MS260 scored cyclinder repair and starting kids on chan saws ?s

[Trapper_Pete]

I bought the saw new in 2007 , have run it since , always run good oil mixed to the directions on the bottle with non ethanol gas but I had a fuel line go bad at 9 1/2 years and the saw was apparently sucking air and over heated when that first happened about 3 weeks ago I took it to the local saw shop he isn't a stihl dealer but a good guy and he figured out it was the fuel line , replaced fuel line and filter also changed the plug for the first time in 9 1/2 years hey it was running fine feed t good gas and keep cutting I estimated my hours on the saw at around 750
at this point he measured my compression at 120 pounds
I took it out cutting again and it ran about 15 minutes of good cutting then died again took it back this time I have 90 pounds of compression , well I ran it one more time again about 15 minutes and it was done

my compression tester and T27 torx that will fit in the jug holes should arrive today

I will post a pic of the cylinder when they do and I can test the compression and pull the jug

I am contemplating do I go with a new NWP jug and piston kit 95 dollars + 15 for a new needle bearing for the cylinder pin

or do I buy a flex hone , oil , a new NWP or meteor piston and hone the original cylinder this ends up adding up rather quick but saves a few dollars 24 for the hone + 10 for hone oil + gasket kit + new cylinder+ new bearing 15

or tell me the other options please

what else should I be replacing as long as it is open this far?

what gets me a strong new life from this saw that can get me another decade or so of use?

I don't need anything other than a dependable running saw that I can keep 16-18 inches of my 20 inch bar in wood and cutting so that I can keep us in fire wood most of our heat for the winter by now I am cutting on 2017 and fire wood for sale not very high volume but some cash to buy new equipment with as I use it up, I also trade some cutting for meat with a farm I cut for so my saw is my heat / grocery getter. even though I have a day job.

I got a new saw from my local saw shop so I could keep cutting a Jonsered 2255 but I want both running my current backup saw is a little pulan pro 210 and is kind of a joke but it was free the previous owner left ethanol gas in it I cleaned it out and it runs.

my son is 13 and keeps asking when he can run a saw and we can put his sister(11) on the splitter he started running the splitter at 11 , but I am a little Leary to put him on a saw just yet , when I do it will be on a sawbuck and with some 6 - 8 inch stuff to get him started but I am probably only a year or two away from him running this 260 I keep reminding him when your running a saw if your nose itches you got to let it itch or shut down the saw there is no cutting and itching at the same time.

so if anyone has advice about how to start kids running saws I think I started about 14 maybe not the best way but I figured it out I started on a home lite then an 029 and by the time I was 16 was running a 044 on the farm I worked on.

 

[Trapper_Pete]

the compression tester came but not the t27 wrench , I also realized I really should pressure and vacuum test the saw before I tear it down to make sure I have no other air leaks

I should have the pressure and vacuum tester by Friday and check for leaks.

 

[Matt_Ellerbee]

Once the T27 comes in,pull the muffler and plug,get a light and look at the cylinder and piston. Hopefully it's not scored too bad = saves you money. If it is,post some pics. You might can get by with a acid wash and new piston/rings. And of course fixing any air leaks while you got it torn down.

I was prob 10-12 when I ran my first saw. That was after years of running splitter and dragging limbs for dad. Teach them respect for the saw and to be focused 100% on it while running.

 

[Trapper_Pete]

I have 2 different T27 torx one on a scrench or maybe if it is a torx it is a torench but it will not fit down the jug holes the other is a socket 1/4 inch drive also a no go on jug holes so I am still waiting on the wrench but in the mean time I checked the cylinder compression and have 80psi and I cut bike inner tube gaskets and fitted them under the muffler and carb.
both the torx and the pressure / vacuum pump should be here tomorrow so that I can test for leaks and then remove the jug


I can see the scoring on the cylinder through the spark plug hole and I borrowed a 5.5mm camera from my brother it fits in the exhaust you can run it through the intake you can see under the cylinder it only looks scored on the exhaust side above the exhaust port from what I can see

the camera is only about 20 dollars and would be well worth taking on a used saw buying trip , hey just let me take the plug out to check and then camera in and you can look around inside as the camera has it's own led lighting and plugs right into my phone

what type of acid do yo use if acid washing a cylinder?

