which way does the arrow point new piston
- Thread starter somebum
- Start date
Help Support Arborist Forum:
manual
Addicted to ArboristSite
Exhaust side. ring gap towards intake side.
chainsawjunky
ArboristSite Guru
I just looked how to install for an 044 off of Baileys and they said towards exhaust. Evan
Tzed250
Addicted to ArboristSite
Arrow on piston should always point to the exhaust side.
Tree Sling'r
Addicted to ArboristSite
That may be why you needed a new one.
tek9tim
ArboristSite Guru
Yeah, forget arrows, this will always guide you home.
hornett22
Addicted to ArboristSite
the arrow............
always goes with the flow.
always goes with the flow.
West Texas
ArboristSite Guru
Old Saying: "He who asks question, looks stupid for few minutes. He who don't ask questions, stupid forever." You got the correct answer in three minutes; and, its neat to ask before installing the piston, instead of afterwards. Good luck on the rebuild.
GASoline71
Mr. Nice Guy
He would have had to reverse the chain since the saw would now be running backwards.(Just kidding.)
HAHAHAHAHAHA!
Gary
hey i didn't install the old piston that would be stihl themselves i had a snowmobile that would backfire on start up and run backwards it was always a joy to pin the throttle and hit the barn backwards instead of going away from it
sawinredneck
Addicted to ArboristSite
UP!!! Duh!!!!:hmm3grin2orange:
bushinspector
ArboristSite Operative
I have always said that their is ONLY ONE STUPID QUESTION ....
That is a question that you already have the answer to!!!!!!!
That is a question that you already have the answer to!!!!!!!
West Texas
ArboristSite Guru
The open end of the rings are to face towards the intake port, which is usually smaller, different shape, etc and the ring ends will not 'catch' on this port. The exhaust port is larger and wider, the ends of the rings will usually catch on the edges of this port. As a minimum it can damage the ring ends and affect compression. :censored: As a worst case the ring ends can catch in the exhaust port and destroy both the piston and the rings. This usually means a new cylinder as well. That's why the 'arrow' is on the side of the piston 'opposite' the open end of the rings. Put the arrow side on the exhaust side and live happily ever after. 
Last edited:
Tzed250
Addicted to ArboristSite
Sometimes...
some pistons have offset wristpin holes so that the combustion pressure has a straighter shot at the crankpin and the load on the intake side skirt is reduced. A flip of the piston would send that all out of whack.
some pistons have offset wristpin holes so that the combustion pressure has a straighter shot at the crankpin and the load on the intake side skirt is reduced. A flip of the piston would send that all out of whack.
logger_ head
New Member
I was about to install a new AM piston&cyl. on my 024av super and see that the arrow actually points to the ring gap pins which I believe is not right. I bought this saw from Ebay ad. stated it had low compression. I thought probably a scored piston, no big deal but in disassembling it I see it has a 42mm piston in a 44mm cylinder I guess from an 026. That piston is like new since the saw never ran and the rings didn't seat. I plan on using that piston in the new 42mm cyl. with Caber rings. I purchased the piston kit from Hutzl in China and I assume the arrow was mismarked on the piston.
None of these rules works every time. (Ain't that just the way?) For example, I have in my hot little hands a new piston for a TS760, and it is marked with an arrow that points toward the ring gaps. The old piston I took out of the same saw was marked the same way. BUT I also have here a used piston from an MS180. That one is marked with an arrow that points away from the ring gaps. Just to add a bit more confusion, the "ring gaps toward the intake" and "ring gaps away from the exhaust" rules don't always fly either. In my examples, the MS180, like the majority of saws, has its intake and exhaust ports on opposite sides of the cylinder, and the piston was installed with the gaps toward the intake. But the TS760 cylinder has "stacked" ports -- both on the same side of the cylinder, and the original piston was installed with the ring gaps toward both ports. The only "rule" I can see that applies in both these cases, assuming the old pistons were installed correctly, is that the arrow should point toward the exhaust port. With the MS180, that puts the gaps toward the intake and away from the exhaust. With the TS760, that puts the gaps toward both ports, BUT the ring gap pins are widely enough separated that they don't show through either port.
Clear as mud?
Clear as mud?
