Just trying to understand piston and cylinder damage. I can see varying differences in piston condition looking through the exhaust and intake ports. But this does not give me the whole picture. I have saws that start and run well, but I have seen scratch lines on the piston looking through the exhaust port. Some even surprise me with still testing 160 to 180 PSI on compression testing. I wonder if it is prudent to disassemble and inspect the cylinder, rings, piston and ports to identify and remedy the cause prior to more severe damage, or run the saw till it needs piston, rings and/or cylinder replaced. Some of my saws that I have owned since new look great. Mirror-like surface with no material transfer or scratches. Other saws have light marks that do not bother me. Others I am unsure of and surprised that they start and run. Looking to see what others recommend. I am thinking to take them apart and determine the cause before more damage occurs.
Amazing how bad some saws can look and still run. I'd be thinking in terms of saving the cylinder vs the piston. Light hone of the cylinder, then a new ring or piston assembly. Got away with just using sandpaper before I bought a set of hones. Actually worked ok.
Likely go aftermarket parts unless history and overall condition of the saw warranted throwing a lot of money at it. Not that hard to keep a saw running if you stay ahead of major failure. We can debate OEM vs AM parts for a long time, but the cost of the parts vs value of the saw when finished ought to make some sense.
An old 372 with a lot of hours on it is certainly worth an AM piston, or complete top end. But unless it's a low hours, or very well taken care of example, it's hard to make a case for a new OEM kit at $300+.
If I may continue my rant.....us folks in the online saw world have been skewed a little off course as the discussion is often about porting and cookie times vs just getting some wood cut. Yeah, it's fun, but I'm a little embarrassed about how much I was drawn into that part of the hobby. Every saw doesn't need to win a race; how about just completing a job?
Lotta fun can be had getting older saws like that pile of 54's back on the duty roster. Why I have 8 or 9 49SP's and 52E Jonsereds that run. ffwave
I did search the forum and online, but not a lot of good photos. More of just take it apart and not to reuse a damaged piston. Comments on poor quality after-market jugs. And to see if your finger nail will catch on the grooved marks. And it is a gamble to keep running the saw without addressing why the scoring is occurring.
Reliability and function are my priorities. Not out to win a race. Except for the longevity race. I prefer maintenance over emergency repairs. I did get the 162SE out last week. I stopped cutting with it as I noted it idling faster than normal and the idle speed would get quite high. Like a runaway diesel. I choked it to shut her down verses the kill switch. Want to cool it down as quickly as I could. I'm worried about piston damage, but will hold judgment until it is disassembled.
(https://forestryforum.com/gallery/albums/userpics/64252/162SE20250405_141530.jpg) (https://forestryforum.com/gallery/displayimage.php?pid=358747)
Interesting subject .When new the cylinder will be almost perfectly round and almost no taper as will the piston be .After a lot of run time those won't be .Certain forces such as piston tilt will cause ovality issues etc which most of the time the piston rings have formed to that .New rings in a worn cylinder take a while to "break in " IMO to attempt to correct issues with a plated cylinder would be very difficult .I have a Lisle precision hone with the stones for plating but because of being so thin I don't use it for that but I have for iron lined engines ..
Again my opinion piston tilt plus a thin mix oil ratio combined with a less effective air filtration sytem contribute to worn piston skirts .For example the horizontal piston 10 series McCullochs of old had terrible air filters and most of them will show that on a tear down .However a rather long piston and more rich oil /fuel mix used saved most of them from the scrap pile .
However as has aleady been said some engines might look like junk but run like a top in spite of that .That I have no theory about .
Some things I have noticed:
1) As long as the piston ring(s) is free, a saw can run decently with a pretty beat-up piston. Not saying that is a good situation, but I have been amazed more than once. That said, if there is considerable scuffing or light scoring on a piston, there has to be something going on, even if the saw hasn't blown up...yet. Which leads to such possibilities as:
2) Carbon scoring. Whether soft or hard, from deposits on the top of the piston or in the exhaust port, carbon is not a piston's friend. It can also get into the ring lands, causing the rings to stick, leading to more blowby, which only exacerbates the problem. Poor quality oil and/or fuel, a too-rich carb adjustment, or failure to run a saw wide-open like it was designed to can all contribute to excessive carbon production, and when that stuff gets between the piston and cylinder, nothing good happens. Most customer saws that come across our (my Dad and I do our best to share :wink_2:) bench, exhibit at least one of these, and usually multiples of these symptoms.
