Carburetor Tuning - 10 Things You NEED To Know!

When your engine isn't running correctly, it's likely the carburetor that needs adjustment. You'll find these carburetors on Honda, Stihl, Husqvarna and other well known garden power equipment and adjusting them can be daunting. This in-depth tutorial will cover all of the symptoms that can occur with your small engine and how to adjust the carburetor to correct the fault. #Honda #carburetor #husqvarnacarburetor #smallenginerepair carburetorservice,
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Any links to products are likely to affiliate links and I may earn a small commission from qualifying purchases with no additional costs to you. Thank you!
0:00 Introduction
0:01 Difficult to start engine.
0:42 Engine bogs on acceleration.
1:29 Engine splutters on acceleration
2:06 Low power at full throttle
2:47 Engine running rough with excessive smoke when at full throttle
3:22 Engine idles too fast and idle adjustment is unresponsive
4:05 Difficult to start engine with fuel out of the muffler.
4:24 Engine RPM drops excessively after full throttle or dies completely
5:01 Engine stalls when left idling for a short period of time
5:53 Engine RPM's change when you turn your engine on the side
7:50 Which screw do you adjust first?!

[@VintageEngineRepairs]

If this video helped you, please consider clicking on the THANKS button above to support my channel 🙌

[@Syncop8rNZ]

This one's a keeper - it's going straight to the Pool Room.

[@VintageEngineRepairs]

Hi awesome :)

[@justinanderson9280]

I was only googling to find this info last week mate. Thanks for the cool tutorial, well done 👍🏻

[@VintageEngineRepairs]

Pleased it helped!!

[@GeorgeFrost70]

Fantastic tutorial - Thanks!!

[@VintageEngineRepairs]

You’re welcome, thank you :)

[@dallaskaraokecab]

Thanks for the video, the best I've seen so far.

[@VintageEngineRepairs]

Thank you!

[@timc3600]

Really useful, thanks.

[@VintageEngineRepairs]

You’re welcome!

[@Paul0000ification]

Great reference video 👍

[@VintageEngineRepairs]

Thanks!

[@jimmurphy5739]

Excellent explanation. Thx!

[@VintageEngineRepairs]

You’re welcome :)

[@almclean4835]

Very informative video Tom.

[@VintageEngineRepairs]

Thanks Al :)

[@olivermair9692]

Fantastic, thank you very much!

[@VintageEngineRepairs]

You’re welcome! :)

[@heterogeneityrocks1]

As always i enjoyed the video. Cheers

[@VintageEngineRepairs]

Thank you!

[@khndenmark]

You are the best. Very very good and informativ video, Thanks 😊

[@VintageEngineRepairs]

Thank you!

[@RussellHoughton]

This is some great info. I'll have to Wright it down for my cheet sheets.

[@VintageEngineRepairs]

Great! Glad you enjoyed it

[@SmokeyAlex]

Thank you!!!

[@VintageEngineRepairs]

You’re welcome!!

[@imanolberecibar]

Another cause i have found for an engine to stall after coming off throttle is a metering lever set too high, even with the proper mixture screw setting if the lever is set above where it should it will cause the engine to suck a lot of fuel when the throttle is released and make it slow down or even stall

[@imanolberecibar]

Also, that information about the independent or dependent carburetor mixture screws is really cool, never stopped to think about it but it makes perfect sense

[@dinismaia]

Precious information 😃 thanks 🙏👍 5 🌟

[@VintageEngineRepairs]

You’re welcome :)

[@Robsenginerepairs]

Nice info bud 👍

[@VintageEngineRepairs]

Thanks for watching mate !

[@BensWorkshop]

Useful information.

[@VintageEngineRepairs]

Thanks Ben 👍

[@metheewatchakittikorn4796]

Thank you so much.

[@VintageEngineRepairs]

You’re welcome!

[@ronniebarker79]

top draw info m8 could learn alot of you buddy

[@VintageEngineRepairs]

Thanks Ronnie mate I really appreciate the kind words. Glad you enjoyed the video!

[@thomaswhitty3742]

Very useful Information Thomas Ireland

[@VintageEngineRepairs]

Thanks!

