Help on 020 avp carb. adjustment

Hi all, first post, although I've been reading for a few months now. Thanks for all knowledge you share here, and for making it so fun to read about.

Anyhow, I somehow got the (really bad) idea that I could actually adjust the carb on my old 020 avp myself instead of taking it to the dealer and have it done for me. All I originally wanted to achieve was to get rid of some of the bluish smoke and stop the chain from moving on idle. I should have known better, I really really should...

Anyhow, I was hoping the saw would behave just like most other saws seems to: "L", "H" and "LA" cw. to stop, then "L" and "H" about one turn ccw., adjust "LA" to satisfactory idle without chain motion, and then maybe fine-tune by ear. It's been explained here so many times, and it sounds easy...

Now, this does not seem to apply at all on this one, instead I'm several turns out on both "L" and "H" to have the saw starting at all. And "LA" has no impact on anything; I can have it from turned fully to stop clockwise to fully to stop counter clockwise and anything in between without the idle speed changing at all.

I feel really uncomfortable with this, plus at or near wot the saw will suddenly just die, just as fast as if I had pulled the switch. And the chain still moves on idle, but the smoke seems to respond to what I'm doing with the screws...

Could some kind person please just give me a hint about a starting point with those settings screws, since the "one turn out on all three" does not seem to be right for this one. Or is it maybe the other way around, that this is a sign on that the saw might wanna see a real professional for some more serious service?

not sure on that saw,i turn em(L,H) all the way in then 1&1/4 out(usually will start most of my saws).then i adjust my idler screw (LA)clockwise is in counterclockwise is out.Then when i got i idlin like a harley i start to tune the L,H screws.Hope this helps but im sure someone with more knowledge will be around any minute to correct me.Also try to search "madsens carb" on this forum.

Sounds like you have other problems with this saw, either an air leak somewhere or a grabby clutch with weak springs.

Larry

020 avi

Mccall,From you description I will try to assist. First off what is your elevation? Sweeden has some higher elevations. Anyway, from your suggestion about blue smoke, this tells me that your oil ratio may be a bit on the rich side.This could cause a lean mixture causing the saw to die at Wide Open Throttle. Another suggestion is that your gas filter may be plogged.At low RPM the filter has enough capacitiy to deliver the gas. However, at higher speeds it is restricting the flow of gas. Another possibility is simply that the gas tank vent may be plogged.A lean mixture will cause the chain to move at idle. Not a most safety related event.I would also do a compression check.
Welcome to the forum. Many wonderful people here. 020 is this not a Stihl saw? In Sweeden? Oh MY!!! Ken

is this same saw

http://www.arboristsite.com/attachment.php?attachmentid=1045&d=1021072786

this is a post from the thread where i found the pic

Originally posted by dbabcock

WRW brings up an interesting point about a partial vacuum being created causing the gas to boil at a much lower temperature than at normal atmospheric pressure. In addition to the vapor locking problem, the vacuum would cause the saw to run lean as well. Higher ambient temperatures would certainly exascerbate a potential boiling problem due to a partially blocked fuel tank vent. I can't imagine any saw being designed to allow gasoline to get so hot that it would boil at atmospheric pressure under any circumstances. I'd check out the fuel tank vent to see if it's plugged.


Here is link to thread maybe can help.
http://www.arboristsite.com/showthread.php?t=3656

Ax-man said:

Sounds like you have other problems with this saw, either an air leak somewhere or a grabby clutch with weak springs.

Click to expand...

You're probably right on the clutch/springs, I thought I'd just make sure idle speed were right before I started messing with the clutch, seemed to be the less costly end of it too...

kenskip1@verizo said:

Mccall,From you description I will try to assist. First off what is your elevation? Sweeden has some higher elevations.

Click to expand...

Yeah, we sure do, but I'm just above sea at about 175 ft.

kenskip1@verizo said:

Anyway, from your suggestion about blue smoke, this tells me that your oil ratio may be a bit on the rich side.This could cause a lean mixture causing the saw to die at Wide Open Throttle.

Click to expand...

The sticker on the saw says 1:25 so thats what I mixed for it. But it's the only thing I have that needs 1:25, all other are 1:50, so I don't make any larger batches of it, and when smaller quantities are mixed it's of course easier to make mistakes.

But maybe, with almost 35 years of oil technology developing since the saw were made, I might dare to try it on 1:50 as the others..?

kenskip1@verizo said:

Another suggestion is that your gas filter may be plogged.At low RPM the filter has enough capacitiy to deliver the gas. However, at higher speeds it is restricting the flow of gas. Another possibility is simply that the gas tank vent may be plogged. A lean mixture will cause the chain to move at idle. Not a most safety related event.I would also do a compression check.

Click to expand...

I guess that it's a good idea to change the filter anyway, so I will try to find one.

And with the vent, when you mention it, it seems it could be a perfectly good explanation to why it'just quits when consuming the most amount of gas. But since now and then, gas actually squirts right out of the lid when I use the saw, I would say air has the possibility to go the other way when needed...

kenskip1@verizo said:

Welcome to the forum. Many wonderful people here. 020 is this not a Stihl saw? In Sweeden? Oh MY!!! Ken

Click to expand...

Thanks! And sure, it's a Stihl. My father, who was a skilled car mechanic bought it new. Probably liked the double piston-rings and the German quality, since he also had a Ford, wich in many parts of Europe is considered to be a German car. I'll guess that surprises you Americans some...