3) Dirty, damaged, or no air filter. The vast majority of homeowners and farmers in our area pay zero attention to their air filters. Sad to say, probably half of the local professionals (aka arborists) are at the same level. The result: fines + dirt = lots of intake side scuffing and pitting, and just more abrasive material period inside the crankcase and in the cylinder to chew up pistons and gang up with carbon to commit more unspeakable atrocities :wink_2: .
4) Of the badly-scored pistons/cylinders that we have seen that were not the result of metal fragments travelling through the engine, probably half were seriously overheated (dull chain, packed cylinder fins, etc.), about a quarter were the result of an air leak, and another quarter or so were straight-gassed. We have about a 90% success rate in saving the cylinder in such cases. Having a look down the plug hole and through the exhaust and intake ports is always a good place to start. In the process of getting to them, you will be able to tell if the saw has been getting a steady diet of dirt, fines, and/or junk oil & fuel. Even inspecting the contents of the bar oil tank will speak volumes about how a saw has or hasn't been maintained previously. Once you actually get to the point of viewing the piston through the exhaust & intake ports, you should be able to see corroboration of your initial inspections of the spark plug, air filter & airbox, carburetor, intake block/boot, spark arrestor & muffler. Are the cylinder fins packed with sawdust, pitch, sap, or other debris? If major scoring is apparent, then checking for air leaks or other potential causes BEFORE pulling the cylinder can save a lot of time, effort, and possibly throwing more parts than necessary at a project than it is worth. Of course, if you are just harvesting parts, go ahead and strip it down.
5) If there are signs of metal having flown through the engine, a complete teardown is needed to find the source and remove any leftovers if a rebuild is on the agenda.
If there is "minor" (everyone's definition will be different) damage to the piston (for example, maybe some signs of light carbon scoring), but everything else checks out and the saw runs well, you might be fine with cleaning any excess carbon out of the exhaust port, and merely running a good-quality oil/fuel combo to prevent further carbon accumulation on the top of the piston. There are quite a few JASO FD-rated oils that have to meet very low-ash and high-detergent specifications that will keep carbon deposits to a minimum (and some even claim to reduce existing carbon deposits in an engine). On the other hand, if the thought of any carbon keeps you awake at night, maybe a complete teardown and cleaning of the piston and cylinder will be worth it for the peace of mind ffsmiley
Just my two cents (which is exactly what it's worth :wink_2:)
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Thank you Magicman.
Two 154SE models with piston scuffing. Both are running well and performing as expected. 5 tanks of fuel through one and 3 through the other.
(https://forestryforum.com/gallery/albums/userpics/64252/154SEpiston20250330_105936.jpg) (https://forestryforum.com/gallery/displayimage.php?pid=358867)
(https://forestryforum.com/gallery/albums/userpics/64252/154SEpiston20250330_110102.jpg) (https://forestryforum.com/gallery/displayimage.php?pid=358865)
(https://forestryforum.com/gallery/albums/userpics/64252/piston154SE20250315_083559.jpg) (https://forestryforum.com/gallery/displayimage.php?pid=358866)
The marks on the side of the piston did not extend up onto the surface of the piston ring. Compression test on both were 160 to 180 PSI. One was higher than the other by 10 PSI. Both past the rope hang test. Both also passed vacuum and pressure test prior to me disassembling and repairing. I compared the piston view with an almost 20year old 327P5 I took the muffler off of. That one was spotless. But I have owned that one since new.
Yikes, they look awful. Run em til they give up the ghost? Or, pull and clean the jugs to preserve them? Light hone and AM piston would be good preventative medicine.
In anticipation of the expected aftermarket argument.......these saws all seem to have a lot of run time on them. IMO, such saws can be kept running very economically with AM STUFF. I KNOW it's not as good as OEM. But I think repair parts ought to match the job to some extent. A new OEM kit is fine on a low hours, well preserved saw. Or a full bottom up rebuild. But I wouldn't burn such parts on saws that have obviously lead a hard life. Or put simply, should you mate a new top with an old bottom? Not in my book.
