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


**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.



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

  1. 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.  

  2. 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!  


  4. HHO Gas Carbon Cleaning is the only way to remove carbon deposits internally on a internal combustion engine without any side effects like traditional carbon cleaning. You may go to my website hhogastechnology.  com or go to E-Bay and search HHO Gas Technology Engine Carbon Cleaning Machine.

  5. 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.

  6. 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

  7. 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!

  8. 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! 🙂

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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

  14. 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!

  15. 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!!!

  16. 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.

  17. 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.

  18. 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!!

  19. 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

  20. 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.

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