However, my father died shortly after, but it was actually his choice of brand then, that made me go with Stihl when I bought my first own saw last year. That, and the fact that our local dealer, who mainly sells lawn movers and bikes, actually turned out to stock parts for a 35-year old saw when I needed a new av-rubber thingy for the saw...

l2edneck said:

http://www.arboristsite.com/attachment.php?attachmentid=1045&d=1021072786

Click to expand...

That's the same!

l2edneck said:

this is a post from the thread where i found the pic

Originally posted by dbabcock

WRW brings up an interesting point about a partial vacuum being created causing the gas to boil at a much lower temperature than at normal atmospheric pressure. In addition to the vapor locking problem, the vacuum would cause the saw to run lean as well. Higher ambient temperatures would certainly exascerbate a potential boiling problem due to a partially blocked fuel tank vent. I can't imagine any saw being designed to allow gasoline to get so hot that it would boil at atmospheric pressure under any circumstances. I'd check out the fuel tank vent to see if it's plugged.

Click to expand...

Hmm, with my earlier reply in mind I would still say that I'm not sure about this tank-vaccum-thing, but, yes, the gas in the tank boils from time to time, and not always during the most hard work. Actually, it scares the crap out of me when it happens. Gas should burn explosively inside an enginge, but it should not boil, and you should not be there seeing it happen at close range in either case...

l2edneck said:

Here is link to thread maybe can help.
http://www.arboristsite.com/showthread.php?t=3656

Click to expand...

Could there be another vent than the hole through the cap I should check? When the saw stops for me, it's not hard to start it again, but it takes a while to get the saw in starting position and maybe check if there's gas in the tank and so. Both things (especially opening the cap...) would give the vacuum time to disappear I guess.

The strangest of things I've noticed when it stops like this is that the saw likes me to completely close the air intake, as if it was a cold start. The only difference is that it starts and runs long enough for me to be able to open the air intake again before it stops, wich I never manage to do when it's a real cold start...

I went thru the same thing with my Dad's old 020.
Ended up rebuilding the carb, replacing all fuel lines & the impulse line. After the 2nd trip back the dealer finially got the carb adjusted correctly. I tried & could not get it right.
That old 020 is an excellent saw, but the carb adjustments are the most touchy I've ever run across.
I will NEVER touch the carb on that saw again.

Ed & happy to pay the dealer on this one.

maccall said:

Anyhow, I somehow got the (really bad) idea that I could actually adjust the carb on my old 020 avp myself instead of taking it to the dealer and have it done for me. All I originally wanted to achieve was to get rid of some of the bluish smoke and stop the chain from moving on idle. I should have known better, I really really should...

Click to expand...

I'm digging up an old thread here, my first actually, but since I believe I can offer final closure to it, I think it might be considered OK.

The saw runs fine now, but I'm unable to find the numbers on what's idle and max rpm for it, and I really like to check it out with my new EDT-7 so I don't fry it. They're not in the manual, and I can't find 'em on Acres Internet either. Could someone please help me with the numbers, it's for the old kind of 020 that's called 1114.

I will post the solution and try to get a few pics of it too when it's tuned, but I'll throwe you a hint in the meantime: Air leak, well, sure, I guess you could pretty much call it an air leak, but not your most common air leak, as in a broken seal or gasket or so, and remember that all that was really bad with it before I started to "adjust" the carb was that it idled so high that the chain was moving and that it also made some extra bluish exhaust smoke just as it was freshly started...

For the bored: Find the error:

So, some time later...

The saw is still running, and I was gonna post a short video of it, but while I figure out how to shrink the video to some more decent size I thought I should post a pic of the saw - naked! Or whatever you should call a 020 without its covering case...

Anyhow, on this picture, where nothing, apart from the case and parts that needed to be removed to get the case off, is otherwise removed. But being this far teared down you can actually see exactly what was the immediate problem with the saw. I saw it but it still took a while before really understood what I was seeing.

Now the only sad thing is I never took a video of how well the saw actually was running before I tried to adjust the idle speed. It would have been great fun showing it knowing what was wrong with the saw...

As an update: The saw ran very well, started easily, cut good (in any position) and idled. It just idled slightly high, so that the chain where running and it just did not seem to respond to any adjustment done to the idle speed adjuster. In fact, it didn't respond much to anything done to any of the adjustment screws. And at 1:25 mix it did put out some extra bluish smoke when started cold...

Now, on to that video shrinking...

Hey! This is my post #200!!! Thanks SawTroll!

So, As can be seen pretty clearly om the picture above the impulse hose isn't only leaking, or broke, but completely missing. You can see from the crud on the carburettor that it's been missing a long time too. :bang:

This saw was my fathers, and he was a mechanic by trade although his business was English cars, and it came into my hands sometime around -95. What happened to it after 1974, when my father passed away, and then I don't really know, other than that the saw was lend to one of my many uncles. If it was him or my father who did this repair I have no idea, and since this uncle of mine also passed away a few years ago this will remain a small mystery. I just wonder what kind of strange malfunction in the saw someone thought this was a suitable repair for...

This short video shows it in action. I didn't manage to shrink or convert it to a more usable format since my video editing software apparently does not deal with the QuickTime format, nor could I find and download anything usefull from the Net. Besides giving lousy quality to the pictures all software I could find really wasted the sound beyond repair. This is why there are some unnecessary lack of action at both the beginning and the end of the shot which I couldn't edit away.

Thanks for the help!

I will post a few pics of the saw when I get home from work too!

Here are the pics. It's a really nice looking little saw, and it hasn't seen too much use.





Look at this last one: The manual is printed on the back of the saw, and the yellow sticker that shows a corner to the right of the handlebar is the safety instruction. And all this in such a small package!