Longevity? Even if the AM stuff only lasts half as long as the original, the fact that most of us split our run time over so many saws, suggests it should not be a problem. I have 5 54's myself. Also have a new, OEM (and NLA) top end. Only my 154SG is nice enough for that kit. But.......it's in great shape and sees little use. So the chance of me frying it and needing the new one is pretty remote. The 254 I run the most received the AM piston treatment 10 years ago and runs great. Ugly old girl, but one of my favorites. ffsmiley
First one looks like a mild lean seizure at some point, Dave. The ring being free shows that someone shut it down just in time before totally frying it. Still, it looks like there is a fair bit of carbon buildup behind the ring and it is definitely worn. The second one is obviously not as bad, but the couple of deep scores in the piston indicate that something was floating around in the saw at some point. In this case, you still have two good cylinders worth preserving, so I agree with Spike60 that new pistons and rings would be worthwhile.
Quote from: Spike60 on April 16, 2025, 11:10:49 AMYikes, they look awful. Run em til they give up the ghost? Or, pull and clean the jugs to preserve them? Light hone and AM piston would be good preventative medicine.
In anticipation of the expected aftermarket argument.......these saws all seem to have a lot of run time on them. IMO, such saws can be kept running very economically with AM STUFF. I KNOW it's not as good as OEM. But I think repair parts ought to match the job to some extent. A new OEM kit is fine on a low hours, well preserved saw. Or a full bottom up rebuild. But I wouldn't burn such parts on saws that have obviously lead a hard life. Or put simply, should you mate a new top with an old bottom? Not in my book.
Longevity? Even if the AM stuff only lasts half as long as the original, the fact that most of us split our run time over so many saws, suggests it should not be a problem. I have 5 54's myself. Also have a new, OEM (and NLA) top end. Only my 154SG is nice enough for that kit. But.......it's in great shape and sees little use. So the chance of me frying it and needing the new one is pretty remote. The 254 I run the most received the AM piston treatment 10 years ago and runs great. Ugly old girl, but one of my favorites. ffsmiley
Not much of an argument for someone to attempt making, Spike, seeing as there are no OEM pistons available for these anymore, at least for us mere mortals :wink_2:
I really have no issue with decent AM parts, especially where OEM is long gone and/or stupidly priced. I have had very good results with the Cross Performance 254 piston kit that comes with a Caber ring. I know that some of Cross' stuff isn't the greatest, but these have been fine in the two 254s that I have ran them in. Didn't pay full price, mind you. Waited until they were on sale for 80% off, and bought a few. Haven't had a lick of trouble with them in five years. A decent-to-good AM piston with a top-quality AM ring in an OEM cylinder beats a dying OEM piston any day, in my books.
Just my opinion, but it's a lot harder to build a good cylinder than a good piston. And those OEM 154 cylinders are among the best. Running them with the compromised pistons until they finally fail and then possibly being beyond saving is more risky than running new AM pistons, in my mind. There will also be a lot less transfer to clean up on the cylinders now, rather than more, later.
That said, a guy has to be ready to DIY the quality control on AM parts himself. Cleaning up any sharp edges or casting marks and possibly massaging the windows in the piston are all on the table to try and ensure best results. I knocked the edges down with a bit of 320-grit emery cloth and that was all that the particular pistons I got needed. Five years later, I honestly can't say if the quality will be better, worse, or the same.
Will be on the hunt for pistons and rings. Thanks for the great advise.
The Meteor quality is very good, probably as good as OE, you should be able to pick them up in US, if not the Greek has them in stock,(DLA engine parts) top guy and ships quickly.
Found an OLD OEM piston (orange and blue box) . Figure it's waited long enough for a new home, so sending it out to Dave, along with a Forester one. I knew the complete kit was NLA, but I didn't know the pistons were also gone.
Great analysis CJ; I'm with ya on all points. One being that it's easier to make a piston than the jug. Why I think an AM piston in the factory jug is the way yo go if the cylinder is usable. You get the more accurate casting and better materials than you'd have with AM cylinders.
Still, a complete AM top end is not the lame option some folks make it out to be. Lot of wood has been cut those things. Especially when it's the only option. In that situation, it ain't OEM vs AM. it's live saw vs dead saw. ffsmiley
Keep em running!
I put a Bailey's Big Bore kit (which I'm sure is AM) in a Jred 2171. It was probably 5 years old or so, not a ton of hours but it still didn't justify the $350 oem p&c. I think the Bailey's kit was around $125 at the time (this was probably 10 years ago) Everything lined up and it went on well. Runs good, and it gave that saw noticeably more power, I think it made the saw 75 or 76cc?
