How To Tell WHY Your Piston is Destroyed 

Get new piston kits here--- amzn.to/2kbqoaT Click here for my website--- www.stevessmallenginesaloon.com/ Click here for my Parts and Tools Store---- www.amazon.com/shop/stevessmallenginesaloon You can see the "cheat sheet" report in the "community" tab on my channel!

I wish you could make a course for 2 stroke dirt bike owners. These people warming up their brand new bikes are destroying their $12000 machines then blaming the manufacturer for c***** engines. It's all over RU-vid and it's crazy and I see it all the time. As soon as they fire them up they rev the cra out of them. And claim this is how all 2 strokes should be warmed up. Much education is needed in this department. Awesome video thanks

This video is nowhere dragging or boring, its actually very, very informative. I have learned a lot. I'm a typical do it yourself. After watching this video I decided to disassemble my leaf blower since it wasn't working, removed the piston, it had that varnish tar, I cleaned it really good, lube it put back and my leaf blower it back in business.

Appreciate the time and effort that you always put into all your videos. This one especially. On the cold seizure failure, the piston needs to expand but the cylinder needs to warm up too. Parts of the cylinder are not subjected to as much direct heating as other areas are. Clearance on the exhaust side of the piston is probably the first casualty of loading up a cold chainsaw. Again, great job on all the videos.

Keep it up STEVE , I have worked on small engines for 42 years and your right on with your instructions! I like beer to!

Thanks ALOT steve! Im an arborist and by watching you video i learned so much about chain saw. Im gonna share this with every one at work.

Yessir Steve is great I wish I was his neighbor, not just to get EXPERT advice about my two-strokes but just to sit around drink a beer and conversate. Great video as usual, keep up the excellent work SteveO, your the man!

I'm so happy to finally be learning about small engines. Thanks Steve! My Stihl Farm Boss is finally getting some much needed attention. My cylinder looks the overheated one, and yes, I'm surely guilty of cutting with a dull chain. Almost all the scoring is on the exhaust side, but there is also some on the intake side, lined up exactly with the piston ring locator pins. Why would that be?

I had coffee with this (10 AM) and still thought it was interesting!

Wow! Thank you for giving me (and us) such great info. My step jerk was a logger when I was a child. He taught me the basics of felling, but not the basics of chainsaw mechanics ( I don't believe he new them), so the mechanics have been a mystery to me. Until I discovered you on RU-vid! Because of this, and other, videos of yours, I was able to tear down my wife's old husky 40. (way easier than I ever imagined) It had stopped working due to a clogged fuel filter. Fixed the filter, but then it soon started having problems. Thanks to this video I tore it down and found the piston to be worn in the exact way that your video showed when starved of fuel. I am planning to replace the cylinder head and piston. I will look to see if you have a basic "things to replace when rebuilding chainsaws" video. Ps. I loved the "magic Sink". Gives pause to examine our male privilege. Keep up the good work and fun!

Great videos Steve! Well done, educational, a bit of humor included. What more can we ask for? Many thanks for your time and effort to create worthwhile videos. :)

Your stuff is great Steve....especially the Magic washing machine...... One point you didnt fully make on 'cold seizure' in a chainsaw is that the piston expands faster than the heavier cyllinder, especially the exhaust side of the piston...you either left out the cyllinder's role in the warmup, or I didnt hear right.... great vid....so far all my chainsaw compression losses have been leaky seals and carb/air leaks....frying the exhaust side.

Hi Steve. Thanks for all the videos. I've been a mechanic now for many yrs-thru the yrs a mix of cars and small engines. These days just small engines for a large landscaper in VA (along w/the hustlers and grandstands). Sometimes I like to watch to confirm what I know and sometimes to learn more of what I dont...hence this video. Its funny the cheat sheet is from echo because its the brand I wanted to take on when I had my own shop unless it was a chainsaw where I would go with the stihl. My boss just killled his favorite ms660 so I will print down (in color of course) the sheet and compare to see the cause. I think it ran too lean or too hot or both because the plastic was untouchable above the head and the exhaust side was scored. As far as the oil in my opinion....I'll stay with 36 to 1 all day everyday and unplug those arrestors with the torch verses torching a motor any day! I dont care how good that oil is 50 to1 is just asking for trouble-rediculous. Keep on videoing!!!

The cheat sheet is just like a spark plug diagnosis sheet. Jugs instead of plugs. I like. Thanks Steve.

Excellent video. Now I need to take apart my 2 stroke on my ‘83 Yamaha G1 golf cart to determine the cause for the failure. Again awesome video and easy to understand

Awesome taught me a lot. I am 99% sure mine was overheating now, hopefully I can fix the bloody thing now

Thanks for the video. Helped me diagnose sons dirt bike issue. It is between a lean scenario and overheating, which makes sense, because if lean, there's also heat! This helps as I can figure out it was my mistake with the jetting and needle position on his carb. And also a bit of training a 13 year old that always pinning it is fun, but mucho hard on equipment. Live and learn, thanks for helping with the learning part!

