap ?..Am I wrong...I'm confused now...

[@ArrowItArchery]

Air to fuel ratio. There's more air intake when it's starving for fuel, and then there's excessive fuel intake (flooding) when it's asking for more air. You have to gain the right balance for the proper combustion.

[@sultankudarat1777]

O grading info

[@singleshot1331]

028 is a lot easier to get the carburetor off

[@smartt]

I got 5 seconds in and it sounded like ignition coil.

[@Roadking556]

Yeah and next year it won't start again!

[@bertgrau3934]

What you need to do is when your finished and want to store it for a while, use 2 stroke oil, or automatic transmission fluid, use the primer bulb to pump the oil/fluid through the carburetor. That will keep the diaphragm/fuel pump from drying out. It will smoke when you start it, but much less problems If it doesn't have a primer bulb, you will need to choke it until the oil/fluid gets to the carburetor

[@justinsane7128]

I won't state the obvious since I'm a husky snob. Gas always the bad gas.... I'm trying to buy nonethanol and stabil it.

[@helpinguonline]

Good idea to use the ethanol free gas...but it is still a good idea to drain the gas and run it out of the carb if you will not be using it because the gas and oil mix can also separate a bit and gum up the carb.

[@patrickwilson5847]

Yea you can just take the 8mm nuts off, linkage and fuel line,

[@mikecopenhaver4484]

Only real fix is to put a Walbro carb on it!

[@hyfy-tr2jy]

dude....let the unit warm up before you go full throttle

[@Boobtube.]

if you don't leave gas in it for months on end, this problem will be non existing.

[@donmoore7785]

Debris getting into the carb is unrelated to sitting and being used. That can cause issues that require the same procedures to address.

[@carlodonnell146]

It didn't sound at all, totally dead.

[@richardplane2155]

Endless videos , all the same , all about the same problem and, wait for it, all about the same make. Can i make a polite suggestion ? . How about Stihl make a Fing chain saw that actually Fing works ? Would that be too much to ask ? Ive got four Stihl machines all the same problem. I'm never buying another one . You're supposed to be a premium German brand. Get your act together.

[@mikehampton848]

I will gladley take those pieces of junk off your hands,, sounds like youd be better off wuth a dewalt cordless or something of the like,, or maybee a huskey ,, ya the one with the external clutch so you cant take the bar off if your in a pinch sititution😅 anny way. Good day

[@erdemir5641]

Lol why are you using a chainsaw in your bedroom