tuning question

[Pilsnaman]

I have been using two cycle engines for years now and always tuned them myself. Lately I have started to question my tuning technique and figured you guys could help ensure I am doing it right. First, I turn in the high and low screws all the way and unscrew them around 1 turn. Then I start the engine, let it warm up, and begin with the low adjustment. The low is adjusted so it idles smooth but doesn't seem to race. Then I adjust the high by going full throttle and easing the screw either in or out, depending on which direction causes an increase in RPM. As soon as the engine is running at what seems to be its peek and is smooth I screw the high adjustment in until it just begins to burble a bit, which I assume is what people mean by "4 cycle." The acceleration is next with adjustments to the low screw, ensuring a smooth pick-up. Last is the idle speed, adjusted to keep the engine running but below chain engagement.
If any or all of this is wrong please let me know, thanks.

 

[buck futter]

You got it although when your done you want to make sure it revs well from an idle to wot, also some carbs have a dependant jet system meaning if you fool with one jet it may have some impact on the other.

Buck

 

[ctiedt]

I asked some questions about tuning the carb myself and got a lot of help. One item I found to be really helpful came from Cut4Fun
http://ilvirtualforest.nres.uiuc.edu...sawburetor.htm

It goes through everything and in reading your post, it looks like you pretty much do the same thing....

 

[Kneejerk Bombas]

Madsens site has the best tuning information on the web. It even inculdes some sound bites to let you hear what it sounds like.

 

[Elmore]

H screw

Correct me if I'm wrong but turning the high speed adjustment screw counter clockwise will make it rich so shouldn't you finish your high speed adjustment by turning this adjustment screw counter clockwise not in.

 

[Pilsnaman]

Correct me if I'm wrong but turning the high speed adjustment screw counter clockwise will make it rich so shouldn't you finish your high speed adjusment by turning this adjusment screw counter clockwise not in.

I followed the site Cut4Fun put up and you are correct that it should be rich. Seems I have been doing something wrong and loosing a lot of power because of it. Thanks guys and if there is anything else or any little tricks please let me know.

 

[racereric]

Turning the screw in clockwise closes the conical orifice leaning out the fuel/air mixture. Counter clockwise will richen the mix.

 

[donnyman]

Im with elwood.Turn your high speed jet out untill it 4 cycles not in.Later Don.

 

[RaisedByWolves]

I allways start tuning with the high speed needle due to the fact that on some carbs all of the fuel passes this needle first then goes to the idle circut.

This is what causes the situation buck futter is talking about.

 

[Lakeside53]

I allways start tuning with the high speed needle due to the fact that on some carbs all of the fuel passes this needle first then goes to the idle circut.

This is what causes the situation buck futter is talking about.

It does? Not on the carbs I work on... I always set the idle/L first, then worry about the H.

 

[RaisedByWolves]

It does? Not on the carbs I work on...

Yes, On SOME it does, mebbe not on Stihl carbs, but I generally work on a wide variety of equipment, new and old, two and four stroke, and have found it to be good practice.


Opinions may differ however.

 

[Pilsnaman]

Thanks again for the help. Corrected my mistake on the high side and man what a difference, its like a whole new saw...Life is good!

 

[MikeInParadise]

I asked some questions about tuning the carb myself and got a lot of help. One item I found to be really helpful came from Cut4Fun
http://ilvirtualforest.nres.uiuc.edu...sawburetor.htm

It goes through everything and in reading your post, it looks like you pretty much do the same thing....

Corrected link
http://ilvirtualforest.nres.uiuc.edu/harvest/timstips/sawburetor.htm

 

[manual]

I removed the screen opened the exhaust hole a little more removed the limit tabs on the carb adjusted the carb to what I thought sounded good.
My saw starts good runs faster. But seems to run on after I shut it down.
What I did I do wrong?

 

[bugfart]

You either have deisel like compression or a faulty connection to ground at the on/off switch.

 

[manual]

Thanks Bugfart, I'll Take a look at the switch. I have a ohm meter.
Sounds like a good place to start.

 

[RaisedByWolves]

Excessive carbon buildup can also cause this.

 

[manual]

You either have deisel like compression or a faulty connection to ground at the on/off switch.

Right on the money found ground wire to switch to be loose.
Was not easy getting to the switch on my Jonny Red. But worth it.
Got some Grade oaks to cut down. as soon as I get my tractor ready.