TS 410 concrete saw carb and engine question

[Ax-man]

My main question here on this 410 concrete saw is this a strato carb for one of those stratified engines?? I am a little behind the times on some of this newer stuff because I have only done some reading and seen a few pictures on these engines and carbs . This is my first hands on experience with this type of carb that came in where I work part -time It started out with just a bad purge bulb that led to a total carb swap. My boss couldn't answer the question for me because he hadn't been to Stihl school for over 10 years . He also told me he isn't up on any of this M tronic stuff either even though they sell saws that are equip with it.

Bear with me here , if I have this wrong please let me know.

Pic 1 is a pic of the carb when viewed from the front or what I would call the airbox / air filter side . Bottom brass barbed fuel line goes to gas tank . The top two brass lines are for the purge /primer lines going to the remote plastic bulb . Choke plate at bottom with those three holes for the torx bolts to mate airbox to carb to intake manifold boot . I know a concrete saw is a different kind of animal than a chainsaw but would a chainsaw have a some what similar kind of mounting if it had this type of carb???

Pic 2 is just a view of the lever set up linking those two intake ports.

Pic 3 is a view of the intake manifold side or boot showing the pulse hole and how the carb would look at idle with both throttle plates in the closed position.

Pic 4 is a view of both ports in WOT with both throttle plates in the open position. The upper port is where that charge of raw air enters the cylinder in a strato engine during the compression part of the cycle . Do I have this part right or not ??? Like I said I am behind the times on this .

Pic 4 is a view we have all seen before with the carb adjustments for the carb.

This is a first for me which is why I am posting this just to satisfy my curiousity or is this just some kind of fancy carb only for a concrete saw.

Just a side note , I have worked on what I would call kind of complicated chainsaws but they seem simple compared to a concrete saw . They mean business almost to the point of being over engineered but considering the work environment a concrete saw has to survive in I can see why they are built the way they are .

 

[stihl86]

There are many chainsaws in the Stihl lineup that use that style engine. Check youtube. The workings of that design is covered. None of the saws use a primer. As for being over engineered, I couldn’t even begin to think about designing such a thing. But, I’m am an expert on criticism of any design (of anything)LOL

 

[Brent Nowell]

Yes that is a strato design. The upper portion is the port that regulates just air, and the bottom portion is what regulates an overly rich mixture of fuel in air.
The pump and metering section are always attached to the portion that regulates fuel and air.

Strato carbs usually have two sections like shown, and the fuel delivery port and butterfly is usually much smaller than the air delivery port. This is why it’s usually two full turns out on low and high for a strato engine and not the older one turn. It has to compensate for fuel for the added air port above.
There are other designs that incorporate the original single Venturi but with an added vane that separates fuel air charge from another air charge. The boot downstream of this point will have two channels as well

Is it the same type of carb as other stihls? I’m not sure but most likely
The carb will have identification on it that you can search on google or here and find out.

Basically a rebuild is the same as a non strato carb other than removing the upper port to get at the fuel pump portion of the carb

 

[Ax-man]

Thanks, good explanation. I did go over to You Tube , not much there for chainsaws but enough for the basics. Things are becoming clearer the more I read it just takes me time to digest all the info.

I think I have that charge of raw air a little backwards to when it gets introduced into the cylinder . It enters the cylinder during the scavenging part of the cycle for a cleaner burn of the air /fuel mix to be emission compliant. I need to get my hands on a strato engine to see how the piston and cylinder along with a carb actually work to see how it all falls into place . It will happen some day .

I do know more than I did before . Thanks again.

 

[Brent Nowell]

What I can tell you is that it is very fuel efficient and has similar power if not the same. It is in essence the perfect tech for a guy using a chainsaw 8-10 hours a day. Less filling up.
For the epa it touts better emissions, and they have the power to just shut you down so pleasing them is key.

There are some models that do not have stratification, somehow they are omitted it seems. They are almost always the higher end displacement models.
There are other models that are lower end but they use a Catalytic converter so they can get away without having it.

In the end it is more advanced and anything more advanced has more variables to work around. Not having it technically speaking is better in terms of reliability.
Lower end models that use it like the current poulans are much harder to tune due to the ****** carbs that come with them. Imo a good carb is key to getting stratos to run the same as their older counterpart

I want to tell you more, but I don’t want to give you the wrong info on how exactly it works. My understanding of it is still limited, there is so much engineering behind it it is hard for me to fully grasp
For me to grasp a two cycle engine and everything happening with the primary ports and strato ports at the same time is a tough cookie to swallow. But in time with enough tinkering and reading I will get it
There are good threads here in how stratification works. If you want to know more search within this forum

 

[alexcagle]

Mostly good info.
On your origional post:
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The top right barb in your pic goes to the port on the right rear of the clean side of the air box. It is the compensator line.

 

[Ax-man]

Thanks for letting me know , your the man when it comes to these concrete saws. I have only worked on a few of them so far and this was the first one I had to get the top cover off of to get at that purge bulb to get it fixed and then have to go back in second time to get the carb changed out so the darn saw would run right . It was challenging for me to say the least because there just isn't much wiggle room to change out parts let alone see where all the lines go. I'll remember this for sure and check it out if it comes up again and I am sure it will . I'm going to take that carb apart some day to see how much different it is from a regular carb.

Thanks again

 

[alexcagle]

It's not much different than a regular Zama C1U style carburetor. Once you remove the "air shutter", which is really all it is, you've got basically the same carb that goes on a conventional 2-stroke saw.
The air shutter for the stratified charge has a slide linkage so that it just starts to open up above half throttle.