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New member here, need help and advice.

1. I have old STIHL FS80 trimmer that I want to bring back to life.
2. Don't ask WHY I want to repair it instead of buying new. Ok, I will tell. It's a challenge now to make it run! Plus, I like how sturdy it's built and feel bad about throwing it away.

Now details on what's going on.
1. It has older style TK carb with a slide (last picture)
2. I did try to replace gaskets, got fuel pump going, got it running but it was spitting out fuel out of overflow.
3. By doing some research I figured this carb has built-in valve that is non-repairable.
4. STIHL used to sell re-carb kit with adapter and new carb. Not anymore and was expensive.

I want to re-carb it myself now. Couple questions:

1. I guess engine is the same and I can use ZAMA carb from newer FS80 (new carb on picture)
2. What is the best place to get those kind of parts?
3. I will be machining adapter plate (carb to cylinder) out of aluminum. ZAMA carb has 2 holes in it. One for engine pulse for fuel pump, what is the other one? Also small hole(#3 and #4 on picture).
4. What is the proper orientation to install carb? Bulb on top/side/bottom?
5. What is the proper fuel hose arrangement? Old tank has only one hose coming out and it has pump bulb on it. I assume I will have to take it out (valve) and run hose directly to carb. What is hose #1 and #2? My newer trimmer has 3 hoses. One for fuel, one for return and one has small thingy on it. Breather? Do I have to do the same kind of arrangement with my re-carb?
6. I will have to get small filter box (with built-in choke). Are they pretty standard? What is the best place to get one?


Any other suggestions?

Totally different animals. Could be done, I guess, but you would need to replace almost everything. Tank, air filter assy., throttle trigger/lines/etc.
So any brand could work, but no one has tried it.

Please post all the engine numbers. My boss is an old Stihl guy and I would like to see if he has any of the parts you need. He has tons of old parts both new and used.

Fish said:

Totally different animals. Could be done, I guess, but you would need to replace almost everything. Tank, air filter assy., throttle trigger/lines/etc.
So any brand could work, but no one has tried it.

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Yep. This is what it is going to be. I will replace:
1. Adapter plate (DIY)
2. Tank stays, I will add another hose, this is not a problem
3. Throttle line - no big deal, just make a braket.
4. Air filter assy - this is not a problem. New ones have plastic boxes mount directly to carb with no external supports. They will work no problem.

Main question was what holes on carb do and what fuel lines do. I just need to know what is #1,2,3,4 and which way this carb should be oriented.
I've seen some guy on Youtube did something similar.

Rivets said:

Please post all the engine numbers. My boss is an old Stihl guy and I would like to see if he has any of the parts you need. He has tons of old parts both new and used.

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FS80

Serial on a photo. I have old carb out, see it on picture in original post

I would like to hear what he says. This unit looks very very sturdy, I do beleive it will last long time and making adapters to mount modern carb is probably good idea. I need some project anyway

#1 is the fuel intake from the tank, it goes to the filter dangling to the bottom of the tank.

#2 is the return from the purge bulb back to the tank, on your old version it just went to the grass in your yard, the govment made them return the
fuel to the tank several years later.

#3 is your impulse port that goes to the fuel pump side. You could buy an air filter assy off of a fs45 pretty cheap that would work.

What is hole #4? I don't have anything on a engine cylinder..

It goes to nothing on this model.

The carb can run at any angle.

Got it. But just curious, what is this hole #4? Where does it go on other models?

I don't know, if there is a hole there, it is plugged internally.

Did a little research with my boss today and found out the the Stihl TK carb and a Shindaiwa T25 carb take the same carb rebuild kit. The Shindaiwa rebuild kit number is 9990925, which is still available. He says he has a couple of the TK carbs around, but I didn't have time to look through the inventory. Will get back to you when I get time and find something.

Rivets said:

Did a little research with my boss today and found out the the Stihl TK carb and a Shindaiwa T25 carb take the same carb rebuild kit. The Shindaiwa rebuild kit number is 9990925, which is still available.

Click to expand...

I already tried that kit, no go. It runs, as I mentioned, but overflows. It has bad internal valve (non-serviceable)
Replacing carb only makes sense if it's brand new..