Echo CS-8000 Mod

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FreakinCoolUsername said:
I do agree these are already very powerful saws and i like that they don't rev like a stihl, its why over the past couple years i have moved more tawords echo products. But the 80 cc saw line from echo is behind when you compare what length bar it can run. Mine has a brand new cylinder and a new piston, but struggles stay consistent in a cut with a 28" bar and skiptooth chain. Of course the only saws i can compare it to are a pro mac 805 and homelite 550.
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Well, you have got some impressive replies here now, wow that tunedpipe saw was impressive.
Anyway, I was about to suggest that if your 80cc is not what you expected it to be and you are slightly disappointed - it will ofcourse improve when properly run in, and you could do a muffler mod and such to further improve it. But if you are disappointed with it now I dont think that will make you entirely happy.
I wouldn't bother to mess up the saw trying to make it in to something else than what it really is, you might get a better sale on a original unmodified saw.
I think if you sold it and bought a 90cc+ saw like a MS 661 or a Husky 390/592, you would get more what you probably expect from cutting 28 inches of wood.
 
link said:
Well, you have got some impressive replies here now, wow that tunedpipe saw was impressive.
Anyway, I was about to suggest that if your 80cc is not what you expected it to be and you are slightly disappointed - it will ofcourse improve when properly run in, and you could do a muffler mod and such to further improve it. But if you are disappointed with it now I dont think that will make you entirely happy.
I wouldn't bother to mess up the saw trying to make it in to something else than what it really is, you might get a better sale on a original unmodified saw.
I think if you sold it and bought a 90cc+ saw like a MS 661 or a Husky 390/592, you would get more what you probably expect from cutting 28 inches of wood.
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I do agree a newer saw would probrobly be a much easier and reliable solution. I actually have larger saws already, though they are far from new and with the price of some of these newer saws t don't think im gonna be going shopping any time soon. I was interested in the echo replacement for th 80 cc series , the 7310. A dealer told me it has more power with a smaller displacement but its quite expensive as well. I kinda want to do this project just to mess around with modding saws, we'll see what happens currently i can't get a new muffler for the cs 8000 and i want to keep a stock one on hand. I cant get any spare cylinders ether and i don't want to chance ruining the one i have so for right now im gonna have to hold off until parts become available again.
 
Sierra_rider said:
Get some solder and measure the squish. On a saw, I'll go in through the spark plug hole until I hit the cylinder wall and then rock the piston over TDC a few times.

If the stock squish is around .030", you got a good candidate for a gasket delete. The gasket is probably around .020" thick, putting a layer of motoseal on will probably add back about .010", for a net loss of .010" squish clearance. Obviously, remeasure squish after you're done, just to make sure it isn't too tight. I shoot for about .020" squish when I'm milling cylinders.

Muffler mods are pretty easy. People argue about it, but I'm of the opinion that chainsaw mufflers are there purely for noise control, i.e. they don't provide tuning characteristics like the expansion chamber on a dirt bike. IMO, more open is better...at a certain point, you aren't gaining anything by going more open. As already said, gut the inside of the muffler(IDK if the Echo even has any baffling inside.)
The best bet is to weld on deflectors to whatever new openings you make in the exhaust. Some people cut slits in the exhaust and then pry them open to make louvers. On saws with one piece mufflers, I'll drill a hole and then weld a tube inside that hole. On my Stihls with 2 piece mufflers, I make a new muffler cover a la Bark Box style.

Porting is a little more complicated. As others have said, don't change port timing unless you understand how it's going to affect the power. On the face of it, I'd consider raising the exhaust port on a saw that didn't have much top end power, but that's an overly simplistic approach. Other factors like blowdown and intake duration. I kind of have a formula I stick to for timing numbers, but I'm not a pro tuner by any means.

I generally widen all the ports, just trying to get as much flow as possible. Like I said, I'm no pro, I just kinda imagine what shapes/sizes would give the most flow and velocity. I've built some bad-azz saws, I've also built some duds. Your Echo is probably a good saw to experiment on...Echo parts usually seem pretty affordable compared to the big 2, so if you do wreck a cylinder, it's not the end of the world.
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I wasn't planning on messing with the timing, if i ever need to replace the cylinder i want whatever mods i do to be easily repeatable. I would like to know more about how you calculate how large you can make the exhaust port?
 
FreakinCoolUsername said:
I wasn't planning on messing with the timing, if i ever need to replace the cylinder i want whatever mods i do to be easily repeatable. I would like to know more about how you calculate how large you can make the exhaust port?
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I've always heard that the exhaust port should be up to 70% of the cylinder diameter...and that's measured onto the circumference of the cylinder wall.

I don't really measure it, I keep it a little conservative and eyeball it. Keep a gentle arch on the top of the port and chamfer the edges.

On the intake, measure where the piston skirt lines up compared to the port opening, and make sure you keep the port inside the area of the skirt.
 
FreakinCoolUsername said:
okay thanks now how do you ensure you don't go to far? Do you just put the piston in the cylinder an see how it looks?
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I've always read that you want to shoot for a minimum of 2mm of distance between the edge of the port and the piston cut out, in order to make sure the piston can create a seal. That 70% rule can also apply here.

The actual desired width is also dependent on other factors, all the parts have to work together. You don't want a big wide intake, but then be stuck with a tiny carb, transfers and/or exhaust that can't flow it, etc.

