461

If it takes air in from muffler it is not fresh, it is hot and burned.... That will not work as desired... Very counter productive.
If it does it will still just neutral the pressure as piston open port, not something you wish to happen when the pressure is negative and fuel air is sucked in at the intake, witch is open when exoust is closed.
 
Magnus said:
If it takes air in from muffler it is not fresh, it is hot and burned.... That will not work as desired... Very counter productive.
Click to expand...

Well then what do you want?.......... an air freshener with that?:lol:
By the time the piston is TDC the exhaust charge is already out the muffler's exhaust outlet, any remaining unburned fuel left in the muffler can be recycled back into the cylinder at that point of TDC .
Yes not "fresh air" but a much cleaner running engine with the recyling which keeps EPA happy.
 
No, if exoust is open when intake port is open the fumes go straight thru.
It can't work that way. Pressures take out eachother and it will not run. I did this a couple of times porting... Just to throw thr top end away and start over.

Stratifyed and X-torq all mean that it should not be unburnt fuel in muffler, the fumes sucked in are meant to be pure air, that is why there is so much problems as it lack the property's there is in fuel.
 
HolmenTree said:
By the time the piston is TDC the exhaust charge is already out the muffler's exhaust outlet, any remaining unburned fuel left in the muffler can be recycled back into the cylinder at that point of TDC .
Click to expand...
This is how the conventional engines work and have been for decades....
Like 357, 272, 372....
NOT like the X-Torq, strato engines they spent millions on and arguing environmental reasons.... Mental, yes, but has nothing to do with environment.
Marketing and emission race that we get to pay.......
 
Magnus said:
No, if exoust is open when intake port is open the fumes go straight thru.
It can't work that way. Pressures take out eachother and it will not run. I did this a couple of times porting... Just to throw thr top end away and start over.
Click to expand...
Yes but this 461 porting is different then the conventional design. Like I said the cutout on the bottom of the exhaust side of the piston at TDC is the only place to get air into the crankcase other then the intake port.
 
It could be an other way: If you shut down the gas supply a little before the TDC, only fresh air is sucked up throw the carb. Possible maybe, with the Mtronic carb.
Then comes into play the internal deflector (send the air up when the piston is high) and the piston ports (air goes throw them in the upper part of the transfer channels, ready to be pushed first in the combustion chamber when the piston goes down).

Just a thought, I don't know if it could actually work, we need some measurements on the parts to say what, like for the exhaust diversion. Impossible with only the pics.
 
HolmenTree said:
Yes but this 461 porting is different then the conventional design.
Click to expand...
Not in any way different than what has been used in conventional engines.

HolmenTree said:
Like I said the cutout on the bottom of the exhaust side of the piston at TDC is the only place to get air into the crankcase other then the intake port.
Click to expand...
It can not have both ports open at same time any more than it can brew coffey.

Marc-Antoine said:
It could be an other way: If you shut down the gas supply a little before the TDC, only fresh air is sucked up throw the carb. Possible maybe, with the Mtronic carb.
Click to expand...
This is possible, although it doesn't say it is very likely or functional...
Marc-Antoine said:
Then comes into play the internal deflector (send the air up when the piston is high) and the piston ports (air goes throw them in the upper part of the transfer channels, ready to be pushed first in the combustion chamber when the piston goes down).
Just a thought, I don't know if it could actually work, we need some measurements on the parts to say what, like for the exhaust diversion. Impossible with only the pics.
Click to expand...
The flow scheme is about the timing and pressures. Not so easy to speculate without more facts and measurements.
I guess the deflector is the bracket in center you refer to. I would think it leads down rather than up as there is no ports up like conventional cylinders.
But it seems kind of low to me to be able to direct flow thru intake port.

This is fun!
 
Be even more fun if they would market the saw here!

Now that I know they do in France, I think I'll go yell at them.:X
 
Maybe it's only a matter of time before she reaches the Danish market.

And what about import by the net like you do for the American gear?
 
I was told by Stihl in Denmark that it wouldn't be marketed here.
And as for importing it, I'd be screwed first time it needed a spare part.
 
I saw the error in my way of thinking after looking at the picture of this thing on another web forum .

The pictures showed things in a different perspective and I see now it's not freash air as Magnus had pointed out .What confused me was evidently in the pictures I first saw on this forum it appeared to have a set of lower transfers on the sides which in reality was a refection in the photo.