Commin from a goped rider, i love your videos, helped me out allot with my goped 46cc engine, thanks.

Awesome video Steve. I started rebuilding saws and you need to know why the piston is damaged before replacing.

Great video Steve. I live in a house at our local VFW. I main the grounds and lake on property so I try and do my own repairs to save the VFW much needed $. This vid will definitely come in handy

Fuel restriction , lean running, .... don't underestimate the fuel filter, even if you just replaced it. Some of the fuel filters I've been using , specifically 38-9227 from Rotary(503443201 substitute) had loose plastic flashing material and flopping around inside the filter, blocking the filter outlet, causing a "check valve effect". That would certainly cause a lean condition.

Thank you so much, Steve. I have been operating 'in a vacuum' trying to understand why my rebuild Stihl FS85 seized. I knew it overheated but I was ignorant of the many causes. I failed because I didn't examine the Critical Evidence. 08AUG2018

Good!!! Morning Steve! !! From new Zealand. Beautiful morning here . It's Sunday hehe. Cool Cheers.👍

Very useful info for my weed eater and chainsaw. Thank you, Steve!

I lived and learned some of these!

Good job! Maybe do something about chipped or cracked piston failures.

Fantastic video. As usual you're setting the standard for your video topics. Please continue to keep educating us with your videos. Thank you very much. Can you help us get copies of the ECHO failure analysis report?

I think you covered most everything. Cheers!

Great video by Steve once again. Nothing dry about this. Informative and interesting as always.

A wealth of usefull information in this video, thanks Steve

Excellent video! Wray in Ohio

Perfect. Great job. I've been working on the same backpack. Just driving me BS crazy. I'm saving this video so I can show my buddy how he killed his backpack

I don't have a lot of faith in shops anymore after bringing my chainsaw to 2 different certified Stihl dealers where they must hire the cheapest labor off the street to work on equipment. I had brought my saw in because it wouldn't idle properly when it was warmed up and set aside to move cuttings out of the way. When I got my saw back from the shop, it would stay running but it wasn't long before it was destroyed as they had leaned the mixture out far too much where it burned a hole in the piston with the exhaust side severely scored. I've purchased an aftermarket engine since Stihl parts aren't easy to find online and with the help of your videos, I should be able to properly adjust my carb to the right mixture & settings.

Awesome as always. Clear and concise.

Awesome video Steve , you can't emphasize enough that leaning a carb out on a 2 cycle motor is taking away most if not ALL of its lubrication . And also have you had any issues with the Stihl MS441C saws having issues with spark plugs backing out on their own ?

That cheat sheet is really cool

My uncle gave me his Ryobi weed eater and I used it for a year. It got an oil change after 1 summer of use and the next fall we tried using it with a pruning attachment but it locked up. So I took it apart and the air filter was non existent and the piston chamber was filled with a mix of oily crusty goo. I think it needs a new piston with rings now haha.

Thank you for the video, very good information. I know you made this video some years ago, but I have a question. If there is scarring on the piston and/or cylinder wall will that cause compression problems. My Echo weed eater starts, it revs, and can run the entire time I hold the throttle open. But as soon as I release the throttle it dies. I pulled the cylinder off and there is scarring on the piston. I’m sure my piston is shot. I put regular 87 gas in the tank and used it quite a bit, then one day it just died. I put 2stoke fuel in there, but it won’t stay idle. I inspected everything else, but the piston seems dead.

Excellent video, well explained, presented and illustrated. Question... a Stihl blower (as that's what I'm working on), has had someone install the piston backwards. Foolish me failed to inspect exhaust outlet before installing new carb... I saw the piston ring pin in the exhaust port later! How about a small segment on how to diagnose starting issues - in this case, I put a little fuel in plug and it ran, real, real bad - if at all. Them checking plug it was totally dry. Piston (having disassembled is scored on the retaining clip side of wrist pin (perhaps not related?)... just a thought. Have a great weekend - have a frosty on me! Best

Very well explained Steve, cheers to that! As usual you always nail it

Thanks for sharing all important info, very enjoyable to watch & understand.

Hey Steve, your presentation was done very well. Thanks so much. I'm slumming with Budweiser Red as I watch this vid. I'm a Rolling Rock guy. I prefer ale to lager. Thanks again buddy.

Absolutely brilliant ! Many thanks......all the way from London.

Thank you 4 your video. How many years of experience with 2 strokers are you having ? Peace with you from old Eu.

Thank you, thank you! Great instructional video, Steve!