[@KensSmallEngineRepair]

Dependent carb, adjust the high speed circuit first. Wish I knew this 2 years ago! Thanks Mate!!

[@VintageEngineRepairs]

Pleasure Kenny!!

[@billsanchezpineda6211]

Hi, how to adjust an dependent carb? Thanks to You I dominate the low jet. 🇵🇦🤟

[@VintageEngineRepairs]

Video coming soon :)

[@GuysPlayingWithTools]

Good video Tom🙂

[@VintageEngineRepairs]

Thanks Bill mate :)

[@Big_Johns]

Very informative video Tom. I give it 3 shrimps on the barby. 🙂👍

[@VintageEngineRepairs]

Hahah love it 😂 thanks John mate :)

[@Big_Johns]

LoL, anytime brother 🙂

[@Big_Johns]

🤣 Sorry Mr Henry, I could only afford 3 shrimps.

[@VintageEngineRepairs]

@@Big_Johns I’ll take the bucket of old Filters and diaphragms 😂🤣

[@Big_Johns]

LoL Tom!!! 🤣

[@Syncop8rNZ]

Hmmm I recently acquired a Mac 10-10 and it seems to suffer from Symptom 6: Engine idles too fast and idle adjustment is unresponsive. When I start it it's racing. I backed the idle screw out and it eventually slowed a little but then at some point sped up again.

[@MyGreenLawn2019]

Just subscribed dude. I thought I was already sub’d sorry about that. I’m in now lol

[@VintageEngineRepairs]

Haha all good :)

[@Syncop8rNZ]

0:00 1. Difficult to start engine. 0:42 2. Engine bogs on acceleration. 1:30 3. Engine splutters on acceleration. 2:06 4. Low power at full throttle. 2:47 5. Engine running rough with excessive smoke when at full throttle. 3:22 6. Engine idles too fast and idle adjustment is unresponsive. 4:04 7. Difficult to start engine with fuel out of the muffler. 4:23 8. Engine RPM drops excessively after full throttle or dies completely. 5:00 9. Engine stalls when left idling for a short period of time. 5:52 10. Engine RPMs change when you turn your engine on the side. 7:49 BONUS TIP! Which screw do we adjust first?!

[@VintageEngineRepairs]

Wow thanks! Pinned this comment to the top :)

[@Syncop8rNZ]

@@VintageEngineRepairs Cheers. I was still editing it, tweaking the times but can't anymore, I guess because it's pinned now?

[@VintageEngineRepairs]

@@Syncop8rNZ oh no, I’ll unpin it, let you do what you need and then re pin it.

[@Syncop8rNZ]

@@VintageEngineRepairs Oh I missed this, went to the pub. ;-) It's all good, some of the time stamps could have been a second or two later but close enough. My OCD is mostly satisfied.

[@MrMad1966sChannel]

Great vids.. Got symptom 2 on my MS362 you say "lean symtom on idle" however upon removing the shroud no visible L H screws so i am assuming mtronic model.. Does that mean an electronic carb and could anything be done ??

[@VintageEngineRepairs]

Yes it is electronic in that case, no fuel adjustments possible sadly! Remind me what symptom 2 was (been a while since I watched the video) and I may be able to help.

[@sameertsm]

Very informative, thanks a lot, by the way, the other carb, not the walbro type, what is that one called?

[@VintageEngineRepairs]

Thank you! It’s called either a “rotary” or a “barrel” type carb :) The thing I like most is you can run them on the edge of lean at idle for excellent trigger response and they don’t lean bog like the more common butterfly type.

[@sameertsm]

@@VintageEngineRepairs Thanks a lot for the quick response :) Am an RC modelller and your videos are really helpful in understanding these carbs, tuning them and troubleshooting. Subscribed :)

[@normanziegelmeyer7693]

Are the springs under the metering valve different for different carburetors? While attempting to overhaul carburetor on ryobi leaf blower RY-09440 I lost the spring. Trying to find a replacement . Thanks

[@VintageEngineRepairs]

They do vary, but honestly I have interchanged them without any problem whatsoever.

[@TgWags69]

So the low speed screw is like the drone on a set of bagpipes.

