Need help stihl 056av super

[Acts16:30-31]

I havea stihl 056AV super and i'm told that it has lost its compression, but the thing is that it will crank up and run. When i throttle the saw it takes between 5 and 10 seconds to get up to full speed. Also it won't idle for more than a minute or so. Last time i ran it i used what i thought was a quality 2-cylce mix turns out i was wrong i completely burned up a MS250 it has absolutely no compression. The 056 i ran right after using the 250 not knowing at the time that the 250 was burnt up. THe 056 ran for about 5min on the bad gas mix then it got hot and quit and i was not able to get her started again. I took it to a guy who made some adjustments on the carb and was able to get her to crank up he also changed out the fuel. but like i said before it would not idle for more than a minute or so. My question is what could be the problem if it does need a new clyinder/piston where can i go about finding a replacement? If not that where should i look first? Any help would be greatly appreciated

 

[GASoline71]

Moved to chainsaw forum...

Gary

 

[fearofpavement]

Step one:
Remove muffler and spark plug and look at the piston and inside of the cylinder while moving the piston up and down. Report back with your findings.

 

[Acts16:30-31]

Step one:
Remove muffler and spark plug and look at the piston and inside of the cylinder while moving the piston up and down. Report back with your findings.

Well I did like you said, not knowing what to look for I'll give this a shot. The piston had two rings they were polished the piston itself had some polished streaks on it, but mostly was a white color. From what I could see the inside cylinder walls were grey didnt notice any discoloration. Had the same look as cast metal.

 

[axlr8]

pictures???

 

[Acts16:30-31]

View attachment 255113View attachment 255114
here are some pics

 

[tomdcoker]

You have scored the piston. To put it back in good shape you will need a piston and rings for sure. It is possible that the cylinder will clean up with acid and sand paper. If you decide to do that do some research on the site on rebuilding a saw. Tom PS I like your user name.

 

[Ifishsum]

Doesn't look too bad just from those photos, good chance it would just need a new piston/rings and a cylinder cleanup. Might as well pull the cylinder and get a real good look. I rebuilt my brother's 045AVS this spring and it was much worse that yours looks. Luckily I was able to clean up his cylinder because even a used OEM 54mm jug was way above his budget if it could be found (which should also be the size of yours). Even an aftermarket 54mm piston kit took some looking to find, but I eventually got one from Northwood Saw (site sponsor) that has worked out very well so far. Had to hit the bay to find a base gasket.

Good luck with it, it's a strong saw when running good.

 

[Acts16:30-31]

First off thanks to everyone for the input. I was able to get the jug off this afternoon and got a real good look at the P/C. The piston is definitely scored. I can't be sure but i think that the cylinder is in good shape. I took some pics so you experts can tell me for sure. Anyways i have some acid and scotch brite to clean it up with. I also found something else while taking things apart. I believe it is the fuel line going to the underside of the carb. That line has a crack in it. From the pics that i took it looks like a hole but if you seperate it. It pulls opens up to about an 1/4 inch opening. I am wondering if that may have been my problem all along. Just wondering i'll defer to your expert opinions. anyways here are some pics i appreciate all feedback
View attachment 255275View attachment 255276View attachment 255277View attachment 255278View attachment 255275

 

[blsnelling]

That is the impulse hose. Yes, a hole in that could have caused it to run lean and score. I do believe that you could polish up your parts and put it back together.

 

[sefh3]

By the looks of it you can save the cylinder. Muratic acid should do the trick. The line is your impulse line. I'm sure this is causing your idle issues and your scoring on the piston.

 

[blsnelling]

 

[Acts16:30-31]

just to clarify can i re use the piston or do i need to get a new one. If so do i get aftermarket, OEM or is there a difference?

 

[blsnelling]

Honestly, I believe it would be perfectly fine if you polished it all up real good. It's not like you're looking to sell it to an unsuspecting buyer.

 

[sefh3]

I don't remember if there are aftermarket pistons out there for this saw. You can try Northwoods or Baileys to see what they have for aftermarket. I'm sure an OEM is pricey.

 

[Acts16:30-31]

Question what is the purpose of an impulse line

 

[tomdcoker]

Do not breathe the fumes from the acid. This is best done in an open area and with a fan blowing the fumes away from you. While you have the saw this for down it would be a good time to pressure test it for a leaking seal. If you do not have the equipment check with your local saw or small engine dealer. If you will prepare the saw they should do this for a small price of for free if you are a good customer. Tom

 

[tomdcoker]

Question what is the purpose of an impulse line

The impluse makes the carb. pump fuel. Tom

 

[Acts16:30-31]

ok thanks for the tip i think i'll do that. Something else i was wondering about i notice when i was running it that it was putting out lots of oil i let it run for a minute or so and there are several ounces of oil on the ground or underneath the saw does that sound right?

 

[sefh3]

I'm sure you have an adjustable oiler on that saw. It more than likely is set at the max.