Brilliant video, thanks! I know this has been asked, but can many of these scored piston/cylinder issues be somewhat prevented by running a 40:1 mix instead of a 50:1 mix? Thanks Steve.

How could this be dry, I had 2 beers watching it!

Wow, loads of great info in this video. Thanks for sharing this.

my new go to guy...right on man.

Good job steve

nice explanation

I love your videos my friend, can u answer something for me. My Husqvarna 125b blower. The cylinder head looks good to me and so do the piston. The only way I can get it to run is put a little oil in the plug hole. I know it’s low compression. But which is wore out , both of them?

What would you suggest that would cause scoring on both left and right of the poston? Both sides just in front of the piston pin.

Omg your video hits mine on the snail

Jeez, I hope you're learning to play the harp Steve, cause you're going straight to Heaven.

Another great video. Can you talk about ethanol free fuel vs gas and what problems it can prevent?

Good education again

I only buy 91 octane gas for outdoor power equipment and I know manufacturers can tell if you have voided your warranty using low octane gas. Could you please explain.

Thanks ...

Thanks for posting this video.

Love the visuals but could you please explain how you can hole a piston by having the wrong timing or running too lean? Also what are the signs leading to this that you could avoid this from happening ? Also,does engine pinging lead to engine damage and how? Thanks

Excellent content in this video. Thank you!

Fantastic learning videos...love them, thankx.

What causes a poulan leaf blower to start pinging after a half hour of running?

Excellent video Steve

I think I overloaded and overheated my little machine trying to cut a lot of hard wood. Maybe I didn't wind out the high speed carb jet enough as well. Engine won't start and piston looks a little scratched as I look through the exhaust port. However engine feels like it has good compression when I turn it over with the starter rope. Could it still require a new piston/ piston ring?

Thanks for helping us!

Cool video Steve.. I can do the same thing with the Mazda Rotary (Wankle) engines I work with.. could you please do a video on why to use bar oil and not just regular engine oil in the chain saw..

Sometimes, especially with cement saws, the piston can be scored by not having good maintenance habits with your air filter.

Hey Steve, love the show & content. And the beers and/or cold Beverage in garage while fixing , fiddling around is a must & common amongst many of us . 😎👍🏽 Question for ya . I got a stihl ms 271 ( not a farm boss either, ya I know , odd but that’s what it is . Anyways my chainsaw is toast. Piston /rod /housing is toast. Rings are melted into piston. And I’m so careful and keep stuff clean and maintain it yet I admit I wasn’t aware of taking the clutch off and other wheel , etc and cleaning and blowing it out and too bad cause it looks new still almost. And I use it to help people out all the time . Didn’t even use it for my house. Oh well . Anyways is it possible to swap a motor from another stihl saw ( bigger more powerful) and put it on the ms 271 frame? Or do I need to buy new engine that costs about as much as new one especially once labor is added ? It was like $600 few years back . I know They’re proud of their stuff. And I’m in need of good one . I help out older and less abled with it and I’m 45.

Good movie

6000th thumbs up. Your the best

Great information bud. Thanks

Really enjoy the videos and thanks for sharing your knowledge Steve! Have a Stihl 064 bought used. It wouldnt idle well so i pressure/vacuum tested the crankcase and found bad seal on flywheel side. There is some play in crank bearing on flywheel side but thought i would see how long a new seal would last first, before going further. Vacuum tested fine with new seal and started right up. used about 30 min but cant get idle right. Without tearing apart again and vacuum testing to see is seal is bad again, how long do you think seal would last with some play in bearing (minutes,. hours...) ?? Also, what are signs of starting lean seizure, other than failure to idle? It does NOT rev up when held on either side but does bog down one or both ways .Would it bog down first while cutting? When reving up it seems to be 4 stroking and not running too lean... would exhaust show excessive heat, etc? Piston has slight scoring above rings from before but rings are free and compression seems good pulling.

I thought all them pistons were beers at first I was thanking oh dam lol

So, I should go check the torque of the carburetor mounting screws to the intake? I read your Jedi mind. Nice work Sir.

In a smooth bore, 4 cycle, the ring end gaps are spaced so they're not riding on the thrust face, but as the engine runs they can rotate. On a 2 cycle, that's deadly, the end gap at one side of the port would see the other end of the ring pop out and have to slam back into the ring land on every stroke, resulting in engine destruction in seconds. The locator pins actually serve to keep the end gaps OFF the intake OR exhaust port and ride up and down on the bridge on the cylinder wall between the ports on the left or right of the ports depending on engine design. You can actually go to college for this stuff. I made my employer pay for it all.

