Not the piston, the cylinder.
066.....What happened?
- Thread starter Adirondackstihl
- Start date
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Not the piston, the cylinder.
old-cat
Fir Man
Oooops!
Adirondackstihl
Flyz, Fuel & Fotos
The saw never seized up.
And I let it warm up before any WOT cuts were made
HuskStihl
Chairin'em for the sound
"I have a potty mouth" received! Just so ya know, my post wasn't for you
HuskStihl
Chairin'em for the sound
"I have a potty mouth" received! Just so ya know, my post wasn't for you
Deets066
Firewood hack
I just muffed a piston and stuck a ring, actually while I was checking tune let the saw warm up, made two cuts, was goin to check with tach. held it wot, rpm was good then jumped 3,500 rpm and died.
Come to find out the vent hose was split and leaking badly, and saw ran out of fuel just as I held it wot.
Come to find out the vent hose was split and leaking badly, and saw ran out of fuel just as I held it wot.
Adirondackstihl
Flyz, Fuel & Fotos
53.99mm across the transfers
53.99mm across the intake/exhaust
53.99mm across the intake/exhaust
cuttinties
ArboristSite Guru
Revving a cold saw would cause this
Good,..then the piston expanded just as it it is intended to do, but it swelled too quickly, the cylinder did not expand as quickly as the piston did. The skirts are always larger in dia than the crown but the whole piston expands so the skirt would actually be tighter in the cylinder for just a couple of seconds but enough for it to scuff itself badly. IMO.
But the saw was warm.... Think shrinkage.
Not necessarily, Explane that in an aircraft.
I wonder if the cold ambient air -6 f caused the cylinder not to get warm enough to have enough piston to cylinder clearance while it was running and working hard....the ex side might not be as tight as the heat from the muffler and always hotter on ex-side of piston. Does look like the most scoring on the intake is in the lower half of the piston where it is widest and where the lower portion of the cylinder is which tends to be smaller than the top dia.....sounds like the tune was sufficient for the weather conditions.....
Most of your pics aren't showing. Is it just me?
This sort of piston damage happens just as the engine starts up from a cold condition, the saw will still run for quite soime time afterwards but the damage has been done. I live in a cold climate, cold for 4-5 months of the year. I have seen many cold scored pistons come my way over the years. The cylinder is cold, it has cooling fins and more mass than the piston. The piston expands more rapidly than the cylinder.
Must be on your end Brad, they show fine for me.
J,
Have you had a look at the bottom end yet?
Maybe your answer is there. This is interesting.
Last one I had close to looking like this was FOD. (ate a bunch o crappage)
Have you had a look at the bottom end yet?
Maybe your answer is there. This is interesting.
Last one I had close to looking like this was FOD. (ate a bunch o crappage)
