Stihl 034, 3 different ZAMA carbs listed????

Okie

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Was given a non -running Stihl 034, chain looks new, reported to be low compression.
I checked the compression as 140-150, removed muffler and piston/cylinder look great.
Dumped old bad gas from tank, and gave it a prime of mixed gas into carb throat and got a run in about 3 pulls, added good gas and got a idle run, idles good.
Problem: When I try to piss rev it bogs and I have to get off throttle fast to get back to idle low idle jet adjusts ok at around 1 1/2 turns out, H jet don't seem to change anything about the response hardly and trying to lean or enrichen the L jet don't help the bog any. Checked fuel line and filter as ok. Acts like starves for fuel when trying to piss rev.
I'm thinking carb or carb kit.
Pulled the carb and see ZAMA C3 and what appears to be 819 37A (not sure about the 8 (might be a S or ?)
and ZAMA Hong Kong on the top plate.

Could this be a OEM carb? (from Hong Kong)

When I went to looking at carbs it looks like a 1125 120 0606 or a 1125 120 0617 in the pictures. (at around $60)

I also see one that is a 1125 120 0615 with a snout that does not match mine. What's with the snout type?

Thinking of just using my ultrasonic and doing a kit to the existing carb first.
The kit for mine appears MAYBE to be a 1128 007 1065 or a ZAMA RB-31??
I removed the single screw plate end that Has the ZAMA Hong Kong and the screen is clean and the little diaphragm looked pliable.

Anyone had any good/bad experience wrestling with the carbs on the Stihl 034???
 
berrnard

berrnard

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I L jet is what regulates the mix at idle and “piss rev”. The H is for full constant theottle and speed.
Move idle screw to hefty rev and then adjust the L to highest rev and then back out 1/8th turn.
Then turn the LA back to a good idle to where the chain doesn’t spin but it doesn’t die after a full rev.


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Wood Doctor

Wood Doctor

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The L jet is what regulates the mix at idle and “pss rev”. The H is for full constant throttle and WOT speed. Move idle screw to hefty rev and then adjust the L to highest rev and then back out 1/8th turn. Then turn the LA back to a good idle to where the chain doesn’t spin but it doesn’t die after a full rev.

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I must admit that this advice from southern Indiana is excellent and a procedure that I often follow. The only time it may fail is with plastic limiters installed on the carb that drive me and everyone else nuts.
 
cuinrearview

cuinrearview

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I'm fighting one of these carbs with similar issues. The second one that I rebuilt isn't pulling fuel at all. I screwed with it for over an hour tonight. I'm over it, time for a different brand of frustration; the Lions are about to come on.
 

Okie

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The “snout” is for the newer compensating carbs, though you can just switch the cover plates with no issues.

Clue me in on switching cover plates to use the snout type carb? Do I get a different metal intake gasket that goes behind the carb or ???? (I'm not familiar with cover plates and compensating carbs)
I see a snout type carb 1125 120 0615 for about $20 I could maybe just run it as a test later if necessary.

These replacement carbs that look like mine in pictures are 1125 120 0617 @ $60 and don't want to throw that much at this saw even though I'm trying to get it going for myself.
 

Okie

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I L jet is what regulates the mix at idle and “piss rev”. The H is for full constant theottle and speed.
Move idle screw to hefty rev and then adjust the L to highest rev and then back out 1/8th turn.
Then turn the LA back to a good idle to where the chain doesn’t spin but it doesn’t die after a full rev.


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Yep, that is correct but this carb won't accept the correct adjustments and go. (I'm familiar with what you are saying in the adjustments.
 

Okie

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I'm fighting one of these carbs with similar issues. The second one that I rebuilt isn't pulling fuel at all. I screwed with it for over an hour tonight. I'm over it, time for a different brand of frustration; the Lions are about to come on.

This one is pulling fuel, starts and idles good. It acts like the H jet side is blocked, but every once in awhile I can make it start reving little bit but if I stay in it full throttle it it will start smothering and die. Choke and it will re-go and idle great. Bog when throttled. I pulled the tank vent off and no go, pressure tested the fuel line as ok, fuel filter clean. Acts like a bad carb.
 
drf255

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That’s an oem carb.

Did you vac test the saw? Did you install boot correctly? Why do you need to be 1.5 turns out to idle? You may be puddling fuel in the intact tract and when you pull the trigger, bog city.

You can get the $20 AM carbs and swap the cover. I’ve been told that they are made on the same assembly line as the OEM Zama’s. In fact, up till around a year ago, the AM carbs had “Zama” cast into them. C3A is still cast into the side.

There are many carbs offered on the 1125 model line. A few different jetting options, even though they look the same externally.

The 034S also cane with the troublesome, but better performing, Tillotson 43b.
 

Okie

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Running/cutting in the wood and oiling good NOW.

Went out this AM and while the carb was off snugged up the top and bottom carb screws, set both jets to 1 turn out, no go on H, just bog. Would idle good if I immediately got out of bog, if I stayed in it would appear to run out of gas, choke and re-start easily and idle ok.

Looked behind carb at very dirty manifold boot and when I started to inspect the manifold boot closer the little pulse line fell off the back of the plastic carb adapter nipple. I snipped little bit off the end and got a snug fit and all ok. The pulse line was not making good connection causing carb pump to starve at high rpms.
The carb adjusted normally and very critical on the L for correct idle at 1 turn out (1/8 turn will change idle speed)

Can anyone post a link to download a 034 owners manual?
Mainly want to see how to adjust the oiler and when all else fails check the owners manual.;)

and thanks for the help.
 
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