Helloooooo: how can i remove the piston from a short block motor . This is all one piece cylinder and block and need to pull out the piston , this is my homelite blower that has no compreccion and i want to take a look in the ring.. thankyou i be wsting for your answer

Exilent

Hey Steve. Love your channel. I have a question, I recently bought a Stihl MS271 and the dealer told me that Stihl no longer uses needle bearings for the piston pin and told me to use an ”extra shot” of oil directly into the has tank after adding the proper mix for the first five tanks. Have you seen this to be an issue? He said the new design is a bushing that is too tight on the tolerance and tends to seize before it wears in and the extra oil helps.

Yeah and they always come in on the exhaust side so you have to take it apart and turn it around

In a nutshell Steve people if the take care of there small engine's they will last a long time very good video

can a high level of ethanol in a premium gas cause scoring on the piston and engine failure. Compression is now 50PSI. It was running and then just stopped.

What about a piston damaged by LEAN/LUBE failure that also has a burn puddle melted into the crown right under the spark plug?

Not boring at all Steve

Years ago, 1950s and 1960s the recommended mix was 1/2 pint SAE 40 non-detergent motor oil to one gallon marine white gas (non-leaded) gas. How far we have come since then. I think that this was I imperial measure.

Great info!

Just ruined my stihl saw rod bearing was coming apart little bit at a time putting small bits of metal in the cylinder

Would never take my piston of but I will be doing now thanks steve

Sorry to double-post but unrelated Q on this--- is replacing the piston/cylinder the only option if they are bad, or can they be "ported" & "sleeved"? Think those are the terms I'm looking for... While I don't know for sure yet (not at the point of firing it up yet), I suspect my 1977 project saw (poulan XXV/25d) may be bad and while I do fully intend to get another unit (just for parts- maybe even the engine!), I can't help but worry that this may be a very common problem on these older saws because, at least for mine, the air-filter had literally disintegrated - I can't imagine that means anything except "every last bit of it went-through the chamber on its way out the exhaust"! While it's simple to replace the long-ago-evaporated/crumbled fuel lines, the air filters doing this would (I'd expect) mean the engine had to 'eat' the filter as it went....My compression feels fine (shoulda got the tester when buying my tach.!), however when I have the muffler off and am looking into the exhaust-port while turning the flywheel I can feel that, as the piston approaches the top/spark plug, it moves very smoothly from the bottom of the cylinder, smoothly past the lower/first edge of the exhaust-port, however once the top of the piston passes the 2nd/top edge of the exhaust-outlet it feels FAR rougher, almost-as-if the exhaust-outlet itself were slightly 'bumped inward' at its top edge or something (although there's no corresponding piston-marks as I'd have expected, the piston&cylinder *look* un-scored, just some varnish-streaking on part of the cylinder-wall that I'll be wiping-off -- haven't decided yet if I should just reach-in with a long cotton-swab, or if I should learn how to dissemble the entire area and do it right (think I'd do that if/when I get the rest of the problems sorted & actually get it to turn-over, would then immediately turn it off and begin a proper overhaul of the piston/cylinder) Making this saw (or another unit of the same model) work is majorly important to me, I know it's not an economical way to get a saw but I already have saws I just want this vintage, neon green top-handle to work, think it'd be an awesome saw to bring on jobs :D Thanks again for all you do man, your series is literally one of the best 'educationals' I've found in ages, I went from knowing nothing about 2-strokes to actually doing amateur rebuilds (not just chainsaws, my awesome Husq 125B blower was a trash-pile pickup that I got working and now use daily, also have an Echo hedger that I'm (pretty sure!) almost-done getting to work, would never have gone this path if it weren't for your channel and, now, I can't imagine I'll *ever* "grow out of" my interest in 2-strokes!!!)

...you had me at go grab a beer! Kokanee nuff said...

good vid well done ///you just down the road from buckin ???

Do have a video to show how to rebuild the chainsaw?

Great video super informative

my electric weed wacker piston looks great , its invisible so no scores. i like the 4 stroke hondas but the new cordless tools are getting pretty robust, here they have to use cordless for night work by law as not to ruin peoples sleep , man some of these things have some real power and cut for ages.

Good video amigo

Got a question, stihl ms311, compression 130psi. Starts and runs well. Except if chain Brake is engaged it will stop. I have not adjusted the carb yet, or pressure tested the saw. The piston in the exhaust side shows minor scoring. I suspect a seal leak but wanted to get you opinion Steve. Thanks

Steve the question I have is a 2 cycle p26 pioneer chainsaw has 2 rings piston the pins that keep the rings from rotating are flush with outside of the piston and the rings were the gap is are square allowing compression blow by threw that gap is that ok

Thx so much I could only run a blower with the choke on and when I took it apart it was the overheating one but I think it was a cold seizure but luckily it was my dads blower. 😂

Will a scored piston make an engine hard to pull? Nearly to the rope breaking point? The engine runs strong but the piston is scored, but it is extremely hard to pull.