Chainsaw Piston Orientation - Design Question

[Farmer_Nate]

I am working on an old Echo saw, a CS-351 VL. The carb, spark plug, and exhaust are in the rear, closest to the user. The cylinder is basically horizontal. This puts oil and gas tank up front.

It seems most saws have the cylinder nearly vertical, with carb toward the user and exhaust forward toward the bar.

What are advantages and disadvantages?
I noted that the vertical piston saws tend to have fuel and oil fill ports on the left.

I noticed some top-handle saws have a horizontal cylinder.
Why? Cooling? Cost?

 

[NSEric]

It's all about ergos.
You can make the saw shorter front to rear if the cylinder is upright and this is better for normal handles as the rear handle is behind the motor.
Top handle saws have horizontal cylinders as it makes them shorter top to bottom which is better with a top handle as the handle is on top of the saw.

 

[Farmer_Nate]

Ah

Fit

 

[link]

cylinder is basically horizontal

A horizontal cylinder makes for a different torque feel (try to twist an angle grinder running at 10k you know).
I might be way out on this but I might be some right too...
I know tree-worker guys like horizontal aligned cylinders - WHY IS THAT?

 

[Old2stroke]

Vertical cylinders can all be piston port intake design whereas most (not all) horizontal ones have to use reed valves for induction. Main difference in using them, is more low end power with the reed valves but often a lower top rpm. Older saws with reed valves were known for their torque. Vertical cylinder has fewer parts to go bad.

 

[Farmer_Nate]

What does cylinder orientation have to do with intake style? Most saw engines would run upside down or in any orientation, wouldn't it? Why reeds for horizontal? Doesn't sound quite right, but...I am the one who asked.

 

[Old2stroke]

What does cylinder orientation have to do with intake style? Most saw engines would run upside down or in any orientation, wouldn't it? Why reeds for horizontal? Doesn't sound quite right, but...I am the one who asked.

It's all a matter of where on the saw is there enough space to place the carb. On large horizontal cyl engines, an intake port on the cyl would require the carb and intake filter to be concentrated to the rear of the engine, making an awkward shape and there could be an issue with the design of the transfers since the intake would be at 90deg to the exhaust port. Moving the carb closer to the base of the cyl and feeding it directly into the crankcase through a set of reed valves seems to be a better way to go.

 

[Farmer_Nate]

I think reed valves are mostly obsolete now on saws, but I understand. Intake lower on the crank is good to feed oil to bearings, then squishes up to the top for burning through transfers.

 

[Lightning Performance]

200T is limited by the carb size and air filter imho. Great tool though. It's a horizontal cylinder with the intake on the top and exhaust on the bottom. Cross flow motor with quad transfer ports. The carb is too small just like the 201T. I'm building a 200 rear handle to see if the little engine has more in it with a bigger carb and a few other changes. It should answer my questions. It has no reeds. The old reed saws were case feed these are piston ported like an upright model rear handle. They differ from many other designs with regards to a side exit exhaust port. Echo 2511 is cross flow inside but they used an angled port for side exhaust exit setup instead of out the bottom. Other non reed motors have a top intake with a side exhaust port. The cylinder exit is 90* to the intake. 200 and 200T models are 180*.
They both use the same base engine just like the 201-201T and different plastics to dress them top vs rear handle.

19X models are purpose built cylinders that do not interchange with other T models. Same with other manufacturers that I'm aware of. One is a clamshell type design in the 19xT models. The 200 and 200T models have split style pro case design and bolt on cylinders. These are the main differences in top handle designs.

 

[Farmer_Nate]

Nice

 

[Valpen]

200T is limited by the carb size and air filter imho. Great tool though. It's a horizontal cylinder with the intake on the top and exhaust on the bottom. Cross flow motor with quad transfer ports. The carb is too small just like the 201T. I'm building a 200 rear handle to see if the little engine has more in it with a bigger carb and a few other changes. It should answer my questions. It has no reeds. The old reed saws were case feed these are piston ported like an upright model rear handle. They differ from many other designs with regards to a side exit exhaust port. Echo 2511 is cross flow inside but they used an angled port for side exhaust exit setup instead of out the bottom. Other non reed motors have a top intake with a side exhaust port. The cylinder exit is 90* to the intake. 200 and 200T models are 180*.
They both use the same base engine just like the 201-201T and different plastics to dress them top vs rear handle.

19X models are purpose built cylinders that do not interchange with other T models. Same with other manufacturers that I'm aware of. One is a clamshell type design in the 19xT models. The 200 and 200T models have split style pro case design and bolt on cylinders. These are the main differences in top handle designs.

Getting even more out of a MS200 sounds like an interesting project. Pls keep us posted with your progress and findings!!

 

[Lightning Performance]

Getting even more out of a MS200 sounds like an interesting project. Pls keep us posted with your progress and findings!!

Getting more out of anything is fun to me. Purpose built is more interesting overall.
So a custom filter, not good for the woods or storm cleanup, bigger carb and the muffler is already done with a large rear edit now. Should work good considering the 200 or 200T isn't that hard to get more power out of. I do believe it is air limited because of the carb and filter. The T is the tight package and can be made to have more than enough if your smart about fuel management. Not something to be overlooked in any T model anything modified or otherwise going up the tree. Buckets, lifts and such are a different thing entirely. I work alone most times now on the ground or not. Being faster is just better when it's time to chop, drop and chop. My chipper stays home now. I may consider this tool for chunking down with an 18" bar. picking up a modified and ported 026/260 compared to the 034/034S/036/360 makes me grab the bigger saw every time. 50cc saws have no place here and I'm selling all of mine. They just don't get used much or never. Too many 362s also need to go away. I got two hands and forty saws give or take.

Just needed a fast dependable purpose built tool nothing more.
200Ts
200
034s
034S
360P
about covers the chunking operations nicely.
Other saws are heavier and feel like mush in my hand including
192T, 3, 4, 201T, 201, 261
241 isn't stiff enough for climbing to me. Good ground tool.
Huskys or Husky T models or under 90cc all sold, bye bye.
Still some 50-70cc Echos and Echo Ts here that also need to go along with all the other top handles in ever brand just sitting now days.
The rest is all big saws or 361s, 362s, 362C, bigger Dolkitas 64-84cc.
Don't really use the 044, 046/044, 460, ect, ect.
Do use the 92cc and up in many brands but not off the ground any more unless it's a fat tree for few cuts to get logs. Bucking, milling or stumps is their intended use here. The 200 is a unicorn that can't breath imho. Wish it had a heavier flywheel. The cylinder is finished for this 200, again, because it was on a 200T with all the stuffs. Need to fit a popup piston or not. Make the carb swap and bolt on a Vstack to test it. Still looking at carbs or modified carb options for a bigger intake boot, already installed, on the 200 model. It not far from finished. The next gen 034 is about done to test the pair together.