576 failure

[Marshy]

View attachment 67326

Works for me! Everything I read was word of mouth and I was always skeptical. Thanks.

 

[RIDE-RED 350r]

Only one question remains.... How can a 576 POSSIBLY over-rev??!!

 

[Nitehawk55]

Be a good thing if Husky stood behind failures like this and worked even harder at preventing them

 

[tickbitintn]

Well this one is a 2010 model and appears to be well used....

Sent from my XT1254 using Tapatalk

 

[species8472]

 

[Marshy]

Having the ring end gap over the center of a port is a piss poor design IMO.

 

[MERR6267]

I fixed a 576xp (non-auto tune) for a friend that failed the same way. The pin did not dislodge fully, but rather just backed out enough to score the hell out of the cylinder. I had to pry and hammer the cylinder off as the pin was stuck in the cylinder wall until the piston was out of the cylinder.

I still worry if he's going to bring it back to me after another failure some day. (he's just a firewood hack like me)

PM

 

[RIDE-RED 350r]

Having the ring end gap over the center of a port is a piss poor design IMO.

I don't think the locating pin and ring gap were located adjacent to the exhaust port.. I've never seen that on any 2-stroke engine I've ever had apart. Adjacent to the intake, yes. But the rings should never seen the intake opening.

What happened was the locating pin came out, and once that happened the ring rotated around until the gap ended up in the exhaust port, at which time the ring snagged the exhaust port.

 

[bwalker]

Pre ignition and detonation can both cause the locating pin to back out

 

[RIDE-RED 350r]

What would cause those on a stock saw though... This saw is stock right???

Seems like someone would have to advance the ignition timing a mile, like there would be almost no flywheel key left, some seriously bad fuel, or an extreme increase in compression due to mods for any pre-ignition or detonation issues to occur. These saws seem pretty forgiving as far as pre-ignition and detonation in my experience, even when modded fairly hefty. My 394 is happy as a clam on 91 oct Ethanol-free with 210lbs compression.

 

[bwalker]

Pre ignition can happen pretty easily with enough ash deposits on the spark plug. Add a lean condition and bingo.
Although by the sounds of things this is a common problem to this model

 

[RIDE-RED 350r]

Yeah, I was thinking a lean condition might be about the only way. But seems like it would have to be pretty lean, like piston damage lean to get to that point anyway. Interesting conversation though