New piston or just a ring?

[Maine logger88]

I have noticed my 562 was losing power over the last couple months. I looked through the exhaust and noticed the piston had some scuffs on it so I pulled the top end. I'm going to buy a new one soon but I'll put this one back together for the kid that helps me some to use.


 


 

[JohnG28]

   Is the cylinder shot or still good?  If it's not shot I wouldn't put it back together and run it!  Actually, I wouldn't put it back together and run it either way.  You have something that needs addressing before that saw goes back to work.

[Maine logger88]

The cylinder is fine no aluminum transfer no scuffs or scoring. So you think there is something wrong besides just being wore out?

[Reddog]

if you can find the specs, mic the piston dia and see if it is under sized. If in spec you could try a new ring.

or just change out both piston and ring.

Look all the rubber and fuel lines over good, and air leak is always a possibility.

Edit: from the repair manual for low power trouble shooting.

Tank venting clogged
Blocked fuel filter
Impulse channel leaking
Blocked impulse channel
The cover on the carburettor
pump side is loose
Faulty pump diaphragm
Blocked air filter
Control system sticking
Leaking control system (air or
fuel)
Control system incorrectly
assembled
Loose diaphragm
Hole in diaphragm
Leaking diaphragm/cover plate

[Jiles]

What looks puzzling to me, is the transfer port marking on the piston skirt. I have built many engines and never saw that.
From looking at that side of piston, it appears to be the intake side (by the looks of the transfer port marking).
In most cases, damage to piston on intake side, is caused by dirty air entering engine.
With that being said and assuming exhaust side of piston looks good, I would clean with scotchbrite ,along with cylinder, and re-ring.
Very minor damage IMO.

[old guy]

I don't see any damage to that piston or the ring although it does look like it is not running rite,  take the ring off the piston and put it in the cyl. and push it in with the piston to keep it square, then you can measure the ring gap and you should be able to tell if the ring has lost its tension, no way a 562 should be wore out yet under normal use.

  John

[Maine logger88]

Thanks for the input guys! The top pic is the exhaust side of the piston. I am not sure what would be considered normal use but this saw has been worked real hard over the last year. I know the 2171s I had I could get 2 years out of but they didn't have to be worked as hard to keep pace lol.

[sharkey]

First thing I would do would be the pressure/vac tests on the case for the integrity of the seals.  If the piston is worn and the hours are high, I would replace the carb diaphragms, fuel lines, gaskets, bearings and seals as part of the service.  This way when you are done you know the saw is good for another season.   

Piston diameter according to the manual is 46mm or 1.81inch. Measure the piston skirt at the bottom to see if it is worn.  High silicon alloy gets harder and harder as its heated.  If you dont find any issues, re-ring it and put it back into service.   

If you want a pdf copy of the service manual, send me a private message with an email address and I will forward a copy.

[Maine logger88]

Ok thanks all good things to check! I'll borrow dad's mic and check the piston this weekend. The saw does have high hours but I just wanna put it back together for the guys to use and I'll buy a new one for myself! Thanks for the offer on the PDF manual but reddog already sent it to me!

[ehp]

that mark is on the ext port side of the piston , if it was me I would sand the piston where it is marked just to smooth the rough spot , check the ring to see if its got any wear on it or just put a new ring in it , your motor is running pretty rich , what ratio and try of oil are you using as that can do those kind of things as to make it run richer . What has the saw been cutting also , smaller stuff or larger tree as I find my 562's will get lazy if I'm cutting smaller stuff for say a day and it takes a will to get the autotune to reset itself back to where it was before . Now this is up to you but if you open up the muffler abit to help get some of the heat out of the motor that helps make the autotune saws run alot better , I have 1 562 here that I ported and it has cut over 2 million feet of hardwood and it has never gave me a single problem and it cuts alot of bigger hardwood , My stock 562 I donot even run much and I got other 562s here that I have not but much time on them some ported and xpgs

[Maine logger88]

I run husqvarnna oil at 50:1 ratio. The trees I was cutting the last couple days I used it were decent sized hemlock 12" to 18" dbh. I haven't looked anymore in to it cause I have been working on skidders and don't feel like turning wrenches at night lately lol. One of these days I'll put it back together tho...

[ehp]

logging here I cut very few trees that small, everything pretty much is 22 inch and up with about 30 inches as a average so , check the ring and sand the rough spot and put her back together and run the crap out of it  8)

[ehp]

check your cylinder above your ext.port , right at about centre of your ext. port , you should have a little buildup as that has marked your piston and check the ext. port to make sure its not carbon up as that will change the porting numbers in the saw and change the power of it alot , The other mark you see in the piston is the out line of the ext port when piston is at tdc, not very common to see this . There is a chance your ring is screwed right where that mark hits the ring so check that out very close as well

[Maine logger88]

Ok thanks I will check all that out next time I get a chance hopefully this weekend!

[Andyshine77]

The piston really doesn't look all that bad. Remember we are still dealing with an air cooled two cycle engine, with metal to metal contact, there will always be some signs of wear. I've personally had better luck, and see less wear running more oil 40:1 or 32:1. 

[joe_indi]

The piston really doesn't look all that bad. Remember we are still dealing with an air cooled two cycle engine, with metal to metal contact, there will always be some signs of wear. I've personally had better luck, and see less wear running more oil 40:1 or 32:1. 

I second all the above.
The deposits on the piston is  typical of an engine with stratification coupled with ignition controlled speed limiter. Maybe more from engine running at peak rpm. This causes the ignition speed limiter to cut off current to the spark plug creating  misfires at every other revolution.