Break-in

[Farmer_Nate]

Working on an old saw. I put a new ring in. What about "break-in". I searched, didn't find a lot on the forum.

My current plan:

Warm the saw, then cut hard, then idle to cool, then shut off. Repeat.

 

[sean donato]

Assuming the tune is decent. Warm it up a bit then go cut wood. Dynamic load is what the ring (s) need to seat properly, only way to get that is under a load.

 

[ballisticdoughnut]

Sharp chain. Fresh 40:1 mix. Run it as you normally would. You could tune it a touch on the rich side.

 

[Farmer_Nate]

Yeah, listen for the "4 stroke" before hitting the wood, H screw little rich.

 

[Farmer_Nate]

Assuming the tune is decent. Warm it up a bit then go cut wood. Dynamic load is what the ring (s) need to seat properly, only way to get that is under a load.

What is seating rings, anyway. I put the rings on the piston...they looked seated.

 

[Chevboy0167]

The ring seating process is accomplished by actual metal-to-metal contact between the ring and the cylinder wall. The ring’s job is to seal all the gases it can on the top side of the piston from escaping to the bottom side of the piston and into the crankcase.

 

[Chevboy0167]

And down the rabbit hole...

https://en.wikipedia.org/wiki/Piston_ring

 

[huskihl]

The piston is round, the ring is round, the cylinder is round. But they’re not “perfect” because that’s technically impossible. Break-in is referred to as the time before the ring has worn to the shape of the cylinder. I’d let it idle for a few minutes, tune slightly rich and cut wood. After a couple tanks tune it normally.

If you baby it, the cylinder walls can glaze and the rings will never break in

 

[Farmer_Nate]

The piston is round, the ring is round, the cylinder is round. But they’re not “perfect” because that’s technically impossible. Break-in is referred to as the time before the ring has worn to the shape of the cylinder. I’d let it idle for a few minutes, tune slightly rich and cut wood. After a couple tanks tune it normally.

If you baby it, the cylinder walls can glaze and the rings will never break in

Thaaaaaats more like what I was looking for. Wondered about that.

I'll giver 'er throttle but make sure H is set rich enough. Thank you.

Nate

 

[Chevboy0167]

if ya get bored, some light reading...

https://www.2strokeengine.net/gordonjennings/twostroketunershandbook.php
https://www.highpowermedia.com/Archive/the-two-stroke-ring

 

[2StrokeFondler]

if ya get bored, some light reading...

https://www.2strokeengine.net/gordonjennings/twostroketunershandbook.php
https://www.highpowermedia.com/Archive/the-two-stroke-ring

Skimmed over it, and the part about piston acceleration ist super interesting.

 

[Farmer_Nate]

I have been reading his book online lately. Interesting for sure.

 

[Pepster]

I always thermal cycled new saws (or new rings in your case).
Start it & let it idle for 5 or 10 minutes.
Repeat a couple of 3 times then put it to work.
Prolly unnecessary but it's worked well for me everytime.

 

[trains]

no need to let it idle for 5 or 10 min, just warm it up, and then cut at wot, let it work at its work rpm ie 9500, avoid wot with no load.
Then let it cool down before turning off.

Idling for prolonged periods do nothing but glaze up the bore in a new install.

 

[Pepster]

no need to let it idle for 5 or 10 min, just warm it up, and then cut at wot, let it work at its work rpm ie 9500, avoid wot with no load.
Then let it cool down before turning off.

Idling for prolonged periods do nothing but glaze up the bore in a new install.

I'm sure your right, but when I bought a brand new saw I had other components in mind when thermal cycling.
Rod bearing, wrist pin bearing, crank bearings & seals ect...

It's been awhile since I bought a new saw, & like I said I never had any problems doing it (no glazed cylinders).

I prolly wont do it again, but it's a good way for problems to show themselves @ idle rpm's instead of WOT.

 

[thenne1713]

Working on an old saw. I put a new ring in. What about "break-in". I searched, didn't find a lot on the forum.

My current plan:

Warm the saw, then cut hard, then idle to cool, then shut off. Repeat.

I have read that (some/all MFR?) say NEVER use SYNTHETIC OIL during Breakin, or rings will NOT seat.... SYN are that much better than dino oil

 

[bwalker]

I always thermal cycled new saws (or new rings in your case).
Start it & let it idle for 5 or 10 minutes.
Repeat a couple of 3 times then put it to work.
Prolly unnecessary but it's worked well for me everytime.

Great way not to get a proper "break in". The whole heat cycle thing is one of the stupidest old wives tales that two stroke enthusiasts spin.

 

[bwalker]

I always thermal cycled new saws (or new rings in your case).
Start it & let it idle for 5 or 10 minutes.
Repeat a couple of 3 times then put it to work.
Prolly unnecessary but it's worked well for me everytime.

Great way not to get a proper "break in". The whole heat cycle thing is one of the stupidest old wives tales that two stroke enthusiasts spin

I have read that (some/all MFR?) say NEVER use SYNTHETIC OIL during Breakin, or rings will NOT seat.... SYN are that much better than dino oil

That's a load of BS. In the first place most two cycle oils sold today are at least partially synthetic. In the second, as it pertains to chainsaws synthetics began to be used because they smoke.less and are cleaner. The "film strength" is not drastically different in the conditions a chainsaw is subjected to.

 

[bwalker]

I believed in break in for years. That was until I watched a really good engine builder break in a motor I had him build for my mod hill climb sled. He did it on a dyno at full load once the coolant was up to operating temp. It gained power with each pull until it hit a plateau. At that point it was broken in. By that point the pipes were so hot the paint had burnt off the header sections! That particular motor was monster and it lasted a very long time under heavy abuse.

 

[bwalker]

I'm sure your right, but when I bought a brand new saw I had other components in mind when thermal cycling.
Rod bearing, wrist pin bearing, crank bearings & seals ect...

It's been awhile since I bought a new saw, & like I said I never had any problems doing it (no glazed cylinders).

I prolly wont do it again, but it's a good way for problems to show themselves @ idle rpm's instead of WOT.

Glazing actually is a term used to describe the rings folding over the cross hatch on cylinder with out "seating" the ring. It can't really be observed visually. Instead it manifests itself as the engine making less power over its lifetime because the rings never seal as intended.