What also was pointed out by Joe in India was the fact the engine has a scoop like thing which evidently channels the air created by the fan action of the crankshaft .

It makes more sense now and really other than the placement of the lower transfers acts much like a 372 which has double channel upper transfers .Unlike the common Stihl design of one large port .So in essence rather than fresh air it appears just a better transfer design .

That transfer design would explain the odd cylinder design .


You know though in simple terms a better transfer of fuel is essentually what you are doing if you mod the thing and alter the upper transfers or cut in finger ports on a normal design .
 
I don't understand the fan thing...

It is pressures (+-)that make the gases flow, crank is of no use in this, quite the opposite really as it can restrict flow.
Solution to this was the "full circle cranks" but they reduce volume in case witch is needed to get a larger amount of fumes in until pressures are max.

I hope they finally give up on these fresh air saws again, as the chainsaw industry did once before in 30's...
 
I looked up these animations, thought it could be fun for some to see..

Stratro: http://www.youtube.com/watch?v=3LDN0c2lAsQ&feature=relmfu
X-torq: http://www.youtube.com/watch?v=IY7zQKw4qsQ&feature=related
Conventional: http://www.youtube.com/watch?v=LuCUmQ9FxMU
Conventional: http://www.youtube.com/watch?v=xV9jnWVeSB4&feature=related

Intake port on a two stroke can be regulated by a valve and be located pretty much any were bellow exhaust port.
On most saws the valve is the piston and its skirt that determine when it is open or not.
Same with the exhaust port.

Fuel air mix is let in crank case under piston, flushed up thru trancefers above piston and ignited. As they epand piston go down creating the power.
If both ports are open at the same time these pressures that drive the engine will take out each other and engine stop.
Example.
If intake is too high and open at BDC whn exhaust is too burnt fumes go out the intake as the valve is open. fumes don't know left or right or handle directions very well, they can't be told do this or that, they follow the easiest way. This is why it is so hard to change two strokes. They look pretty much the same today as ever if they work as they should.
 
Thought I would bump this thread since I am in need of a bigger saw for this 48" diameter Water Oak I am taking down next week. I really like power to weight ratio on this saw and the air filtration system looks nice. I would like to stick with Stihl since all my saws are Stihl and have good dealers near by. I have a small business and wish I didn't haven't this expense so late in the year but my 361 is not going to cut it. I figure the 461 would be the next step for now. So what do you guys think? Is the 461 a good saw for an Arborist who is occasionally using a 32" bar and chain for stump cuts and some big wood as mentioned above. Maybe 3 times a year for the 32" bar and chain on Oak?

Thanks! Mark
 
I wouldn't try to run 32" on a 70cc saw, if you already have a 361 I would go up to 90cc, you can always run a shorter bar on a bigger saw.
 
Run it. Its no big deal. If you used a big saw in big wood more often then I would say get a bigger saw. Get what you can afford and make due with it. We all do that to varying extents in life. Ive seen 044's with a 32" bar in hard wood. It was tough to watch, but the guy that owned the saw had to make due with what he had and at the days end, he made good money.
 
On second thought, I know someone that uses a 460 with a 32" in hard wood all the time. Its not a rocket, but Ive used his weapon a time or two and it gets by. Its not horrible. Not ideal, but not the worst thing in the world. Use a skip chain.
 
I'm with Chris...as little as you report the need for a 32" bar. Full skip chain, have it razor sharp and never get slack on keeping it that way...it'll do what you need if you are willing to be just a bit patient.
 
Well sounds like this saw could be the right choice. Years ago I had an 066 which served me well on several jobs that I recall. Last time I used 90cc was in 1999! My other highest powered saw was a 036 Pro which was a fantastic saw! I want to go back in time and slap myself for selling those saws then :( The 066 did seem like overkill at times that is why I think the 461 may be a nice medium. I can use this saw for now and it will soon likely pay for the next one. Now I just need to get better at bidding jobs :) Actually get better at a lot of things! that is for another thread though. Thanks guys for your input!

Mark
 
This is where I just have to pipe up and say that a 32" bar is overkill for that tree.
Sure, if you have one, go ahead and use it, but if you don't, no need to invest in one just to save a few minutes on one tree.
24" will do it nicely and matches the 461 better.
 
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