Stihl top handles.

I also generally do what Larry suggested, but also blow out the passages with a compressor. I've read that a check valve can be damaged by air pressure. Been too lazy to learn where a check valve might exist, and whether all carbs have them.
 
That little Zama is one carb I can't explain because I have no idea what lurks under that damned triangle shaped welch plug .Eddie tried to explain it but I got lost in the first turn .

Eventually as I'm sure will happen one of my 200s' will take a fit and then I'll delve into it .
 
I dissected a Tilly HU carb once to see what this mystery check valve looked like. All it is a plastic little ball about the size of a BB but a little smaller. I can't remeber where it was located in the carb. I really don't see how a check valve can cause problems but I am sure in some way it can.

I think you can get a major repair carb kit from Sthil that has this check valve in it. I remember someone over at AS talking about this. I don't know how true this is.
 
I did a little experiment this morning with my erratic lean running MS200. From what I learned 27 yrs ago when I built my Yamaha YZ bikesaw, I noticed lots of air bubbles flowing into the bikesaw's carb through its clear fuel line. I stuffed the bikesaw's fuel tank with copper pot scrubbers [Kurly Kates]. End of air bubble problem.
So I stuffed my MS200 fuel tank the same way, with the fuel line filter pickup locked in one position I was careful not to cut with the rewind housing down or bar up in the air so the saw was getting a constant fuel supply.
My results was the saw ran better. Now from this test I figure with the MS200's solid mounted fuel tank to engine, vibration is foaming up the gas mixture right to the carb. With air in the carb where air shouldn't be continual oxidization may harm some of the internal parts along with a lean condition. Now why didn't my old 020 have the same problem? From what I can see the MS200 is now putting out more h.p. and more vibration.
My Husqvarna 338XPT has its fuel tank seperated from the engine vibrations through its anti- vibe setup. Also you'll notice the new Husky T540XP has the fuel tank isolated too.
So my advice to Stihl is, build your next new TH saw with an isolated fuel tank.

Willard.
 
I think I would probably replace the AV mounts before attempting all that. :?
Or seeing as how the carbs are the weak link, perhaps test the saw with a known good carb off another saw.
 
I've got three and one with a new carb is still running weird when it gets down just a little ways in the tank. Problem is with having three I just set it aside and figured I'd look at the fuel line one of the these days. Filters, plug, settings, basic things like that are never an issue for my saws
 
squisher said:
Interesting. Do you think it would get progressively worse as the saws anti vibe wears?
Click to expand...
No effect -The 200's av only isolates the handles and carb only, the fuel tank is solid with the engine.
Huskies tank carb etc are isolated= best setup.
Willard
 
they still do it when new, the 1st 200 demo I tried 8-9 yrs ago ran like a PoS, the 2 I bought later ran the same brand new, dealer just kept changing the carbs while on warranty. Then you find a good carb and it can go for yrs.
Willard.
 
My three ran flawlessly up to about 1 and half years old. Flawlessly, all three of them. two I've since replaced carbs, and one I've basically just set aside. Now one of the new carb ones is still hastling me as previously described. Zero issues up to that point though. So I never experienced any fuel issues new.
 
I wished I kept my old 020s, I never had a problem with them maybe their carbs might do better on the 200. But I still think there is a foaming issue with vibration in the fuel tank. Maybe I should try a clear fuel line on the 200 to see if there is air bubbles at WOT.
Willard
 
I gotta look at that bastard that's still giving me problems. I will say this, I've had more issues with them then any of my other 8 or 9 stihls, but I'm not about to stop running them.
 
squisher said:
I gotta look at that bastard that's still giving me problems. I will say this, I've had more issues with them then any of my other 8 or 9 stihls, but I'm not about to stop running them.
Click to expand...
I love my 200 too, will probably buy another soon. The last 020 I had looked identical to the MS200 except it didn't have flip caps and ran a little slower.
Willard.
 
Lol flip caps. I made my new guy run my old(ish) 46 which has real caps on it and he was immediately running for a bar wrench. I lol,ed and told him he better not touch no bar wrench to my caps and showed him how to press against his thumb to undo a tight oil cap. I hate the new caps, absolutely hate them.
 
Willard didnt the 020T saws have walbro's on them. Just something people might look into for a swap.
 
Cut4fun said:
Willard didnt the 020T saws have walbro's on them. Just something people might look into for a swap.
Click to expand...
Yes they were Walbros Kevin. As far back as I remember the 020s had Walbros since the late 1980s , the earlier models may have had them too. 020 introduced in 1971.
Willard.
 
I was just talking about the later 020T that was just like the 200T but with old screw on caps. Just wonder if that carb could be a direct replacement for the pos zama's stihl is putting out.
 
Gotcha, good point. I can't remember what my newest 020 had for a carb.
Our local Stihl dealers would have all the answers. Some saw models in the same year may have 3 different models of carbs, depending on the production run.
Willard.
 
Just dug out my first MS200's owners manual dated 2000-01 and on page 5 it says some MS200 models had the screw type fuel/oil caps. Mine had the flip caps and flush slotted airfilter cover knob. I sold this saw and my old 020 [1996] to a tree service buddy in the big city.
Just some info that might help track down when Walbro carbs were last used. Nothing in the manual of what type of carb.
Willard.
 
HolmenTree said:
Just some info that might help track down when Walbro carbs were last used. Nothing in the manual of what type of carb.
Willard.
Click to expand...

I'll check my IPL's and Service Manuals when I get time.
 
The older Zamas made in Japan were good carbs. I just figured out my 1996 020T had a Zama C1Q-S16,A . The 020AV from 1980s early90s had a Walbro. But the old 020AV was a different saw design altogether from the newer 020T. So stick with this Zama to fit the MS200T.
Willard.
 
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