[@VintageEngineRepairs]

No idea as I don’t play bagpipes

[@brownp93]

I have an independent carburetor that works in the middle and not WOT. It operates well except in the mid throttle range where it will slowly lose rpm at a constant throttle position. I will open it up a little more by the throttle to which it will surge to higher rpm. What is a good mid range fix? (modifications are possible if suggested) it is the walbro 32

[@VintageEngineRepairs]

These don’t have a dedicated mid range circuit. Open the H screw 1/4 turn :)

[@brownp93]

ok thanks and lets say I'd like to add a dedicated mid range circuit, any advice where to look for reference or your thoughts?@@VintageEngineRepairs

[@iotioimping]

Hi Tom , I just rebuild a chainsaw changed gaskets ,sealings, new piston but when I accelerate it wants to die . If I accelerate gradually it gets eventually full throttle with no problem , could be the main nozzle in the carburetor. I checked the carburetor with hand pump but could not check the main one , the little drillings are ok , checked them with wd40 .I didn't want to take it out but could that be the problem . From t , l ,h screws the problem could not be resolved so I think the main nozzle is bad .

[@VintageEngineRepairs]

Hey! It sounds like a fuel starvation issue to me. Did you do a pressure and vacuum test on the saw? That’s the #1 most important test to do on ANY 2 stroke. Once you’ve done that. I’d say start from the fuel filter and work your way to the carb checking if it holds pressure and vacuum. You need a tool like this Mityvac Pressure & Vacuum Tester - amzn.to/3vysI3V. You can get cheaper ones, just make sure it does pressure and vacuum :)

[@iotioimping]

I did that too because as you said in one video to check if the work is done good (forgot to mention). the filter I did not changed although.

[@mooregoodink7734]

Thank you. My Echo PB265 starts well and revs well but after ten minutes of running it begins to lose power and, although just my conjecture, it seems to run hotter than previously. Might you have any suggestions to resolve this?

[@VintageEngineRepairs]

Hmmm, you could try opening the H screw 1/8 of a turn and see if that helps?

[@mooregoodink7734]

​@@VintageEngineRepairs Thank you for taking the time to help on this matter. I haven't altered the high-speed adjuster screw so far because this blower has run flawlessly for almost a decade and, as implied above; it still performs beautifully with the H screw still concealed beyond the plastic plug--that is, until it gets warm or perhaps closer to hot. During those first ten-to-fifteen minutes, it responds immediately to throttle movement, neither bogging nor burbling. I did remove the muffler and although the port appears normal (no heavy deposits of carbon) the spark arrestor is destroyed. I wondered if the main body of baffling behind the arrestor gets so hot, perhaps red hot, that a new spark arrestor screen might resolve the conundrum. Yet, if you still consider that high-speed adjustment (enrichment) remains the best option, I'll try it. Thank you again.

[@mooregoodink7734]

Coil failure was responsible for the Echo blower engine stopping ten minutes after starting. The difficulty was unlikely to be caused by the carburetor because I had access to another that produced the same result when warm. The fascinating thing was that though the spare carburetor had a larger diameter venturi, it worked amazingly well, at least for the first ten minutes. Thank you again for your wonderful series of instructional videos.

[@carlodonnell146]

I am concerned though that closing the high-speed screw with the engine running may damage the engine, but cutting off the oil.

[@VintageEngineRepairs]

You don’t have to be, it’s literally just a second before it dies and there is a lot of residual oil to keep it safe. Just like running out of fuel, the engine cuts out and you refill the tank, thanks for watching!

[@carlodonnell146]

fair enough!!@@VintageEngineRepairs

[@TheNuflyer]

What if during idle, the RPM goes up and down?

[@VintageEngineRepairs]

That’s often caused by an air leak. I’d suggest pressure and vacuum testing the engine :)

[@TheTrailblazer1974]

What does 4 stroking mean?

[@VintageEngineRepairs]

It’s when a 2 stroke engine fires every 4 strokes rather than 2 due to an overly rich condition and ineffective scavenging of the charge!

[@rhm504]

Thank you so much.

[@VintageEngineRepairs]

You’re very welcome :)