sthil 026 rebuild gone wrong

[pioneerguy600]

I’m with this guy here. Will take you all of 5 min and cost nothing.

Until you experience this yourself, you wouldn’t think of checking it.

Pretty much the only thing that’s missing in the equation for a running saw, fuel/compression/spark (at the right time).

I’ve also had ported husky saws hit the plug ground strap, close the spark gap, and behave the same way.

I believe fuel to the cylinder was the problem with the OP`s saw, I follow a system I have always used on chainsaw and small engines and it gets me results faster than guessing. Spark first, fuel next even if I have to manually add it, if no hit or run then I might change the plug especially if it looks coated with carbon. I can tell at least 90% of the time if there is enough compression without a tester and can feel the internals of the engine while slowly pulling the cord out. A saw engine will start with fuel introduced even if the crank seals are shot or the impulse line is off, a saw that starts and won`t pull fuel is another problem area that will be checked with a Vac- pressure test.Next would be checking timing,pulling flywheel but only after trying the first 2 things I posted.

 

[mobilemech13]

A big problem with carbs that have sat with fuel in them for a long time, if it's ethanol free fuel, it's good for about a year to sit in the tank and carb, if it's ethanol fuel even mixed with good oil, it starts to go bad in about 3 weeks. The ethanol is destructive to the adhesive on the welch plugs and there no glue to fix this once it come loose, rendering the carb worthless. Getting a saw from anywhere that it has sat for unknown time, I'd get a new carb, check the flywheel for timing and do a vac Presure test done on the case. There are a couple reasons for a scored cylinder, piston. Strait gas, air leak, bad carb. It may run while it's destroying the new piston and cylinder

 

[PogoInTheWoods]

The previous owner must have one helluva memory to remember the saw was straight gassed after it was sitting in his attic for 3 or 4 years..., unless he straight gassed it himself or it had a tag on it. One way to tell (typically) is the piston will be scored all the way around (to some extent) instead of just on the exhaust side. If the one you removed was only scored on the exhaust side it may well have been due to a simple lean condition from an air leak.

I agree that a saw will still pop and even run with bad seals. And the 024/026 is notorious for the flywheel side seal going bad and toasting top ends..., a testament to how long a saw will actually run with a bad seal. I'd pull the flywheel and take a close look at that seal while you're also dbl checking the key for correct timing alignment..., just because Harley said to if nothing else. (Hi, Harley.) Better yet as suggested, do a vacuum/pressure test on the saw to ensure there aren't any leaks from the case or the intake components..., or risk burning it up again faster than it took you to get the old top end off in the first place.

Great little saws, but are finicky to tune on occasion. Just don't waste too much time pissing up a rope trying to tune out an air leak (if it has one) once you get a new kit in that carb. A vac/pressure test will tell the tale.

Good luck with it.

And on a side note, I just recently rebuilt a super nice early 026 that was such a nasty mess I didn't even know what it was when I got it. I still need the early air filter (short) and air box cover if anyone happens to have either or both to spare. I'm hoping for a nice cover as the saw cleaned up surprisingly well and I'd like a fairly close match if possible. This one will be a keeper. TIA for any help there.

 

[drf255]

I believe fuel to the cylinder was the problem with the OP`s saw, I follow a system I have always used on chainsaw and small engines and it gets me results faster than guessing. Spark first, fuel next even if I have to manually add it, if no hit or run then I might change the plug especially if it looks coated with carbon. I can tell at least 90% of the time if there is enough compression without a tester and can feel the internals of the engine while slowly pulling the cord out. A saw engine will start with fuel introduced even if the crank seals are shot or the impulse line is off, a saw that starts and won`t pull fuel is another problem area that will be checked with a Vac- pressure test.Next would be checking timing,pulling flywheel but only after trying the first 2 things I posted.

No need to pull flywheel. Just see where magnets line up at TDC.

 

[rupedoggy]

Hey you block heads the saw idles! It would not do this if your flywheel key was sheared. Check the small screen in the carb and the filter in the tank. Not getting enough fuel. Maybe stiff diaphram in the carb.

 

[muddstopper]

Well, a little update, I took saw to shop today with plans to let them do a vacuum test and possibly just buy a carb. Told the mechanic what the saw was doing and I thought it wasnt getting any gas. He pulled the breather, sprayed a bit of some sort of starter fluid,, dang I meant to see what the fluid was, anyways, saw cranked first pull, he adjusted the carb and let it run for a few minutes. Saw will fire right up. I asked what he did and he just said he sweet talked it. What ever, but the saw did crank and run so who am I to argue. Anyways I figure I must have probably flooded it with to much gas or something.. Dont know what I did or what the problem was, but I took the saw to my brother and gave it to him to replace the one he had stolen.

 

[muddstopper]

Maybe I should tell exactly what I did to try and get the saw to run. After replacing topend, I just added gas to tank. No crank. On the suggestionto add some oil to the cyl, I removed plug and just put some 2cyl oil in plug hole. I then let this set while I removed the carb and took it apart. After replaceing carb, I pulled the starter a few times to clear out excess oil from cyl and then replaced plug. Then poured gas mix in carb. Saw hit and tried to run for about a minute. Poured more gas n carb and saw cranked and sputtered. More gas in carb and then wore my arm out trying to crank. Didnt try to crank the saw today before taking to shop, I had it in my mind I had a vacuum leak and it wasnt getting pressure at the pulse line. I guess its alright to be wrong a time or two. Got to learn that sweet talking trick, calling a saw a &@$%#^@ piece of $(^* doesnt seem to work.

