my english might be bad, but i try my best...
*piston ring pin/stopper loose in piston after few (to 100) hours on it. result: wrecked Cylinder & Piston. *** not seen after 2015...
*crankcase gasket leakage. result: scored Piston & Cylinder ***fixed with new green gasket, and later with new crankcase (6bolt style, one half magnesium, other aluminium) ***still if the 5series saw comes to shop im able to tighten these screws
*cylinder gasket leakage(tightening bolts regurally is needed, by the client/owner also). result: scored Piston & Cylinder ***fixed with silicon-bond between cylinder and crankcase(but case halves are still warped, not on the same height...)
*cylinder transfer covers and seals leakage. result: scored Piston & Cylinder. ***still appears time on time
*crankshaft or bearing failure, crank spins in bearing(no matter what side). result: bad vacum/pressure in crankcase. result: saw wont start, work properly when engine cold or warm. some had scored cylinder piston aswell. ***not seen after 2015....something changed in manufacturing, tighter tolerances/bearing seats maybe, but the crankshaft is still hollow inside and it is in my perspective view a weakspot...
*crankshaft lower needle bearing breaking, big tolerances. result: basically worst what u can imagine, seen also splitted rods. everything is possible
***still seeing it to happen....
*crankshaft bearing breaking both sides. result: engine is permanently stopped. have seen also working ones, but these were only making some kind of dying noise. ***not seen so often anymore, new bearings with tougher races...
*carb failures(maybe due a bad patch of fuel, maybe bad part from the carburettor supplier...). result: saw wont idle, rev up, or even start. ***still happening
*heavy abuse of the saw, dull chain and large wood, very dirty chainsaw, low cooling effect, overheating - the engine/ECU do not now what to do. result: piston ring burns in piston groove due carbon ***still happening
*have seen also a non quality JASO FB fuel mixig oil fail, due the lubrication and overheating - the engine/ECU also wont know what to do. result: piston ring burns in piston groove due carbon.
*have also seen after 150 hours, the worn out oil seals on both side of the crankcase. Result: saw wont idle, rew up, and some times scored piston & cylinder.
and yes i still like Husqvarna saws. in winter the 550xpg is just awsome
