Small Engine Repair: Cleaning Carbon Buildup on the Exhaust Port & Muffler on a 2 Stroke Engine

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*Always follow the instructions in your repair manual when doing repair or maintenance work on Outdoor Power Equipment. Manuals can be found at the manufacturers website.*
Small engines used in outdoor power equipment often suffer from carbon build up in the cylinder head, exhaust port and muffler. The is more common in 2 stroke engines than 4, but it does occur in both. In this video I inspect the exhaust port and muffler on a Echo SRM-230 trimmer. The muffler was very clean, but the exhaust port had carbon build up that blocked half the port. To clean the port, rotate the engine until the piston skirt is covering the exhaust port, and take a screw driver and lightly scrape the port to remove the carbon. Than take compressed air and blow out the port to remove the carbon pieces. Mufflers on small engines are usually sealed units, so cleaning them is very difficult if not impossible. Its easy and less expensive to replace a sealed muffler with a new one. Some mufflers have screens, which can be cleaned with a wire brush and compressed air.
This trimmer was run by the previous owner without a trimmer line knife attached to the deflector. This allows the trimmer line to extend beyond the manufacturers recommended length, and this causes a excessive load on the engine. I believe this is primary responsible for the carbon build up on the port.

[@maxim9939]

Never knew people can be so smart at fixing products good job

[@kings17court]

I appreciate guys like you, who could teach guys like me, how to fix things. I'm not mechanically inclined, but a useful video like this comes in really handy. Thanks for taking the time to share.

[@shawndubay4050]

Hi there. Very good job getting the carbon out of the port. I normally put the engine on its side with the exhaust port up. Muffler off of coarse and put a little gas and let it soak. After a bit I take a thin wooden dowl rod with a slightly sharp tip and the carbon comes out easily. A softer wood dowl is alot easier and safer on the piston. If you accidentally slip and hit the piston it won't damage it. As far as your Muffler that round thing inside is a catalytic converter. Your trimmer needs high rpms to heat it up and it will actually burn residual oil to nothing. I mean not even smoke. It is important to run the right oil to gas ratio like 50 to 1 or 40 to 1. If you have two cycle equipment without catalytic converters a propane torch is your best friend. I take the mufflers of, heat them till the whole muffler is glowing orange, let cool, blow it out with compressed air, put it back on and they absolutely scream at full throttle. I have a Bernzomatic mapp/pro turbo torch for the muffler cleaner. Just in case you want a great torch too for doing that same thing.

[@howardparis2409]

Thank you very much . A friend gave me two Ryobi ss30' s and said won't run .you can have them.I spent 2 weeks working on the carbs then watched your video . Both are fixed now 'in one afternoon!!!

[@diselvisdontsing]

Great Video! I have an inexpensive Poulan Pro 33cc Trimmer with the attachment feature. I was going crazy as to why after replacing the spark plug and fuel filter and new fuel with correct 40/1 mixture I had no power when holding down throttle. Found the carbon deposits and cleaned, and back to normal! I was seriously contemplating buying a new machine! Thanks A Lot!

[@smallengineshop]

Elvis Romero Good to hear! Thanks for watching!

[@Sensei948]

@@smallengineshop 33:1 oil mix is good ?

[@timelordlarry1962]

Thank you for doing this! I bought an Echo trimmer about four months ago I was wondering exactly how to do this. Now I know! :)

[@DOLRED]

Was reading the manual for my old MTD single stage snowblower and saw a comment on cleaning the muffler and cylinder exhaust... I searched the subject and ended up here. I was out doing snow yesterday and the muffler fell off!!! The bolts loosened up I guess. I was lucky to locate the missing one on the ground where I started as I thought it might have been thrown into the snow by the exhaust chute. Mufflers are expensive!!!! The one for mine is $40. We only paid about $150 for the entire machine. Luckily I will reinstall the muffler. Thanks for the video!!