I really wish I had stopped trying to make this run when it first run into the problem but I ran it after the gas line was replaced and again one more time after that

when the gas line was replaced the shop said 120psi on the cylinder then the next time 90 now 80 had I stopped sooner it might have meant less damage, but I just wanted the saw to run so I could get back out cutting

 

[Trapper_Pete]

today I pressure tested and vacuum tested the saw the bike inner tube gaskets worked well

pump up to 7 psi and wait it held 3 minutes without moving

pump down to 6 in HG set timer 3 minutes no change

the driver came today I should have the jug off this evening after I have to go to parent teacher conferences and talkl with the gym teacher who is messing up my daughters perfect GPA

 

[Matt_Ellerbee]

Judging by that pic,you need a cylinder. Pretty cool camera too.

 

[Rockjock]

Since the pistons are so cheap in the US and most times you can clean up a cylinder I would go the OEM route. New lines, intake boot and seals while you are at it and then you have a reliable saw once again.

 

[Trapper_Pete]

I took the jug off , here are the pics


the intake side is smooth and the exhaust side around and above the exhaust port is not smooth but not very deep

or maybe it is raised?
to acid or not to acid to hone or not to hone ?

looking at the piston I ran out of rings on the exhaust side with plenty left on the intake side

 

[Mad Professor]

Running quite rich. Look at buildup in ex port. Some of that may be carbon scoring. Got a picture of the piston?

Always worth trying to clean up the OEM jug, if it does get a OEM piston. If not I'd look for a good used OEM 026/260 jug, note that they are 44 or 44.7 mm dia., get correct piston.

Get a stihl gasket set with seals. Put in the seals even though it pressure/vac tested O.K. PITA to do 026 seals, some dealers will do seals cheap if you bring them a clean stripped saw.

Consider a MM and an adjustable carb if yours does not have a Hi screw.

 

[Trapper_Pete]

the carb has a H adjustment , the muffler is stock

 

[trappermike]

By looking at the cylinder and piston it was running an extremely lean fuel/air ratio,it looks to me like a lot of melted aluminum. When you re-asseble the saw you must be sure that the entire fuel system and carb are checked for any problems or your next pist. and cyl. assembly will look just like that one fairly soon.
Ceck the fuel tank vent,fuel filter,fuel line,impulse hose,carb to cyl. bubber boot,and the carb should be cleaned carefully and a new complete kit put in.The high speed screw must be adjusted correctly most of all.

 

[jr27236]

Running quite rich. Look at buildup in ex port. Some of that may be carbon scoring. Got a picture of the piston?

Always worth trying to clean up the OEM jug, if it does get a OEM piston. If not I'd look for a good used OEM 026/260 jug, note that they are 44 or 44.7 mm dia., get correct piston.

Get a stihl gasket set with seals. Put in the seals even though it pressure/vac tested O.K. PITA to do 026 seals, some dealers will do seals cheap if you bring them a clean stripped saw.

Consider a MM and an adjustable carb if yours does not have a Hi screw.

Quite rich??? Thats one of the cleanest cylinder and pistons I have seen, an obvious lean condition or straight gassed. Thats the first thing I noticed in the pictures. The top of the cylinder looks like it just came out of the box.

 

[trappermike]

It even looks like melted alum. in the exhaust port,and the spark plug is too white from heat,no trace of oil on it...
You might as well try to save the cylinder,you have nothing to lose. I like to wipe out the cyl. first with some degreaser,like laquer thinner or other things,then get some muriatic acid from a hardware store. I like to cut some 2" square pieces of rag and dip them into the acid with some needlenose pliers(Wear a face shield and proper gloves,also when the acid hits the aluminum it creates some very powerful fumes,keep back,do in a well ventilated area.) then apply the acid to the areas where you see alum. on the cyl. bore. I like to rub it in and leave a tiny puddle over thick deposits. Keep rubbing the spots from time to time to tell when most of the alum. is removed,be careful doing this too long or you can eat thru the plating and cause pits where the plating was gouged from siezure damage. Finally wash the cyl. in some solvent and give a short go with the ball hone just enough to clean up the bore and put a cross hatch on it,be careful not to hone too much or you can wear thru the cyl. plating again.Check the chamfer on the ports,if you want to touch them up or improve them now is a good time. Slight remaining imperfections below the exhaust port need not be worried about too much,no compression happening there...

