I recently resurrected Dad's old Stihl 056,needed a big saw and found this to be adequate.Put new rings on the piston,scrapped the Bosch electronic ignition and put a points style ignition on it.It ran great for a few rounds of firewood,no problems.Then the engine quit on me one day,at an idle,and I couldn't get it to fire.After some troubleshooting,I discovered the flywheel had jumped the key on the crankshaft and was out a few degrees...no problem,I got a key from the hardware store,filed it down a bit,fit it onto the crankshaft,re attached the flywheel and got a nice blue spark.Tried starting the saw...it fired once and nothing.Pulled it until I was tired(out of character for this saw,used to fire in 2 pulls cold).....nothing.Ok,so it must be a compression issue.I looked into the exhaust port and saw a little scoring on the piston...so I got an aftermarket 54mm piston and rings,put that in,here we go should be better than ever.Got it all together,pulled and pulled and pulled......nothing.Now I'm thinking cylinder,had checked it for ridges and hadn't felt any,but what else could it be?Crankshaft seals?I tested the compression at the spark plug port and got 105 psi(which is low,but I would think it should at least fire)So I have fuel in the cylinder,105lbs of compression,a spark that would electrocute a bull....and no explosions.Anyone have any ideas?Besides a dose of swap?I kind of like this saw but my husqvarna 55 rancher I've owned for 12 years,have run it over,dropped trees on it,left it out in the snowbank....and it starts in 2 pulls no matter what.I have yet to take it apart.
Stumped with my 056 Stihl
- Thread starter sawhawg
- Start date
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lcso10
ArboristSite Guru
The compression concerns me a little. The bigger thought is, is the spark you have getting there at the right time? Why did you go back to points?
It's pretty important to do a leak test after (and I personally think before as well) pulling a jug. Most of the time you pull a jug, it's to put a new part in, and it's good to ensure that you won't ruin that part.
How's your intake boot looking? You could be leaking there. I have one if you need it.
NORMZILLA44
Addicted to ArboristSite
Good point on the comp, low for sure almost none for that saw. Some go to points I hear due to electronic failure from heat I believe, and If I remember right next to impossible to find a replacement. O.P 056 is a great saw worth a complete rebuild if you ask me. Did you double check the points and gap? Not sure on the 56 but air gap?
homelitejim
Full of Scrap
+1 on the intake boot. Also check to make sure cylinder is on tight, I was having a similar problem with a 075 and found the cylinder bolts worked loose, torqued them down and got back the compression and it fired right up. It had good spark, fuel, but the low compression kept it from running.
An 056 with a new piston should be pulling 150 PSI minimum........Something's not right.
Before you pull it apart again, vacuum and pressure test it to be sure it's air tight.
Before you pull it apart again, vacuum and pressure test it to be sure it's air tight.
He says he just put rings in it, either way 105 PSI depending on the gage accurracy is borderline in whether it will fire or not with any consistency.
If he seized the rings that fast he has an air leak somewhere, bad gas, or tuned too lean.
Air leak or not, if the saw was revving to spec it shouldn't have burnt the piston.
cajunhillbilly
ArboristSite Operative
My first concern would be why it shaved off a key. Did it backfire before doing this? Sounds like the timing is off. If mine smoked two pistons (as I understand) I would be looking for a leak as others have said, must be a major one. Without a doubt for this saw no explosion at 105psi. with lighting for a spark. Yank it back down and let us know what you find. If you prefer that Husky you have over putting more money in that 056 I will gladly take it off your hands
Didn't smoke the second piston,never got it to fire after replacing the first.First piston measured 2.128,the second 2.134.Intake boot looks fine.How sensitive is the timing on these?If you are off a couple degrees,will it not at least pop?When I put the points in,I located the stator about halfway on the slots and it ran fine.It didn't backfire when it shaved the key.I went to points because the electronic ignition failed,I bought another bosch setup on fleabay,that one also failed,figured the points were a more reliable approach....had heard the electronic ignition could not stand the heat buildup under the flywheel.
Rupedoggys cynical read between the lines;
I left the flywheel nut too loose and sheared the key. I saw a little transfer on the piston/cylinder so got a new piston and honed the cylinder.
I left the flywheel nut too loose and sheared the key. I saw a little transfer on the piston/cylinder so got a new piston and honed the cylinder.
My bad, I didn't read closely enough that you did put a new piston in it. Are you sure about the accurracy of your compression tester ? Something is wrong there and a crankcase air leak will have nothing to do with a compression test .
You've got to watch out for those dyslexic pressure guages, shows
105# for one test, then 150# the next time!
cajunhillbilly
ArboristSite Operative
:dunno:
trappermike
ArboristSite Guru
When you installed the points ignition did you use the points flywheel too? That's a must.
Good to hear you got it running with good compression!:msp_thumbsup:
Good to hear you got it running with good compression!:msp_thumbsup:
You've got to watch out for those dyslexic pressure guages, shows
105# for one test, then 150# the next time!
Yeah,the second test I dumped a little 2 stroke down the cylinder....maybe the first go around the rings weren't seating properly,then they became happy with additional lubrication....a lesson learned.....I'm far from an expert,but I like working on my own stuff.I did use the points flywheel,the electronic flywheel is incompatible with the points stator,that is true.She's back to normal now,hopefully won't act up for awhile
I am glad you got her running I have had some tribulations myself as of late .I just put a p/c on a partner 5000 today and I put a few drops of two cycle oil in the plug hole and tilted the saw all aound to spread it around a little. I just feel better with a little lube in there on the first go.
After adding that little bit of oil,I could feel more compression on the rope,and when it fired it smoked that excess right up.I am running a richer mix,just a tad more than 3.2 oz per gallon,plus giving things a chance to seat and harden by starting the motor,letting it warm up,and shutting it down,not winding it up to max rpm.Hoping a little break-in will make a difference in the long run
I was just ribbing you, mine never seem to read the same everytime either.
Glad to see you got it going, those S056s are my favorite big wood saws.