[@kyfw6351]

DOLRED LOL!! Sorry for your misfortune and glad you were able to put it back on but that made me laugh :-)

[@AnthemBassMan]

Yeah, those fins you see inside the muffler is the catalytic converter. My Echo CS370 chainsaw has the same setup. Except I did the muffler mod and drill the cat out then readjusted the carb screws to get it running even better. It’s a little screamer now. I also mow with 44 and 46 year old Lawn Boys. Their service manual suggests using a 3/8” hardwood dowel rod to clean the ports to minimize the chances of scoring the piston. Good video!

[@scottjohnson9683]

Thanks for this video...solved my slow speed problem! Most of the build up was in the spark arrestor body. Runs like new.

[@bobbeyette3227]

Thanks for your time making this video, good presentation, sure it's helpful to a lot of people out there. Big thumbs up

[@tonym6920]

Nice job! Like they say, an ounce of prevention is worth a pound of cure, lol. Thanks for the vid.

[@TheCribbp]

Great Video thanks. I've just repaired my Stihl FS-55 after watching this. Muffler slightly blocked, but driveshaft had a load of string wrapped round it, so was losing power. Running better than ever now. Thanks again.

[@mattmag3089]

this is such a common problem on commercially used 2-stroke equipment. i clean the exhaust ports of our redmax blowers and whips every year... LISTEN TO THS GUY! even a small blockage will affect performance. this is the first thing i check when a 2-stroke "doesn't quite run right" or takes a long time to warm up. you'd be surprised how clogged up they can get, and still run!

[@madhavanravikumar3329]

From India....nice video dedicated explanation... Any idea how to reduce noise level in a two stroke strimmer....

[@rauljuarez3884]

You can't .. From California..😎

[@karlrovey]

You don't. I'm guessing there are plenty of exhaust clogs caused by people running at half-throttle to keep the noise down. My leaf blower manual actually says to run at full throttle for at least five minutes per hour of engine run time.

[@karlrovey]

You don't.

[@LeonMTan]

Gonna do it to my stihl trimmer,it feel only 1/2 power now after 3 years.

[@Krankie_V]

When I have a plugged up muffler I soak it in kerosene then torch it. It usually burns the majority of the carbon buildup out leaving it fairly clean. Another way is to toss it in a wood stove till it's red hot then blow compressed air through it. I have never seen an exhaust port so clogged up like that!

[@brianeastman3547]

Keep up the good work man

[@waynetemplar8026]

To reduce carbon build-up I used to polish the exhaust port (and squish band on the cylinder head) on my two-stroke motors to a mirror finish using metal polish. Just remember not to polish the inlet ports - these need to be slightly roughened to produce turbulence to allow for good fuel/air mixing.

[@jdsniperhed9722]

Wayne Templar o

[@PeaceflSoundz]

How do l install a primer on my gas saw no power stroke engine

[@walterpalmer2749]

Might cleaning the carbon build up at the exhaust be better with a shaped, shaved wood piece (Shish-kabob-like perhaps) so not to score against the piston or metal? Thanks for sharing. Have an old Echo. Now hard to start and keep started. Use to be a gem to run and will now tackle , thanks to your video, the exhaust part after fixing the bulb primer leak. Oh- turning the cylinder is a great tip.

[@job38four10]

I'm surprised high temp never seize wasn't used on those muffler screws.

[@philliphall5198]

Thank you for information and advice Don’t lug the engines

[@MrGrummpy]

Wow? Who cleans the carpet in your shop? I'm impressed. That is your shop, right?

[@kauaiphotography]

Aloha! Always enjoy your vids, especially the ones dealing with weed whackers and lawn mowers. Don't know if someone already mentioned this, but the spark arrestor screen seems to be missing? I have a Echo SRM-210i and the exhaust is exactly the same. My apologies if it was already mentioned in the earlier comments, but I didn't see any annotations in the video. Warm regards!

[@theextremeshop1886]

an easy way to clean the muffler is to use a propane torch it works relly well on screens to

[@0truckmafk]

I love the Napolian Dinamite format!!!!!!!! SUBSCRIBED!!!!!!!!!!!!

[@1cleandude]

Echo SRM 265T: awesome pure power!! I love mine.