 

[grizz55chev]

If you poured gas in the carb and left the choke on while trying to crank, there’s no way it would run. To clear a flooded saw, leave the choke off, set the saw on high idle or full throttle, and crank till it fires, usually 4 or 5 pulls will do it. Glad it’s a runner.

 

[user 122190]

The one time I could not get a saw to run was when I was trying to sell it. Pulled, and pulled and pulled. New owner was looking like he was about to leave. I quickly pulled the plug, bone dry. Checked the gas, no gas. I had ran the saw the day before and it ran perfectly. It must have run out of gas just as I shut it off. FWIW, it is usually something too simple to bother checking.

 

[pioneerguy600]

No need to pull flywheel. Just see where magnets line up at TDC.

Are you kidding, how many newbies could even find TDC accurately enough to tell where the magnets really are, you and I can and the rest of the well experienced. I have tutored more than a few newbies on setting up degree wheels and it would take them more than hour to accurately find TDC and then compare where the magnets are sitting, they could be off as little as 1/4" and not be detected as a timing jump. Pulling the flywheel is the preferred method of checking a sheared key by anyone that has not worked these saws for port timing.

 

[drf255]

True Professor.

 

[pioneerguy600]

True Professor.

LOL

 

[HarleyT]

LOL.
Many of our veterans/builders here cannot seem to pull a clutch or flywheel without farking up the saw!!!!

 

[muddstopper]

Are you kidding, how many newbies could even find TDC accurately enough to tell where the magnets really are, you and I can and the rest of the well experienced. I have tutored more than a few newbies on setting up degree wheels and it would take them more than hour to accurately find TDC and then compare where the magnets are sitting, they could be off as little as 1/4" and not be detected as a timing jump. Pulling the flywheel is the preferred method of checking a sheared key by anyone that has not worked these saws for port timing.

Your arm aint getting sore from patting yourself on the back is it. And what in the heck is so hard about finding TDC, you dont need a degree wheel to do anything that simple. A positive stop in the plug hole and a piece of wire for a pointer and finding TDC wouldnt take a full minute. Now if your talking port timing, or changing spark timing, then a degree wheel is pretty handy, but on a stock rebuild not something one would be checking anyways.

 

[pioneerguy600]

Your arm aint getting sore from patting yourself on the back is it. And what in the heck is so hard about finding TDC, you dont need a degree wheel to do anything that simple. A positive stop in the plug hole and a piece of wire for a pointer and finding TDC wouldnt take a full minute. Now if your talking port timing, or changing spark timing, then a degree wheel is pretty handy, but on a stock rebuild not something one would be checking anyways.

The reply was meant for the person who I quoted, you have no idea.

 

[muddstopper]

The reply was meant for the person who I quoted, you have no idea.

enuf said

 

[Jasonrkba]

Does sound like maybe it was flooded or maybe something in the carb that was clogged finally broke free. Either way glad you got it running.

 

[muddstopper]

Built 2 more saws yesterday. My Grand Daughters boyfriend had his saw stolen out of the back of his truck. He has been out of work and selling firewood to make ends meet. I told him I had a bunch of junk piled up in the basement, lets sort threw it and see what we can come up with. I had a old husky 50 I had put a 51 top end on and changed the carb over so could add a pull choke. It needed finishing up so we got it runnng and I gave it to him. I also had a bunch of piece saws, mostly 51's and some closed port 55's and I had a new oem 55 open port topend. I had to mix and match parts, but I ended up with a 53cc 55, on a 51 case. I didnt have a new gasline and I need a new sprocket and I got to put a cord in it, but I'll fix that when the stores open after while. I had bought a box full of husky parts about a year ago. I Have used the pieces and been able to build or fix 4 different saws. Now I got to decide what pieces of the left overs I will throw away and what I will keep.

 

[drf255]

LOL

My point was that a small discepancy will usually still allow a saw to run, albeit poorly.

Pulling plug and startercover, and then looking at where magnets hit and pison reaches top is a quick reference that requires no special tools. It won’t work 100$, but there is no puller or special tool needed.

I agree, pulling the flywheel is the only accurate way to tell.

 

[pioneerguy600]

My point was that a small discepancy will usually still allow a saw to run, albeit poorly.

Pulling plug and startercover, and then looking at where magnets hit and pison reaches top is a quick reference that requires no special tools. It won’t work 100$, but there is no puller or special tool needed.

I agree, pulling the flywheel is the only accurate way to tell.

My post was really about the accuracy aspect and I may have laughed too hard and had tears in my eyes when I posted. I have tried the magnet alignment at TDC and it works if I put a piston stop in the sparkplug hole and fiddle with it til the piston barely kisses the stop at TDC, the magnets are still not perfectly aligned but close enough to make the engine run or pop as some say. My initial thought was that few new comers that come on here and ask for help would have either a piston stop or any other accurate means of finding TDC accurately. I watched several fellows fiddle with screwdrivers inserted into the cylinder trying to find TDC but since the sparkplug hole is not straight up nor centered in the cylinder bore the screwdriver gets pushed up but gets further sideways as the piston nears TDC, they just could not tell where TDC was with any accuracy. I showed each of them a piston stop I had made that would work but the common ones are too long, the threads would be completely out of the sparkplug hole before the piston reached TDC rendering them not easy for a beginner to use for finding such. Yes they can be used with a degree wheel but few beginners have one of them either.