Stihl top handles

[Dave Shepard]

Got the carb kit today and it's for a Zama, I've got a Walbro. The Walbro has no high speed jet, how the heck do you tune the dang thing?

 

[SkwerI]

The Stihl experiment with fixed main jets was an abysmal failure. Buy a replacement carb that is NOT a fixed jet model. either pull up your IPL or else go to the dealer and scroll through and find an older or newer carb number that is fully adjustable.

The fixed jet carbs can be tuned by opening them up and replacing the jet with larger or smaller jets, but they are $5 each and usually special order. Completely worthless. :roll:

 

[Al Smith]

You don't ,just set the idle .That's all you can do . Fixed jet carbs were made for one purpose--so you can't burn up a saw from running it lean .They kinda suck .

 

[Dave Shepard]

Yeah, I was thinking I'd go the replacement route. Fixed jet seems to big brother like too me. As well as totally freaking retarded.

 

[Dave Shepard]

Al, maybe I just need to keep letting more air in until it runs right.

 

[Al Smith]

Actually a lot of manufacturers used them at one time or another .Poulan Stihl ,Homelite .Even the classic 125 Mac had a fixed jet on a few . They didn't work well at all .

In more modern times they tried to eliminate lean run and EPA issues by using limiter caps instead of fixed main jets .Thank heavens those can be bypassed .

 

[sotc]

so i built 1 saw from 2 last night. put some gas in and fired it up and it idles really high. so i screwed both carb screws all the way in and backed out 3/4 turn. still really high idle. my guess is airleak but i wanted to run it by you guys and see what you thought

 

[Dave Shepard]

What about the third, non-jet, screw?

 

[sotc]

no 3rd screw on this one

 

[Dave Shepard]

The IPL shows a third screw in the base cover of the carb. Both the zama and walbro's have them.

 

[Dave Shepard]

Do you have the Zama or the Walbro? The walbro does not have a high speed jet. Here is a pic showing the idle screw in the base of a Zama.

 

[sotc]

lemme check my ipl and see where

 

[sotc]

thats not the one i have, lemme go grab a pic

 

[Dave Shepard]

That's the walbro. You only have low speed jet and the idle jet. If you can't get it to idle with those two screws, you'll have to talk to Al.

 

[Dave Shepard]

Try backing out the low speed jet to enrich the mixture, and thereby lowering the idle speed.

 

[sotc]

i had trouble with it on the other saw, was thinking id replace it soon anyway

 

[Dave Shepard]

I'm replacing the walbro on my 20t for that reason. I want to be able to tune the top end.

 

[sotc]

ok ill try that tomorow

 

[Chisel Tooth]

Single screw is a fixed jet carb, you can only adjust the low speed.
2 screw is adjustable on both ends, make sure that your butterfly is closing, and that the idle screw is not into far. This is the screw that controls how far the butterfly stays open.
Check the trigger movement and make sure it is smooth, remove the air filter and watch.
I have all the settings in a book down in the shop for all the Stihl products, depending on the saw the settings can range from 1/4 to 1 1/4 turns out from the seated postion. I can double check, to make sure if you like.

 

[sotc]

id love that, thanks

 

[Chisel Tooth]

Which saw is it and do you want it tonight or tommorow?

 

[sotc]

combination of an 020t and a 200t. when ever you can, no big rush

 

[Chisel Tooth]

OK, no problem, I'll get the info in the morning and let you know.

 

[Al Smith]

If you can't get it to idle with those two screws, you'll have to talk to Al.

Rocky found this little tid bit .

If for some reason the butterfly gets turned the little slot becomes misaligned with the idle jet and they won't idle .

 

[SkwerI]

Willie, the bigger bottom screw is the idle stop set. It doesn't affect mixture at all but it holds the butterfly open to increase idle speed. If you have it set at 1 turn out from bottom then it's wrong and will force the saw to idle too high.

And I told you before not to use that stupid carb with the fixed high speed jet. It will eventually cause problems.

As a refresher, here's the carb adjustment page again.
http://www.madsens1.com/saw carb tune.htm