[@philliphall5198]

Some times I’m shocked at how much carb can be in them and still half ass run, I hang them up above my head with safety glasses and scrape it out Works good and then blow air and flush with B12😊

Gotta do this tomorrow.. Needed a weed eater and someone threw one out lmao. Got it to start but it wouldn't warm up and has been sitting for a good long time. Ive done this before and it worked on the old feather lite I found in the trash. I'm cheap haha and I know never to BUY a feather lite. They are like disposable lighters! Thanks for the video! :)

[@smallengineshop]

***** Briggs low end engines are designed to last close to 2000 hours under ideal conditions, but most people replace their Briggs mowers with less than 200 hours. Thanks for watching!

***** Had a Briggs & Stratton engine on a mower last me like 8 years. Was mowing yards every summer with it. They just don't make things like they used too because the majority here in America has gone a little dark age in the mind. Gullible country is a place for business men to become lords.. :(

[@deniseleyba5933]

+Wild*light yry there

[@TurboDoggo]

I usually start the motor before I reinstall the exhaust pipe because it sounds cool. :)

[@smallengineshop]

Avery Fugett Thanks for watching!

[@otisrush8110]

when you do that you're running it lean which damages the engine.

[@howardparis2409]

When I took the mufflers off I soaked everything in purple power then water to wash the PP off then blew them off with air and scraped the rest off.

[@SuperJrjames]

I have a muffler bolt snapped off in one of these Sthil what size heli coil would I need to repair the hole Have you had any success with this method John

[@marcusmcclelland6777]

I normally burn the carbon with a torch, make the screen glow and then blow the filter with compressed air to remove the carbon. Try that it works well for me mate it might work well, the ones ive worked on tho have a removable plug. Some band new blowers run that rich from new they block up so fast.

[@freddiejohnson1013]

Yes i want to know where you bought that tool from i like that one also good job on that echo weed trimming i have about three of four of them only i think im gonna use most of them for parts

[@ayyye9459]

Ok so i done watched every video there is on this filter that everyone has on the muffler... Well my craftsman doesn't have anything like that on the muffler so does my weed eater have a screen i can clean or all i gotta worry about is just the inside of the muffler

[@mc2whls]

A Wooden Dowel cut on an angle is safer for removing carbon from the exhaust port. Much less chance of damaging the piston.

[@philliphall5198]

Has anyone tried oven cleaner??? I heard it works great and cleans muffler to

[@jheurtin1120]

Wire brush is a safer option for cleaning the port

[@signalhillscooter]

You want to polish the ex. port so the carbon doesn't want to stick so readily, and port match the port to the exhaust gasket and muffler can.

[@outdoorsman310]

will those cats get cleaned if you clean them in gas and then set it on fire?

[@brodierutherford]

Nice video, I have a echo srm 210 and i tryed to clean the carb out yesterday and when i started it and it was puttering and i had to play with the choke and use the choke to let it run but it ran for like 5 seconds then died, I really need to figure this thing out cause I cut crass for a living so its a necessity. i tryed to clean the fuel filter. and removed it then started it but still had to adjust the choke it get it to run for a couple of seconds. gonna try to clean the carbon maybe that will do it. any advice thanks. Brodie

[@firstmkb]

Good content, but worth reshooting with better camera and light so we can see details.

[@Willy12927]

After loosening the carbon, I prefer to use a shop vac to suck out the loosened carbon, rather than using compressed air.

[@Maximvs316]

Great video, thanx for posting. Question: I have performed a carburetor clean up on an older Shindaiwa blower and got it running reasonably smooth at this point. However it seems to be blowing fuel (50:1) out of the breather intake. Any ideas why this might be happening? Thanx in advance.

[@Jim-ie6uf]

Maximus Dove plugged exhaust

[@shoprat17]

To clean them mufflers what works real well is to heat the inside up with a torch until the carbon ignites and let it burn til it goes out.

[@bagyanagar_wasi]

Thanks for the very detailed diy video

[@zillemowla]

Can you please upload a video on how clean the gasoline engine bicycle Carburetor regularly after use.