I did a neat trick and ran that saw over with my skid steer🤦🤦🤦 It needed a new tank and handle, so I had a local guy that does saw work put a used one on. Got it back, filled it with gas and fired it up and realized fas was pouring out of it. Put it under the bench and haven't picked it back up. One of these days🤷
Quote from: FATBOY2017 on April 16, 2025, 03:01:55 PMThe Meteor quality is very good, probably as good as OE, you should be able to pick them up in US, if not the Greek has them in stock,(DLA engine parts) top guy and ships quickly.
Couldn't agree more, FB2017. Close as you'll get to OE in an AM part at a fair price. Probably 90% of the AM pistons my Dad and I use are Meteors. Northwood Saw, in upstate NY, carries one of the better selections in the US, and competitively priced, too. Have also ordered from DLA when Northwood is out of stock. Good guy.
Quote from: Spike60 on April 16, 2025, 05:02:54 PMFound an OLD OEM piston (orange and blue box) . Figure it's waited long enough for a new home, so sending it out to Dave, along with a Forester one. I knew the complete kit was NLA, but I didn't know the pistons were also gone.
Great analysis CJ; I'm with ya on all points. One being that it's easier to make a piston than the jug. Why I think an AM piston in the factory jug is the way yo go if the cylinder is usable. You get the more accurate casting and better materials than you'd have with AM cylinders.
Still, a complete AM top end is not the lame option some folks make it out to be. Lot of wood has been cut those things. Especially when it's the only option. In that situation, it ain't OEM vs AM. it's live saw vs dead saw. ffsmiley
Keep em running!
Spike, you are a straight-up mensch! Not like we didn't know that already, anyways ffsmiley
Dave, that orange and blue box is worth at least 15 psi of compression on its own ffcheesy :wink_2:
And it gives you a great opportunity to compare an OEM to an AM piston. You'll see where the money goes, but also why AM is still plenty good for us firewood guys, especially with a bit of fettling.
Totally agree on the complete AM top ends, Spike. Case in point: my Dad just finished up a 268 XPG. No 268 closed-port jugs in the parts bin. Obviously, the OEM closed-port top end has been gone for ages, being supplanted by the 272 which is still available OEM. But he wasn't about to drop $400 CAD to do so. Meteor to the rescue at half the cost. Will anybody using the saw feel the difference? Highly unlikely. It just feels like a very strong 268.
Live saw beats dead saw six ways to Sunday ffcool
Can't put it any better than you: "Keep 'em running!"
P.S. That would make a great T-shirt :thumbsup:
CJ, where are you from? Northwood saw is just across the Hudson from me in Dutchess county. Sal does have a nice selection of stuff. Never met, but have spoken to him a couple times. I like that he doesn't re-box and brand stuff like so many others but do. A VEC piston comes in a VEC box. In which he has most of the classic Jonsered models. Glad you mentioned him. Lotta you guys should take a look if there's something you've been unable to find.
About an hour east of Edmonton, Alberta, Canada :sunny: Northernmost city in North America with a population over 1,000,000 for your completely useless fact of the day :wink_2:
Very competitive pricing on Caber rings from them, as well. We have gotten a couple Episan pistons from them too, when nothing else was available. Pretty decent quality there for the price. Never talked to Sal personally, but their customer service has been great. They don't charge an arm and a leg for shipping to Canada, either. And like you said, you know what you're getting in the box. Fair prices + proper customer service = repeat customers. What a concept?!
You can tell it's a place run by real saw guys that want you to be able to keep your stuff running. Far too few of those around anymore.
Wow, about a thousand miles further than Dave. Doesn't look like we'll ever talk saws over a couple beers, does it?
Some of the nicest AM kits were the Tecomec ones from Italy. Used to get them from Tilton equipment, who was the Jonsered distributor. I haven't looked for alternative sources, so I don't know if they are still available.
I did use a couple of their kits for tree guys wanting to keep their 242xp's going after the OEM kits were gone. Worked great.
Quote from: Spike60 on April 17, 2025, 11:11:24 AMWow, about a thousand miles further than Dave. Doesn't look like we'll ever talk saws over a couple beers, does it?
Sadly, no smiley_thumbsdown
But glad for forums like this. Better than nothing ffsmiley
Love watching you and Walt on the Tube, too :thumbsup:
Quote from: Spike60 on April 17, 2025, 11:21:39 AMSome of the nicest AM kits were the Tecomec ones from Italy. Used to get them from Tilton equipment, who was the Jonsered distributor. I haven't looked for alternative sources, so I don't know if they are still available.
