Wrist Pins.......

[Basher]

View attachment 90363 View attachment 90364

Just drill out the center of the AM pin.

 

[Deets066]

Just drill out the center of the AM pin.

You could, but the oem is tapered for a reason

 

[Adirondackstihl]

If the KS is a new piston then that would be my choice. Check crown height though, I bet it's lower.

I misspoke
It’s not a KS.
One is Mahle, the other is Stihl

 

[Deets066]

I misspoke
It’s not a KS.
One is Mahle, the other is Stihl

 

[Adirondackstihl]

You could, but the oem is tapered for a reason

I assume it’s more than for weight reduction.

If drilled or counterbored, that will create a failure point within the ID of the pin.
Not a good idear

 

[MustangMike]

I ordered a new piston for my 10 mm 044, figured while I was deleting the base gasket I would replace it.

The new piston was a Mahle, the orig a KS. The KS has wings and is taller. The skirts measured about the same diameter. I still have the Mahle piston in a box, the original piston and rings are still in the saw. Runs just great!

 

[Deets066]

I misspoke
It’s not a KS.
One is Mahle, the other is Stihl

There is. a significant difference

 

[Deets066]

I assume it’s more than for weight reduction.

If drilled or counterbored, that will create a failure point within the ID of the pin.
Not a good idear

The oem pin has some "meat" where needed, then tapers off to reduce weight.

Oem is the only choice for me... cept for dem titanium uns

 

[Deets066]

I ordered a new piston for my 10 mm 044, figured while I was deleting the base gasket I would replace it.

The new piston was a Mahle, the orig a KS. The KS has wings and is taller. The skirts measured about the same diameter. I still have the Mahle piston in a box, the original piston and rings are still in the saw. Runs just great!

Whole different deal here Mike, has nothing to do with wings or 44's. But crown height and skirt length

 

[Adirondackstihl]

 

[Deets066]

View attachment 90370

And..... measure dem fackers

 

[Termitebuffet]

I misspoke
It’s not a KS.
One is Mahle, the other is Stihl

2 demerits. ....turn in your gold star ...[emoji2]

 

[Adirondackstihl]

2 demerits. ....turn in your gold star ...[emoji2]

Only if you take engrish crasses

 

[Termitebuffet]

Only if you take engrish crasses

I tookka de' maf

 

[Adirondackstihl]

Mahle = 88g
Stihl = 91g
Meteor = 96g

 

[Al Smith]

I've always wondered about that Al. As you know, McCulloch offered up to .050" over pistons for certain engines and say, a .050" over piston for a 125 is a lot heavier than the standard sized slug. Even a .030" over piston is quite a bit heavier. My dad had several 125 and 101 over-bore engines in his saws and he never really said anything about spool-up or more torque in the cut. But in his case bar length was probably a factor as he was running 42" and 60" bars.

I know making the reciprocating assembly lighter in some modern saws like the 066/660 can reduce vibration to a point or change the frequency of vibration so it's easier on your hands.

at one time I think Horstman had larger than 50 thou over .
10-12 years ago when I bored out the plated cylinder on a 125 it was 70 over but of course with the cast iron sleeve it was back to stock .I'm not sure how much more those big slugs in those 140 cc 3120's weigh over stock,strokers that Cliff H made or maybe still puts together .Never the less it's a good subject of debate if a few grams make that much difference .

 

[MustangMike]

Adding any weight to the reciprocating mass, or increasing RPMs, increases stress on the engine exponentially.

Luckily, chainsaw motors are generally over built, so we get away with ported saws and Hybrids!

It is also why I don't run 50:1.

 

[Adirondackstihl]

Think I can take 6g of mass off this meteor piston safely?

 

[Terry Syd]

increases stress on the engine exponentially.

A lot of people don't readily grasp this concept. If you have an engine running at 2,000 rpm and double the rpm to 4,000, the forces aren't twice as much, they are FOUR times as much. Double it again to 8,000 and the forces are 16 times as much. At 12,000 they are 36 times as much as an engine at 2,000.

The faster the engine turns, the more mechanical friction it produces and the more stress it puts on the components. A shorter stroke will reduce piston speed and acceleration, chainsaws are very 'over square' with short strokes so that they can run at high rpm. After working on bikes for years, the rpm that saws turn still intimidates me. - I admit to trimming every bit of extra weight off the piston and pin I can, LOL.

 

[Time's Standing Stihl]

Think I can take 6g of mass off this meteor piston safely?

Easily