[@michaelwindsurfer54]

i think you should take the cylinder apart to clean the top of the piston too,not just the exhaust port,the piston usually builds up carbon too

[@fidelcatsro6948]

I do this often on my 2stroke bike . I didnt know this trick few yrs ago and I blew my engine twice because I didnt know there was so much carbon on the exhaust port, you can still get away without cleaning like this on a 4 stroke but the 2 stroke engine will get damage and eventually blow its conrod because of the extreme back pressure build up when it gets really hot...I also rode my 4 stroke bike without any of this procedure for 8years and it never really had such problem..however.its very important to do this on a 2stroke engine

[@fidelcatsro6948]

the repair shops never really tell you about this, they simply say it needs repair..if you do this trick every 5000mi on a 2stroke e gine bike its going to last.a long long time..

[@5353iceman]

I never thought of that, thanks.

[@smallengineshop]

tt Thanks for watching!

[@andybecker2693]

The thing inside the muffler that you said looks like “radiator fins” is actually a catalytic converter used to reburn unburned exhaust gases that normally occur in a 2 cycle engine.

[@AzadKhan-yo8fq]

Cant you clean it with petrol?

[@carmeloquiles451]

Thanks you

[@76chyanne]

will this cause trimmer not to start at all i have stihl fs45 new carb took apart clean flywheel and coil i have a nice blue spark but it will not fire,even when i spray start fluid in carb it will not fire thought it was spark but thats isnt the case so what next ,thanks for any help,i dont have a compression tester,so cant teest that im being told rings maybe the problem

[@blakbanshee]

Thanks for the video. Any idea how many hours are on that weedwacker?

[@jonathanbenoit8828]

Why didn't you, use lube for the bolts, and clean up.?

[@clarkc81]

I have a 49cc 2 stroke petrol scooter and I only used it for a couple of weeks when I got it new and now it doesnt start it was starting and cutting out and now it doesn't even try to start so I put a new spark plug on it and new carb checked to see if it was getting a spark and it had a really good spark so I took the exhaust off and lots of oil started running out the exhaust so I noticed every time I pull start it its filling the exhaust up with oil and petrol dono if its the pistons or not

[@jimtonkin713]

Hello. Does anyone know what model that particular trimmer is? I just got an engine for one today and I'm wondering what model it is.

[@TheRyanbiernacki]

penetrating oil works good for loosining up carbon

[@pimpinpenz]

I run seafoam in my 2 strokes, it doesn't hurt anything.

[@sjustice2908]

I do landscaping 30 plus years experience now been running the same Homelite equipment ever since I started back in 79 the exact same original weed wacker chain saws and leaf blower and believe it or not the best thing you can do when cleaning the carbon out is take it apart like in this video and then urinate all over the muffler and inside the engine around the piston the ammonia in the urine brakes that stuff down like nothing I've ever seen let it sit overnight at least 24 hours 48 hours if its really bad and then shake it until it's about dry finish drying with an air compressor put back together will run like brand new and only got to do it every 7 - 10 years! what I do is urinate in a five gallon bucket and I get it about half full that way I just throw the muffler in and let it completely soaked and then with the other five gallon bucket that has urine halfway full sometimes if I am in a hurry I will just hold my weed wacker upside down and dunk the whole motor in and let it sit for 24 to 48 hours with the spark plug removed and the exhaust removed and it will clean everything! when you take it out do the same thing dry it with a compressor and then rapidly pull the rope put it back together will run like brand new again! the ammonia in the urine is the secret and like I said guys been running the same home light equipment for over 30 years now besides replacing a couple pull ropes and spark plugs all original.. take care guys and nice video

[@tndlawncareservices9831]

S Justice is there anyone here tested his concept put yet?

[@CYBERemnant]

2 and a half gallons of urine..........bet that takes some time to accumulate.

[@paulwatson7534]

Not if you invite your friends over for a beer or two!!!!

[@leafer655]

piss on it

[@0truckmafk]

and the fermentation during the time it takes to build that up ffs!

[@staticxmako]

after those 5 screws on that exuast redirector. remove that little 'gasket" its blocking to much flow and cuasing too much back pressure.wich is cuasing this. hope this helps

[@clemonyoungblood1913]

Mattmako Good Morning! Excellent Video. You were using several different tools. What was the tool with the Blue Handle? Where can I find one?

