Why would you want to do that ?

3/8" chain will be a bit much for your saw, you would need to keep it properly sharpened and take your time in the cut. Bar and sprocket probably not available in that size for the small Echo.

When I bought the cs4500 I was under the impression that it had the same chain size as my old echo saw. It has plenty of power to handle the larger chain. The smaller chain wears out much faster and requires more sharpening. The smaller chain is not good for cutting a lot of wood. This saw was just a little lighter and easier on my back than the old echo. I learned about the smaller chains a long time ago. Higher rpm's will burn up a smaller chain way too fast. I usually saw about half throttle to save gas, wear and tear on motor. Need larger teeth to do the job...

Thanks for the reply

If your chain was burning up my guess is you needed to sharpen it or your saw wasn't oiling well or even some other things.

How long the chain will stay sharp depends on the quality of the chain and how you are cutting. The size won't matter as nearly as much as the other factors. Remember, that smaller chain isn't moving as much wood as the larger one. I assume you are talking about small/large in terms of pitch (the distance between the cutters) and not "normal" and narrow kerf chain.

I've gone back and forth on 3/8 and .325 pitch chain on my MS260. I've stuck with the .325 chain because it is a better fit for how the saw gets used. I could run 3/8 if I wanted, but I have found no reason to pay for new sprockets and bars that would justify the cost.

Narrow kerf chain is a different subject. It can work well on smaller saws but is generally avoided as saws get larger. I have one saw that it is all I would use on it because I need that saw to be as light as possible. I have other saws where they have more horsepower and I need the durability.

In the end it is more a question of application.

Keep the chain sharp, the bar straight, the rails adjusted, the oiler oiling and avoid debris, those are the most important things you can do.

You are using half throttle to save wear and tear on the saw? That is false economy and not safe the risk of kickback is increased. The saw is designed to run at full throttle for maximum power and cooling, lower rpm means the saw will lug and run hotter.If you are burning up a chain at full speed it is not properly sharpened. 3/8 chain will bog the saw down, likely stall it.