 

[jr27236]

It even looks like melted alum. in the exhaust port,and the spark plug is too white from heat,no trace of oil on it...
You might as well try to save the cylinder,you have nothing to lose. I like to wipe out the cyl. first with some degreaser,like laquer thinner or other things,then get some muriatic acid from a hardware store. I like to cut some 2" square pieces of rag and dip them into the acid with some needlenose pliers(Wear a face shield and proper gloves,also when the acid hits the aluminum it creates some very powerful fumes,keep back,do in a well ventilated area.) then apply the acid to the areas where you see alum. on the cyl. bore. I like to rub it in and leave a tiny puddle over thick deposits. Keep rubbing the spots from time to time to tell when most of the alum. is removed,be careful doing this too long or you can eat thru the plating and cause pits where the plating was gouged from siezure damage. Finally wash the cyl. in some solvent and give a short go with the ball hone just enough to clean up the bore and put a cross hatch on it,be careful not to hone too much or you can wear thru the cyl. plating again.Check the chamfer on the ports,if you want to touch them up or improve them now is a good time. Slight remaining imperfections below the exhaust port need not be worried about too much,no compression happening there...

I 2nd the acid technique, but you have to be careful with it. I would first go with the acid on a Q-tip taking your time is key and watch your progress closely, once you have most of it off then go with 400-600 grit emery paper and keep working at until the aluminum is off the nickasil. If you keep at the acid and you did damage the Nikasil coating with the initial problem the acid will eat the groove out that has been filled with aluminum and allow compression to leak past ( I have done this myself unfortunately). This saw has time on it and your son will get many more years out of it by cleaning up the cylinder and tossing in a Meteor Brand Piston.

 

[Mad Professor]

Quite rich??? Thats one of the cleanest cylinder and pistons I have seen, an obvious lean condition or straight gassed. Thats the first thing I noticed in the pictures. The top of the cylinder looks like it just came out of the box.

Yes was ran rich a long time. Look at the gunk buildup inside the exhaust port. You can also see some carbon scores on the ex side of the piston (black). Probably not what killed it, but not good.

It does look like straight gassed or a real bad air leak finally did it in.

 

[Trapper_Pete]

Rich then lean very near the end would be a fair assessment

I bought the saw new from a dealer in June 2007 I have been the only one to use and I am very good about my mixed gas only 91 octane Ethanol free with Stihl oil in the past two years I did run some Johnsered oil and Efco oil as my local saw shop stocks those but still good quality oil always mixed at the label directions 1 bottle oil one gallon gas or one bottle of oil and 2.5 gallons of gas when I went to a larger can I only have mixed gas around the house because I run the lawn mower and log splitter on it also.

but about 30-40 minutes of run time from the end for that piston , I had to replace the fuel line as it failed , what I don't know is how long the fuel line was supplying enough gas to run but not lube well

the saw has about 750 hours on it in the 9 years I have had it

it ran the same plug for 9 years with no trouble and had 2 new plugs in the last 30-40 minutes of run time

knowing what I know now had I run the camera in the spark plug hole after the fuel line issue , or inspected through the exhaust port I probably could have saved the larger repair and just done rings or rings and piston but it started right up and ran after the gas line and new plug it idled well , so I ran it and it made it about 15-20 minutes of cutting that was 6-7 cuts in the log I was working on at the time. new plug and it went about 6 cuts again

I guess I figured if it started and ran and idled well and cut like normal with the hole bar in the log strong for a few cuts it was good to go so I ran it

 

[Mad Professor]

Try cleaning up the cylinder. You might get lucky and find that it's all aluminum transfer and the nickasil underneath is stihl O.K.

 

[Trapper_Pete]

I went with the NWP kit from bailey's online I weighed out my options with a piston and rings kit , hone and hone oil I was almost to the kit with the new cylinder

I vacuum and pressure tested the saw before dis-assembly and after re-assembly all checks out.

the saw runs like new now , it went together easy

I let it idle for a good while then cut a few pieces of wood then let it idle for most of the rest of the first tank of gas then I took it cutting for the second tank of fuel with a fresh chain it cut well just like I had remembered

just not as fast as my new saw

I might have gotten a little spoiled with my new saw while I was working on this the new saw is bigger

but this is a great backups saw and will probably use it for more of the smaller stuff it seemed like it would be a waste to scrap it it should have a lot of life left in it with this new top end

 

[Red97]

I could use that old jug if you aren't planning on keeping it.

Where bouts in wi you located ?

 

[blsnelling]

I'm guessing this saw was tuned way too lean after the fuel line repair.