If you really want to delve into porting, I'd recommend this book:

https://www.amazon.com/Two-Stroke-P...s&sprefix=two+stroke+pe,stripbooks,338&sr=1-1
It's gotten pretty pricey since when I bought mine, but lots of good info. Just bear in mind that dirtbike/kart engine tuning is a little different than saws, as saws typically have reed valves and tuned exhaust...but the fundamentals are still there. I'll also add that porting saws isn't an exact science. I'll often have a particular saw apart on a couple different occasions just to perfect what I've done.
 
FreakinCoolUsername said:
I do agree a newer saw would probrobly be a much easier and reliable solution. I actually have larger saws already, though they are far from new and with the price of some of these newer saws t don't think im gonna be going shopping any time soon. I was interested in the echo replacement for th 80 cc series , the 7310. A dealer told me it has more power with a smaller displacement but its quite expensive as well. I kinda want to do this project just to mess around with modding saws, we'll see what happens currently i can't get a new muffler for the cs 8000 and i want to keep a stock one on hand. I cant get any spare cylinders ether and i don't want to chance ruining the one i have so for right now im gonna have to hold off until parts become available again.
Click to expand...
A brand new MS661 powerhead only is about as affordable as you get. Thats a lot of quality and power for your money compared to anything else.
That will not disappoint at 28". I'm not saying "possible" to do a 28" - I'm saying that baby is made for it.
I had a Dolmar 7910, what a sweet saw with a 20" - I bet it could do a 24" nicely too.
 
you determine port width by measuring the piston skirt width vs the port width, you need enough skirt width outside of the port to support the piston safely. measure your squish and start there before attempting modifications on ports or timing.
 
cookies said:
you determine port width by measuring the piston skirt width vs the port width, you need enough skirt width outside of the port to support the piston safely. measure your squish and start there before attempting modifications on ports or timing.
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I'm not saying you are wrong, because I do not have the experience to do that.
But by mathematical preferences you should determine the port width by relating to the cylinder perimeter also. 20% is standard or "safe".
Especially if the piston rings pass that port, as for inntake my experience is that they are pretty wide and "big" to begin with.
More interesting perhaps is the width and shape of the exhaust port, that makes the engine fuel efficient at the cost of power.
So when the transfers opens to let the slight compression of gas in to the cylinder you better be sure the exhaust compression is already released, yes?
 
link said:
I'm not saying you are wrong, because I do not have the experience to do that.
But by mathematical preferences you should determine the port width by relating to the cylinder perimeter also. 20% standard.
Especially if the piston rings pass that port, as for inntake my experience is that they are pretty wide and big to begin with.
More interesting perhaps is the width and shape of the exhaust port, that makes the engine fuel efficient at the cost of power.
Click to expand...
Well thats how you can determine what the maximum safe width is. Someone that has never ported before needs to start somewhere and a base gasket thickness adjustment and raising the exhaust roof to match the thickness removed is where I would suggest starting but the fact I have never ported a echo I suggest starting with the squish alone to get compression up and look around for information about carb swaps and modifications to un choke it. When doing this work use a degree wheel to map out the port timing/blowdown multiple times over a period of a couple days to get used to it and comfortable writing it down then start studying port timing mechanics and realize it all shifts as you deck the cylinder.
 
FreakinCoolUsername said:
I do agree these are already very powerful saws and i like that they don't rev like a stihl, its why over the past couple years i have moved more tawords echo products. But the 80 cc saw line from echo is behind when you compare what length bar it can run. Mine has a brand new cylinder and a new piston, but struggles stay consistent in a cut with a 28" bar and skiptooth chain. Of course the only saws i can compare it to are a pro mac 805 and homelite 550.
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My stock cs590 with 24" bar full comp chain will chew thru red oak 20-24" diameter pretty fast, j would think that 8000 would have no issues pulling 28" in wood. Maybe it needs more tanks ran thru it
 
Brufab said:
My stock cs590 with 24" bar full comp chain will chew thru red oak 20-24" diameter pretty fast, j would think that 8000 would have no issues pulling 28" in wood. Maybe it needs more tanks ran thru it
Click to expand...
I picked up a free 8000 recently, they're dogs in stock form. A positive way to spin it is that they have "old school torque," meaning that the chain won't stall out, but it never spins very fast either lol.

I'm giving mine to my old man. I did some port and machine work to it and I'm betting on it the power to spin a 32" w/404 chain. I wouldn't normally run .404 on this size saw, but it's a spare Stihl bar that I'm not ever going to use...if he wants to run 3/8 on it, he can change the sprocket nose himself. I'm just waiting on some new rubber pieces for it and it should be good to go. The 35+ year old rubber didn't like being taken apart.
 
link said:
Perhaps you just expect too much from it, 28in buried in wood is gonna be tough for any saw less than 90cc.
I consider a 20 to 24in bar on a 70 to 80cc, it won't make you disappointed a lot at least. It should be able to pull 28 buried, with some patience and a sharp chain.
But when people brag about having a 28 or a 32in on their Husky 372, Dolmar 7910 or ms460, they likely do not usually use the full lenght of it.
If they did, they would probably not brag about it... no problem to stall a 70cc in 20 inches of wood if you are just a little impatient.
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I have a 7900 I run a 28” bar on with Stihl RS chain. I’ve had it buried in pretty dry oak, pulled just fine. And surprisingly quickly I mite add. Not bragging, just saying I was surprised how well it did. I’d much prefer a 90cc saw for that kind of cutting.
 

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