Chainsaw Engines - one ring vs. two rings

[kgb007stb]

I have noticed that Husqvarna utilizes one ring on all their 2 cycle engines while Stihl makes engines with two rings on the piston. I don’t want to turn this thread into a battle of one brand against another but do any of you who do professions where you use chain saws on day to day basis see any performance/lifespan differences between the two designs?

Both seem to be rock solid designs as these engines seem to last quite a bit under harsh conditions. I do know several people that use both models respectively for professional use and they seem to be quite happy with either model.

I’ve only had experience with Husqvarna, which was a huge improvement over an old McCulloch from the 1990s.

 

[MolaKule]

All of my Poulans had one ring. I always broke down the engines
after they died, usually after 10 years of wood cutting.

 

[steve20]

the Husky 455 Rancher runs sweet even after a few years

 

[Tom_T]

I've never noticed a difference in performance or durability. To counter the "more is better" argument I figure if the first ring seals say 95%, then the second ring is going to seal 95% of 5% or about 0.5%. Then again if worn rings seal 75%, the second ring makes a bigger difference. One ring gives you that much less weight that has to be slung back and forth about 150 times a second.

 

[bob_ninja]

I thought my older Stihl had a single ring when I rebuilt it couple of years ago. Not sure.
It doesn't really matter as they are easy to rebuild. You can easily replace a worn ring, so I would imagine that a single ring would be sufficient.

 

[Kestas]

As with anything that is engineered there are trade-offs. Though two rings may seal better, they also increase friction losses and cost.

 

[kgb007stb]

I always thought that on small engines that had one ring were much tighter in piston to cylinder clearance, thus no need for a second ring which helps stability to prevent piston slap. I’ve also heard that the second ring also help the piston in heat transfer thus cooling.

My husky 55 is still running strong.

 

[wileyE]

2 rings will transfer heat better, but some that use a single have a fat dykes ring with as much surface area as 2 thin rings.