Advice on used Stihl 260 Pro

grb5043 · August 26, 2020, 07:55:36 AM

Hi, I'm new to the forum. I recently purchased a non-running Stihl 260 Pro for $50. I know that buying a used saw is always a gamble but for the price I thought I couldn't lose. Upon getting it home I took the muffler off and to my dismay found a scored piston. I checked the compression and it was only 90 psi. I couldn't find any official compression numbers but a youtube video I found said it should be around 180 psi after a rebuild. The guy in the video said 140 psi is okay and anything under 120 psi he would be worried about. I also pulled the spark plug and confirmed that it was indeed making a spark.

My dad on the other hand felt that at 90 psi and it making a spark, that it should run (perhaps not at peak performance, but still run). We drained the gas and put fresh gas with Stihl synthetic oil mix. Then we sprayed some starter fluid into the carb and started cranking and it immediately almost started. After several minutes of pulling it did start and runs well at full throttle. I then set to cutting up some wood to give it an "Italian tune-up" as my dad suggested. It seems to run pretty well, I'm going to get a new spark plug and air filter, but beyond that should I just leave well enough alone? I heard something once along the lines of "if it's not broken, fix it until it is." I was considering replacing the cylinder and piston but now I don't think I need to. Thoughts by more experienced people?

Al_Smith · August 26, 2020, 09:18:46 AM

The 026/260 had three different mufflers ,one was highly restrictive and thus often caused an over heating condition which eventually would scorch the piston .
So now comes the question what to do .If it runs leave it alone .If it doesn't run well enough you could sand out the piston install new rings and that might get it .You could also use an aftermarket piston at about $35 a pop.You could buy a complete OEM top end too but you'd have a lot of money in it .
BTW using starting fluid can often have bad results .
FWIW I got an 024 I got from a dealers "dead pile" for 50 bucks . It had a slightly scorched piston .All I did was cut the baffles out of the muffler and ran it ,nothing more .That was 7-8 years ago and I've never had a problem .Actually it's a pretty nice little saw .

grb5043 · August 26, 2020, 09:28:34 AM

Thanks for the reply. It seems to be running well enough for my purposes so I'll leave the engine alone. Is there a way I can tell if the muffler on it is the highly restrictive type? If it is should I cut the baffles out? If so, is that pretty straight forward? Also why does using starting fluid often have bad results?

doc henderson · August 26, 2020, 09:33:56 AM

the starting fluid is pure dry fuel so if overused, it will cleanse the cylinder of oil and promote engine failure. some will use WD 40 instead. Prob a new carb or rebuild of that, to help with idle. can also run some carb cleaner in the old one and see if that helps. most of the carbs that have rubber diaphragms do not last forever. this saw is well out of any warranty, so you can do what ever to the muffler and no one can say much.

ZeroJunk · August 26, 2020, 09:59:48 AM

If it comes a time that it needs to be rebuilt I would just put a piston in it. You can take the cylinder off and clean it really well and you willl be able to see the aluminum that is melted on to it. The nikasil underneath is very hard. You can take a small piece of maybe 200 grit sand paper with your finger and sand it off. Sometimes muratic acid that you can buy at Lowes or HD and a Q tip will help melt the aluminum.

If you use an aftermarket piston either use OEM cir clips or take a pair of cutters and cut the tabs off. I think Meteor quit furnishing circlips with tabs. The y break from metal fatigue eventually.

grb5043 · August 26, 2020, 10:30:26 AM

Quote from: doc henderson on August 26, 2020, 09:33:56 AM
the starting fluid is pure dry fuel so if overused, it will cleanse the cylinder of oil and promote engine failure. some will use WD 40 instead. Prob a new carb or rebuild of that, to help with idle. can also run some carb cleaner in the old one and see if that helps. most of the carbs that have rubber diaphragms do not last forever. this saw is well out of any warranty, so you can do what ever to the muffler and no one can say much.

That makes sense about the starter fluid. Prior to reading this response I asked my dad about it and he said he recognized the potential danger but felt we didn't use that much nor have much to lose.
So you would put a new carb or rebuild it before simply adjusting it in its current state? I haven't even tried adjusting it yet. After running it wide open for a little while yesterday cutting it did idle but eventually died after maybe 30 seconds.

sawguy21 · August 26, 2020, 10:58:28 AM

Starting fluid is a death sentence for two stroke engines, it also dries the crank seals so they shrink and crack. The saw is over 20 years old, run it till it drops.