[@666mrjimbo]

ALSO A GOOD THING TO DO IS TO CLEAN THAT SPARK ARRESTER BEFORE PUTTING THE MUFFLER BACK ON. I HAVE REPAIRED A FEW THAT WILL NOT RUN WHEN YOU THROTTLE UP THAT IS A COMMON PROBLEM ESPECIALLY WITH THE 4 STROKE WEEDEATERS .HOPE IT HELPS PEOPLE

[@extra260b]

yep. my gas mix was old.. now it works great! :P

[@Roarkethemerciless]

The above part of the piston (when i look inside) is black. Is this normal ?

[@waynewigger9904]

That helped but its still flat of the throttle

[@dannymccartney1411]

on my Stihl trimmer fs45, the bolts that hold on my exhaust onto the head broke off what can I do there in the head

[@omega12charlie]

just what I needed to know. Thanks

[@smallengineshop]

Thanks for watching!

[@DougHinVA]

so he scrapes on the piston with a metal screwdriver and not dissolving spray? asking for real engine damage on the piston and cylinder...

[@extra260b]

would pouring solvent in the muffler remove oil? because seems like my muffler have a lot of oil in it?

[@joetuihifalani-laumahina524]

check clutch Springs if pull start chord is hard to pull :)

[@Okie-Tom]

Good video, thanks for the information!

[@639Beaver]

You are a smart guy Thank you

[@Roarkethemerciless]

When i used the grass trimmer, the exaust port got black.

[@smallenginedude71]

Hey dude thanks alot I have learnt alot from ur vids , keep it up!

[@chanhducphung2826]

Thank so much for your nice details video

[@tigertruckerman]

My strimmer works fine all though revs loud,then cuts out any ideas

[@666mrjimbo]

YOU NEED TO ADJUST THAT CARB THE H SCREW WILL MAKE THAT MUCH MORE RESPONSIVE

[@danielsniper5308]

What it the engine is not peaking the oil in to pipe

[@killyou1549]

Do a troy bilt 2cycle weedeater soposed to smoke I mix 1galon of 2cycle oil it smoke and it smell like burning oil

[@YaaGirlTiny]

Thanks man. I bet that's the problem with mine.

[@mbud2529]

hi! I have a mcculloch ms4018 that has a sheared off fin on the starter flywheel. right now if u pull on the rope it just clicks any ideas or am I dealing with a bench paper weight?

[@Bulldog_DK]

nice info thx.. easy to fix

[@MrTorrence69]

I tried all that n still it doesn't start

[@rico1319]

Good video thank you very much

[@RUSHNBOBO]

The radiator looking thingy is the catalyst for emissions... don't use a screwdriver or anything metal to remove carbon, it will scratch the hell out of the piston... use a wooden dowel or hard plastic tool to scrape... use a strong solvent or seafoam to soften the carbon first...

[@kachacuaz69]

thank you for the video

[@colonius12]

years ago 1974when selling harleys here in perth western australia an old fella said that the best way to decarbonise his ols two stroke mufflers were to start at one end with oxy actylne heat and then just let it burn itself out so yesterday i tossed my ryobi PLT 3043Atrimmer exhaust and its twin, the homelite F2020 onto a propane gas burner and just let them burn, complete with the spark arrestors and the oily screws. they created smoke like from the pits of hell not that i intend on going there, thank you Jesus and i dont know really but maybe 15 minutes later they were as clean as awhistle and after cooling agentle tapping and blowing would be good enough for them to be re-installed. and since they are all formed in fire nothing will happen to the exhausts as they are all steel just in case you think they will melt. all my initial doubts disappeared the moment I saw the mufflers smoking away and knew they would clean up. go on, go try it.I also use my faviourite scredriver iwth e torx bit, my snap-on T handle rachet screwdriver , the best tool I have ever purchased. bloody expensive back in the early eighties, about $80 usd in those days or $70+aud., oNe last thing google 'walid shoebat' being the most informative mind on the growing muslim invasion and End Time doctrine cos Jesus is coming soon and if you dont have a bible search out a Gideon member in your nearby church cos he'll give you one and they are the best to have since they have their own GPS at the back of them Gods Plan for Salvation. you were more than likely given one when you were in 1st year high school but without the GPS in the back. Its the biggest 'must Have' in your entire life. as I say to the people I give them to, If I dont see you again on earth, get your commitment signature in the back of that book and I will see you in heaven. Bye guys.

