Stihl HT 131 New Generation Pole Saw

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Tree Reaper

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Picked up a Stihl HT131 yesterday and put it through its paces. Oh man I waited too long to get one of these! I’ve got an MS261 and 661, but being lifted into the canopy with an end loader tractor was just getting to damned hairy! Lol.

I originally called up for a HT133 but the sales rep said they pulled all the 133s due to problems. This new HT131 has a blend of features between the two of them. Basically best of both worlds. Running the carb at stock setting at the moment, but will tune soon. Will need to figure out the shoulder strap length and balance so I don’t roast my arms, but that’s easy enough.
 
Are they still 4 mix engines? I bought one 4 years ago spur of the moment without doing any research. I had no idea it was a 4 mix until later. Dealer did not tell me and their was nothing on the unit to indicate it. It runs and cuts good but the telescopic shaft keeps creeping out while it running. It doesn't matter how tight you tighten the clamp, it creeps out.

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Are they still 4 mix engines? I bought one 4 years ago spur of the moment without doing any research. I had no idea it was a 4 mix until later. Dealer did not tell me and their was nothing on the unit to indicate it. It runs and cuts good but the telescopic shaft keeps creeping out while it running. It doesn't matter how tight you tighten the clamp, it creeps out.

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Yes, 4 mix.
 
A google showed that 4-mix means 4 stroke. Hmmm. Does it use the same 50:1 premix that we use in 2-stroke saws? Why did Stihl go with this do you think... due to EPA stuff of because it has more torque or some other mechanical advantage? In other words, why this instead of staying with 2-stroke engine? Is this polesaw only available in 4-mix? Thanks.
 
Yes it's a 4 stroke with no oil resivoir so it uses 50:1 2 stroke oil. It has valves and a plastic camshaft. I don't know why they did it, their backpack blowers are 4 mix as well.

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A google showed that 4-mix means 4 stroke. Hmmm. Does it use the same 50:1 premix that we use in 2-stroke saws? Why did Stihl go with this do you think... due to EPA stuff of because it has more torque or some other mechanical advantage? In other words, why this instead of staying with 2-stroke engine? Is this polesaw only available in 4-mix? Thanks.
The EPA is likely the reason for the 4-mix. The torque is the advantage I enjoy. To be able To just place the bar on a limb and pull the trigger is much better than to have to hold it up, gain rpm, them make the cut.
 
What problems???? The new drive tubes are close to indestructible. They use the same engine.
The cutter heads have been under the scope due to it using 1/4 chain, when the engine could probably push .325.
Picco would be best.
 
Have so many questions!
1. 4 stroke with no sump to lube reciprocating assembly?
2. Pretty sure that subject of q 1 needs to happen, and they wouldnt use premix for any other reason, so how does that occur?
3. Standard aspiration for a 4 stroke would be through an intake passage directly to the intake valve port on the head(assuming this is OHV style engine.) How do they get the premix to the reciprocating assembly, and what do they do with it afterward?
4. I can understand the low end torque advantage on a pole saw, but what about backpack blowers? I know fans need torque, but they also need speed(horsepower) to move the volume of air required. What kind of rpm range do these things have?
 
Have so many questions!
1. 4 stroke with no sump to lube reciprocating assembly?
2. Pretty sure that subject of q 1 needs to happen, and they wouldnt use premix for any other reason, so how does that occur?
3. Standard aspiration for a 4 stroke would be through an intake passage directly to the intake valve port on the head(assuming this is OHV style engine.) How do they get the premix to the reciprocating assembly, and what do they do with it afterward?
4. I can understand the low end torque advantage on a pole saw, but what about backpack blowers? I know fans need torque, but they also need speed(horsepower) to move the volume of air required. What kind of rpm range do these things have?
There are some YouTube videos of these things that show you how they work and how to adjust the valves and such.

Sent from my Moto G (4) using Tapatalk
 
A google showed that 4-mix means 4 stroke. Hmmm. Does it use the same 50:1 premix that we use in 2-stroke saws? Why did Stihl go with this do you think... due to EPA stuff of because it has more torque or some other mechanical advantage? In other words, why this instead of staying with 2-stroke engine? Is this polesaw only available in 4-mix? Thanks.
To meet EPA restrictions on emissions is what I think. It still works good.
 
Have so many questions!
1. 4 stroke with no sump to lube reciprocating assembly?
2. Pretty sure that subject of q 1 needs to happen, and they wouldnt use premix for any other reason, so how does that occur?
3. Standard aspiration for a 4 stroke would be through an intake passage directly to the intake valve port on the head(assuming this is OHV style engine.) How do they get the premix to the reciprocating assembly, and what do they do with it afterward?
4. I can understand the low end torque advantage on a pole saw, but what about backpack blowers? I know fans need torque, but they also need speed(horsepower) to move the volume of air required. What kind of rpm range do these things have?
It runs around 8000 RPMs. The 4 mix blowers are great.
 
I also like the low noise of idle on a 4-mix. They sound like they are idling at 500 rpm, even though they are not with the put, put, put.

At idle, they always sound like they are on the verge of stalling, but don’t. Guess that’s what happens when you have a cam shaped like a pyramid.
 
At idle, they always sound like they are on the verge of stalling, but don’t. Guess that’s what happens when you have a cam shaped like a pyramid.
Flat rapper cams always sounded more radical than the equivalent roller cam. The ramps sure make a huge difference that don't always reflect their specs.
 
Ok, so I googles it.
Looks like it has a bypass port that keeps a certain amount of the mix swirling in the crankcase. I'm sure theres a return to keep it from building up. Seems like a decent system.
Ive been in the dark on this I guess. I knew about small 4 strokes somewhat, but older ones were heavy and not too reliable.
They do sound nice idling.
Kinda like when Yamaha introduced a 4 stroke to motor cross. Definitely a different sound.
 

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