Al_Smith · August 26, 2020, 11:36:22 AM

WD -40 used to work as a starting fluid when they used propane as a propellant .I'm not certain if that is used today or not .Usually just some mix gas in a squeeze bottle is what most use --sparingly by the way .Too much will flood it and on some saws try to kick back and attempt to pull your fingers out of the sockets .Even a little 026 can come back hard enough to be painful .A large saw will attempt to pull you through the rewind assembly .

sawguy21 · August 26, 2020, 12:25:48 PM

Yup! :D

doc henderson · August 26, 2020, 01:27:41 PM

you can try to tune and adjust the carb. i would take it off and clean it. a carb kit can be the same price as a new carb. the carbs on chainsaw have a lot of rubber that breaks down, and small channels that may continue to dissolve the old varnish gummed up fuel if it sat for a while. I thought from the original post, it only ran ok at full throttle. If your goal is the most use for the least amount of time and money then there is that. if you can tune it and it runs and starts well, then good. if you want to run this thing for years, and not have trouble, or you continue to have trouble starting it, then check the price of a carb kit, vs new carburetor. If you take it off to spray it well, look at the rubber. if it is aged, and you take it apart, it may rip and then you are stuck replacing. hope it works out and you feel yo got a great saw for the price.

grb5043 · August 26, 2020, 01:47:13 PM

Quote from: doc henderson on August 26, 2020, 01:27:41 PM
you can try to tune and adjust the carb. i would take it off and clean it. a carb kit can be the same price as a new carb. the carbs on chainsaw have a lot of rubber that breaks down, and small channels that may continue to dissolve the old varnish gummed up fuel if it sat for a while. I thought from the original post, it only ran ok at full throttle. If your goal is the most use for the least amount of time and money then there is that. if you can tune it and it runs and starts well, then good. if you want to run this thing for years, and not have trouble, or you continue to have trouble starting it, then check the price of a carb kit, vs new carburetor. If you take it off to spray it well, look at the rubber. if it is aged, and you take it apart, it may rip and then you are stuck replacing. hope it works out and you feel yo got a great saw for the price.

Thanks for the reply and thanks to everyone for giving me advice.
It does run ok at full throttle. It only reliably starts on half choke though. My goal is use this for years so I'll look into the rebuild kit vs. new carburetor. Thoughts on OEM vs. aftermarket? Since I don't have a lot of money in it I was thinking OEM, unless its absurdly expensive. Also I was going to buy an OEM air filter but apparently they're $30 for this saw. I took apart and cleaned the one that came with it with low pressure air and then soap and water like I read in other threads. Is a new air filter worth it?

Al_Smith · August 26, 2020, 02:13:20 PM

Again there are a lot of options .You could go with an OEM carb from a dealer and have fortune in it .Generally speaking a so called cleaning won't work out well .I think it's a Walbro WT carb , a basic kit is under 10 dollars .
If you've never rebuilt a carb it's fairly easy .If you run into problems help is only a few mouse clips way .Walbro has a very good web site with just about everything you ever wanted to know about their carbs .It's not uncommon to have problems with the soft internal components of a cab to need renewed maybe every 5 or 6 years .The gasoline with a certain amount of high tech moonshine these days does a number on them .You just have to deal with it .

doc henderson · August 26, 2020, 02:31:59 PM

a new 261 cm is over 600 bucks, so i agree with putting some time and effort in. as well, the carb kit is more like maintenance as al said. it is prob due, esp. if the fuel went bad. did it smell like varnish? good luck

grb5043 · August 26, 2020, 04:49:13 PM

Quote from: doc henderson on August 26, 2020, 02:31:59 PM
a new 261 cm is over 600 bucks, so i agree with putting some time and effort in. as well, the carb kit is more like maintenance as al said. it is prob due, esp. if the fuel went bad. did it smell like varnish? good luck

I know I was looking at new 261 cm's the day before I saw this on craigslist. I was seriously considering buying one.
I have rebuilt carbs before on my on 1983 Honda Nighthawk. But after pricing a new OEM one and it being less than expected, I'm going to spring for a brand new one instead of the rebuild.
Modifying the muffler was mentioned earlier. Could someone give me some more information about that?

Al_Smith · August 26, 2020, 05:24:20 PM

I'm an outlaw according to some .I cut the entire baffle cage out,remove the spark screen and any divertors and cut the outlet to about 80 percent of the exhaust port .It gets louder but not that bad .All that's left when I get through is just a pressure can .

doc henderson · August 26, 2020, 06:16:35 PM

run it and take care of it. a pro saw is usually worth rebuilding I am told. i have never worn one out. My 046 mag still runs great after 30 years. you can send it off and have it ported and some other neat stuff. there are many (if not all) that know a lot more about that than I. nice chatting with you, and welcome!

grb5043 · August 26, 2020, 07:13:17 PM

I will and thanks again to everyone

sawguy21 · August 26, 2020, 08:37:35 PM

A carb o/h might buy you some time but with a scored piston you are putting a band-aid on a chest wound. Clean up the cylinder if it is salvageable, replace the piston and crankshaft seals if you want maximum performance. It is not expensive and you will have a great saw that with proper care will last for years.

grb5043 · August 27, 2020, 03:23:43 PM

Quote from: sawguy21 on August 26, 2020, 08:37:35 PM
A carb o/h might buy you some time but with a scored piston you are putting a band-aid on a chest wound. Clean up the cylinder if it is salvageable, replace the piston and crankshaft seals if you want maximum performance. It is not expensive and you will have a great saw that with proper care will last for years.

I know you're right about the carb work being a band-aid. If I did replace the piston (or maybe whole top end) and crankshaft seals would you use OEM parts or aftermarket?