[@smallengineshop]

Thanks for commenting and watching the video!

[@rubyallen3169]

That's a good way to scratch the piston why not spray brake cleaner in there and the muffler screen

[@mikerue2423]

Rather than replace the muffler why don't you try soaking it in a solvent like acetone ? Also a solvent like carb cleaner can be used on the exhaust port carbon.

[@Xgamer121X]

the thing inside the muffler you described as looking like fins on a radiator looks to be a catalytic converter.

[@DougHinVA]

Remove the gasket for the muffler and squirt GumOut carb cleaner in it and then empty it out. After excess is drained/shaken out, light it with a propane gas grill lighter and burn off the remainder. (A small brass tube can be hammered into a wedge and that will not score steel to scrape the exhaust port), but get the piston up enough to block any carbon from falling into the combustion chamber... I took the muffler sprayed and shaken out from carb cleaner and then set it on the ground (large opening up) and lit it with a small propane grill lighter. Adding a small piece of paper towel as flame comes out the hole drives up the heat and makes the combustion burn up all traces of the carb cleaner. It will be HOT for a few minutes after the burn out ! Be careful and re-install with a drop of no-rust on the screw threads before tightening the nuts (usually 2 for a small metal muffler).

[@enoxosr1]

good video. at 2.20 when you say screen and then write on the video fins, I think the proper name should be spark arrestor. The function of this is to prevent fires by blocking large carbon flammables.

[@j263426]

hey man i have a weed eater bike and when i give it gas it that moter starts to too slow down and turn off do you have any tips thanks"""""

[@ayyye9459]

Carburetor adjustment fornsure

[@tejr98]

he said it was because not having line on it or it was because they put to much oil the gas mix

[@mattmag3089]

negative, deb. it's a biproduct of burning oil. there is a broad spectrum of 2-stroke oil out there, some of which are cleaner burning, but at the cost of protection. high reving motors need a good deal of lubrication, and some of it just doesn't completely burn away. im head of maint. at a landscaping company and we have not yet, in 6 years, had one lean seizure or major failure in any of our 2-strokes (edgers, whips, blowers... all used at full throttle most of the day, most of the year). we run Opti-2 at 50:1, a quality oil. carbon build-up is inevitable in a well protecting 2 stroke oil. amsoil, for example, has dominator and interceptor. both great oils for PWC, motorsports and sleds. interceptor is cleaner burning, for "recreational riders" and dominator is for "racing applications" because of it's artifacts that hang around and protect (as well as foul) in extreme conditions. Machines that are raced usually do top end rebuilds quite often, so carbon fouling isn't an issue. long story long, if your small engine is still running after years, but you have carbon build up, smile. you're doing the right thing!

[@outdoorsman310]

seafoam is great!

[@TheBeatenPaths]

Or....you could use Amsoil Saber 2 stroke and never have to worry about this.

[@GoodBadUglyest]

I have that same screwdriver!

[@xtwicex1]

Good info

[@jonb6903]

I have the same weed eater and I can't figure it out I've changed spark plug the muffler is fine the fuel lines are perfect. The fuel filters perfect tits sucks up the fuel when you pump everything turns nice and neat of check the heads of checked everything on it be after some reason it will not start against the fluid in there it's got the spark air cleaners clean I have no idea what else is wrong could it be a bad gasket on the carburetor

[@smallengineshop]

Is the spark plug wet with fuel after you try and start the engine?

[@jbbrown5847]

You just described the exact problem I have (wet plug) won't stay running and lots of fuel come out exhaust (I think that's where its coming from.) I've replaced fuel lines and going to rebuild carb & make sure the adjustment screws are where they should be. Anything else I should do ?

[@BSsnowboardTR69]

Seafoam. Seafoam. Seafoam.