I did use a couple of their kits for tree guys wanting to keep their 242xp's going after the OEM kits were gone. Worked great.
There are still a few older Italian Tecomec kits on the Bay. Most are overpriced, but there are some decent deals still to be found with patience. The name is still out there, but the newest boxes are no longer marked "Italy", so I'm thinking they have moved production to Asia now. I have no idea about the current quality. The older stuff is very nice, indeed.
If we want to do a deep dive here, we can look at how the lines between AM and OEM are becoming blurred with replacement kits for older saws. Husky makes most of their own kits it Sweden for the current saws.
In Husky land.....272 top ends are now made by Kolbenschmidt Brazil. Still a nice looking kit, but not quite a Mahle. 372 kits at the time we retired were Gilardoni and really looked like a down grade from the Mahle. It more or less LOOKED like an AM kit, but sure wasn't priced like one
At that point, the picture is getting cloudy, isn't it?
Let's factor in the reality that we are discussing rebuilding saws that are 20-30 or more Years old. A 40 or 50 dollar AM kit to keep a saw in service is about the cost of a new bar. These kits at these prices keep plenty of saws on the wood pile and off the scrap pile. ffwave
My thoughts on cost of repairs. Or the value of the repair. It is not if the dollar amount exceeds the value of the saw, but will I get that dollar value out of the saw from use. So, putting $100.00 into a $100.00 saw to some may seem like a waste of money, but to me if I get a minimum of 10 tanks of fuel through that saw, then it paid for itself. Anything above that is bonus time. Avoiding a bad discission like buying a poorly made part can really change the outcome. Quality is very important. If I take care of it and maintain the saw, I will surely get more than that from my investment. On top of that I enjoy working on them. Now if I was using the saw for a business, lawn care, tree service or hired help, then old saws make no sense. I would not want the down time. For me I'm on my own and if needed I set the troubled saw down and grab the next one.
I visited the Northwoods Saw web site. Lots of good stuff.
Quote from: DHansen on April 17, 2025, 08:58:02 PMMy thoughts on cost of repairs. Or the value of the repair. It is not if the dollar amount exceeds the value of the saw, but will I get that dollar value out of the saw from use. So, putting $100.00 into a $100.00 saw to some may seem like a waste of money, but to me if I get a minimum of 10 tanks of fuel through that saw, then it paid for itself. Anything above that is bonus time. Avoiding a bad discission like buying a poorly made part can really change the outcome. Quality is very important. If I take care of it and maintain the saw, I will surely get more than that from my investment. On top of that I enjoy working on them. Now if I was using the saw for a business, lawn care, tree service or hired help, then old saws make no sense. I would not want the down time. For me I'm on my own and if needed I set the troubled saw down and grab the next one.
I like your logic, Dave. Makes perfect sense for enthusiasts like most of us are on here, who tend to have more saws than we really "need". (Did I just say that? :uhoh:) Most pros have a different set of criteria to consider.
Quote from: Spike60 on April 17, 2025, 08:44:27 PMIf we want to do a deep dive here, we can look at how the lines between AM and OEM are becoming blurred with replacement kits for older saws. Husky makes most of their own kits it Sweden for the current saws.
In Husky land.....272 top ends are now made by Kolbenschmidt Brazil. Still a nice looking kit, but not quite a Mahle. 372 kits at the time we retired were Gilardoni and really looked like a down grade from the Mahle. It more or less LOOKED like an AM kit, but sure wasn't priced like one
At that point, the picture is getting cloudy, isn't it?
Let's factor in the reality that we are discussing rebuilding saws that are 20-30 or more Years old. A 40 or 50 dollar AM kit to keep a saw in service is about the cost of a new bar. These kits at these prices keep plenty of saws on the wood pile and off the scrap pile. ffwave
Noticed the same thing with the 55 family, Spike. The plating got thinner towards the end of production, even on the Mahle top ends. Our cylinder-saving rate takes a hit on these saws when blown-up. That's taking into consideration that the typical 51/55 user in our area doesn't know the early-warning signs and so merrily keeps it pinned to the point of nuking the top end. Deep-six scoring results and it's probably 50/50 on saving the cylinder. For a $300 CAD saw (in our neck of the woods, anyways), a 4+ star $50 Scamazon kit gets them going again, with plating that is not far off the late-OEM level. I call that a win!