Husky 346xp piston cylinder issues

[Frazer Burley]

52 minutes ago, spudulike said:

Looks like the gudgeon pin has worn on one side....measure both ends and compare to the middle. One end will probably be smaller than the others.......strangely, the pin often wears and the piston doesn't.

 Seen this on old OEM pistons...one a 064 Stihl and also on  Nepias 262XP .

The actual piston doesn't look too bad.

The marking around the exhaust port looks pretty iffy and shows signs of seize.

If that ring location pin has fallen out, it won't be holding the ring in place - if the ring is pushed in to the grove, does the pin hold it? if not, it has gone.

You usually take out the piston in a big way when they fall out....or they end up embedded in the combustion chamber squish band!

Weirdly the gudgeon pin is worn with indentation of the needle bearing only on one side, the other is smooth. And I'm talking not laterally on the pin.

 

ring location pin was gone allowing piston ring to rotate around and fused onto piston.

[spudulike]

2 minutes ago, adw said:

Not that bloody crank seal again!

Look me old mucker...In time they leak, and if they leak, I change them. The manual says about pressure testing only but cock all about vacuum testing. This is tosh as I have had saws with idles that are unacceptable but by the word of Husqvarna are fine on the stated pressure only check. They FAILED on MY vacuum check and guess what fixed them....A NEW SEAL!!!!

You know how two strokes work, air should only enter through the carb and not leak pressure or vacuum from anywhere else on the engine. I have done enough 346s to know by now......and you know it

[Frazer Burley]

34 minutes ago, Stubby said:

Are you sure it was neat petrol and not an air leak . I ask coz putting on another pot and piston if it is an air leak will just let it nip up again .

Yep sure of the misfuel but totally agree on pressure testing before going ahead. Looking at kits now....

[spudulike]

Just now, Frazer Burley said:

Weirdly the gudgeon pin is worn with indentation of the needle bearing only on one side, the other is smooth. And I'm talking not laterally on the pin.

 

ring location pin was gone allowing piston ring to rotate around and fused onto piston.

Possibly a bent rod, had that on a 630 once - the only way I realised was the way the cylinder rocked when held down lightly and the engine was turned over slowly! You tend to get scuffs on the sides of the piston.

[Frazer Burley]

5 minutes ago, spudulike said:

Possibly a bent rod, had that on a 630 once - the only way I realised was the way the cylinder rocked when held down lightly and the engine was turned over slowly! You tend to get scuffs on the sides of the piston.

what about scuffs on the side of the rod?

[Khriss]

58 minutes ago, Frazer Burley said:

Yep sure of the misfuel but totally agree on pressure testing before going ahead. Looking at kits now....

Just buy a new 550.... I did 😇 K

[spudulike]

That's a bit strange, no reason the rod should be like that as there is nothing to contact it. Perhaps someone has done something with it they shouldn't have....weird!

[Frazer Burley]

15 minutes ago, Khriss said:

Just buy a new 550.... I did 😇 K

That’s the thinking but I also want to not just scrap old saws. 

[Frazer Burley]

14 minutes ago, spudulike said:

That's a bit strange, no reason the rod should be like that as there is nothing to contact it. Perhaps someone has done something with it they shouldn't have....weird!

Pretty weird. But no sign of something obvious?

[Ratman]

If you rotate the crank can you see any signs of wear on the insides of the crank webs/counter weights?