stihl 034 super zama carb adjustment

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oaky

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hello

i have a stihl 034 super and i've noticed it sometimes dies after a long cut (with fuel in the tank)
so i decided to see what the settings where at on the carb.

the high screw was turned in quite far, somewhere between half turn - three quarters open.
and the low screw seemed a little over a turn.

so i put them back to one full turn. got the idle going at 2700rpm. the low speed screw I got pretty close, itll still get pretty close to stalling out after a cut, hard to tell though if its starving for fuel or partially flooding it. but i just about found the middle ground.

the one thing i didnt get is that at one full turn on the high speed screw at WOT its rpms are at about 9500-10000. then when i lean it just a little bit ill WOT around 11000-11500 then rev itself up to 13750-14000rpm. are the carbs limited?
cutting wood with it one turn open doesnt feel as good as it was before.

carb is a zama and probably hasnt been rebuilt in quite awhile. impulse hose looks good.
 
No the carbsnot limited. If it hasn’t been off for awhile a ultrasonic cleaning wouldn’t hurt and a kit. On the supers and 36’s leaning out has been an issue for me.... ported are even worse.
Try cleaning and a kit and see what it does. Some carbs are are very touchy setting them and pretty normal.
 
any theorys on why it would hold steady at 11000 then all of a sudden lean up to 13500.

ill look into carb kit, think its the C3A-S31A
 
pressure tested the carb and it holds pressure just fine.
could there still be an issue with it? doesnt look like its ever been opened.

i might just pressure test the case back sure a seal didnt go.
i was using the saw for making fence posts with a mini mill for a day or two.. maybe something happened.
 
Looks like you found your problem, but I'm beginning to think those Zama carbs can be a little odd.

My old 55 Husqvarna has a Zama Carb. I bought the saw new in 1997, and as far as I can remember, the carb's never even been off the saw, and it has always ran perfect.

Anyway, a week or so ago I thought I'd check the carb adjustments, just to see if they needed any fine tweaking. (Just bored and looking for something to do)

I found that turning the H or the L screws in either direction didn't seem to have any effect at all. (I'm talking a turn or two either way!)

But strangely the saw still runs great, idles great, and seems to have the perfect amount of 4 stroke flutter at WOT, just like it always has.

I'm stumped?

Not sure if that's normal with these Zama carbs or what?
I'll probably get a new carb eventually, but it's just strange that it runs perfect, regardless of where the adjustment screws are turned.
 
wow! a turn or two each!
thats interesting because I just adjusted a carb on a husq. 50 today with the same type of results, didnt look to see what type of carb, but i left them near stock settings..

but my stihl's 034 zama does respond quick to an even a 1/16 of a turn, maybe its a certain type of model.
i have heard zamas being quite odd as well, but the tillotson for the stihl 034 is hard to find.
 
Yeah, I'm not sure what carbs were on the 50's, but it's interesting that you seemed to have similar results.
I did the same thing with mine ... since turning them seemed to have no effect, and it runs fine, I just put them back to stock settings, and walked away from it.

I have an 032 with a Tillotson. It's very responsive to adjustment too. Luckily so far only thing I've ever needed for it was a diaphragm.
 
alright! so its not the the seal.
theres these two screws that hold down the oil pump around the seal, leaking past the screws even with the pump installed.

bearings not sealed.. so maybe ill just throw some thread lock type material on the screws and some tiny gaskets on to seal it up
 
threadlock sealant worked great but i still had late timed revving issues.
threw in a carb kit now runs great with no issues. have it tuned to about 12700-12800max rpm and holds steady
 
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