Stihl carbs??

Dashunde

LawnSite Senior Member
Location
St. Louis, Mo
Those who know, riddle me this... exactly what carb part keeps failing and caused my BG85/FS80/FS90/FC110/HS45(twice)/Dad's FS55 and now his BR200 to all suddenly idle fine but bog when the throttle is opened??

I've fruitlessly disassembled every single one and sprayed them out with carb cleaner, never any luck. The seemingly sudden on-set of the problem always tricks me into thinking it has a clogged port/needle (I'm dumb AND stubborn).

I usually just buy a fresh complete carb.. rebuild kits seem to cost nearly as much, so.
 
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Dashunde

LawnSite Senior Member
Location
St. Louis, Mo
How old are machines....2 stroke
Various ages - Mostly 2005 on up, Dad's FS55 is ~3-4 years old and his BR200 is ~2 years old - the relatively new blower is the one that really irritates me... worse yet, its kept at the lake and drinks only zero ethanol marine fuel.

Meanwhile my old FS55 from 2001 has never needed anything (that I recall).
 
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Dashunde

LawnSite Senior Member
Location
St. Louis, Mo
Have you ever checked the exhaust?

Running rich can be caused by obstructions on either end.
They're fine in that regard, after break-in I lean my 2-strokes a bit til' they sing proper.
No oily goop on the pipe/screens, no carbon on the plugs, no white spots either, just dry and gray.

So what is it about the Zama's that fails? Diaphragm or ?
Is there a good cheap aftermarket/amazon kit for them?
I dont mind a quick rebuild, even a pre-emptive one, if its cost-effective and works.
 

That Guy Gary

LawnSite Gold Member
Location
SW Idaho
I'm not sure, sounds like they don't like sitting around very much though. We use all Stihl handhelds and rarely need to replace carbs unless they get dropped on it and start running lean from an air leak.

I know a few users have bought cheaper aftermarket carbs on Amazon and Ebay and had good results though, I'd give it a try if our dealer didn't always have them in stock.
 

lawnboy dan

LawnSite Platinum Member
Location
north florida
I have not had good results with the cheap generic carbs on ebay for walbro carbs -havnt tried the zama ones yet. zama carbs are at least cheap tobuy so I just buy real zama carbs. stihl bought zama and lowered the price on carbs.
 

ARN Greencare

LawnSite Senior Member
I have not had good results with the cheap generic carbs on ebay for walbro carbs -havnt tried the zama ones yet. zama carbs are at least cheap tobuy so I just buy real zama carbs. stihl bought zama and lowered the price on carbs.
I tried one for an old two needle Zama and it would not pull fuel through the high side at all. Even trying to choke it. So I took it apart and the high side port was blank, they didn't finish drilling it out. So I was able to use the diaphragm and gasket on my old carb once I cleaned it. The fuel line grommet didn't fit my tank so I had to go to the dealer and get a grommet, and the fuel lines it came with deteriorated and literally broke in two at the tank Grommet in less than a month.

So no more knock off carbs from Ebay/Amazon for me...
 

lawnboy dan

LawnSite Platinum Member
Location
north florida
I got one once and no surprise-it didn't work. took it apart and found the metering diaphragm and gasket were installed in the wrong order. I corrected this and it still would not work.
 

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