older 026 max RPM's???

[361 STIHL]

I have an older model 026 (1993) which I purchased used but was fortunate enough to have the original sales receipt and owners manual included with the saw. In the carburetor adjustment section of the owner’s manual the Max engine speed with cutting attachment is listed as 12500 RPM. In the specification section of the same owners manual the max speed listing is for 13000 RPM. In the service manual which is dated 1999 the listing is for 14000 RPM.
I would like to get the carb set up without damaging the saw by running it to lean just not sure which speed is correct for this year model saw. Any help you guys could give would be appreciated. Not sure if this matters but I am currently running a 18” bar and .325 chain.

 

[fishhuntcutwood]

026 is a fast, easily revved saw.

Where's Lakeside?

 

[Crofter]

I would try the 13,000 figure and check spark plug for a nice tan colour after a fairly hard run. If it is on the dark side, you could go a little leaner (to a higher rpm.) Make sure your intake filter is clean when you adjust and clean it often. They have a very puny amount of filter area and plug quickly. A 14,000 WOT with a clogged filter would likely translate to a very lean mixture. Err on the rich side!

 

[Lakeside53]

I'm here Jeff - sorry, slept in


My guess on the 1999 number verses the 1993 number is just EPA emissions.. BOTH saws are rated at the same HP, but they wanted you to run leaner in 1999..

Pretty much like Crofter stated except I don't bother about checking the plug color. I just set all of them them at 13,500-13,750 (we're talking about a HAIR of adjustment from 13,500 to 14,000 anyhow...and that hair can just as easily take you to 14,500... so I'm slight conservative) with A CLEAN air filter. Any further filter blockage just enrichens the mixture. Never set WOT on any saw with a dirty filter that's just asking for trouble when you clean it one day and forget to reset the carb. Often I take off the filter to set the WOT, then look at the change once its back on. If it's clean, the drop is small. Another suggestion : change out the FUEL filter for the larger capacity filter used on MS200T etc.


An interesting observation over the years: if the 026 carb is working correctly and the saw is in good shape, 1 turn out on the H screw almost alway translates to 12 - 12,500rpm...
A tiny adjustment (on WT22 or WT194) is all it takes to get it to 13,500. Slightly more of a turn on the WT426 as H screw only varies a smaller portion of the fuel flow.

If you have the inclinaton, time you cuts at 1 turn out, then at 13,000, then at 14,000. May not be a as much variation as you think...

 

[Jackman61]

Crofter,

I'm no expert on the workings of the Stihl intellicarb, but a clogged air filter usually translates to a rich running condition. The danger would be to set the carb up with the clogged air filter, then clean the air filter. More airflow would produce a lean operating condition. Is there something special about the intellicarb that defies this logic?

I would set with the tach at 12,500 and try it in the cut, then repeat at 13,000 and see which performs to your liking.

 

[Lakeside53]

Crofter,

I'm no expert on the workings of the Stihl intellicarb, but a clogged air filter usually translates to a rich running condition. The danger would be to set the carb up with the clogged air filter, then clean the air filter. More airflow would produce a lean operating condition. Is there something special about the intellicarb that defies this logic?

I would set with the tach at 12,500 and try it in the cut, then repeat at 13,000 and see which performs to your liking.

The intellicarb obeys the same laws of physics as the standard carb! It mixes fuel based on how you set the H screw, but compensates for a blocking filter within a small range.

It works by leaning out the mixture as the filter gets blocked (within small limits) due to a drop in relative pressure as sensed by the metering diaphragm, but doesn't enrichen it if you start at max with a blocked filter and then clean it.

 

[Crofter]

Generally speaking restricting intake will richen the mixture; it will also reduce the WOT speed. Now if you are trying to get the clogged saw back up to hit the higher rpm with the restricted air flow you may have to lean out the mixture to achieve it. A certain RPM is no guarantee of a certain degree of air / fuel mixture. It is only an indicator of what should be good PROVIDING all components are in normal condition. Two important ones being intake filter and exhaust screeen. They have to be clear or I think you will need a leaner mix to hit a given RPM. That is probably debatable but it IS important to have the filter and exhaust clear before setting mixture by RPM.

 

[Lakeside53]

Crofter is 100% correct... we're all in violent agreement, but just saying it differently!

 

[361 STIHL]

Thanks guys that clears that up, I do have one more question along this same line I have not been able to find an answer to doing a search. As you probably have guessed I also have a 361 which is stock other than a muffler mod. I set it up to 14000 RPM’s at WOT with a 20” bar running a 3/8 7pin sprocket, this ran so good I decided to try a little taller gear so I fitted a 3/8 8 pin sprocket. This dropped the WOT RPM reading down to the mid 12000’s, I have not retuned the carb yet to bring the RPM”s back up but assume this is the correct thing to do? Which brings me to my question, if a longer bar and chain combo means retuning (leaner) to bring the RPM”s back to spec at what point do you cross the line and begin to run to lean? Stihl says the 361 will run a 28” bar, would I still set it up to run 14000 RPM”s at WOT without leaning it out to much?
I know the 361 running a 28” bar has been discussed quite a bit, I am not trying to revive this discussion just using the far end of the spectrum to try and understand the relationship between engine load (bar and chain length) and its affect on fuel mixture when trying to tune for max RPM”s and power.
I hope I am not being to complicated just hate to ruin a good saw trying to use a tach correctly. Thanks for all the help!!

 

[Lakeside53]

Thanks guys that clears that up, I do have one more question along this same line I have not been able to find an answer to doing a search. As you probably have guessed I also have a 361 which is stock other than a muffler mod. I set it up to 14000 RPM’s at WOT with a 20” bar running a 3/8 7pin sprocket, this ran so good I decided to try a little taller gear so I fitted a 3/8 8 pin sprocket. This dropped the WOT RPM reading down to the mid 12000’s, I have not retuned the carb yet to bring the RPM”s back up but assume this is the correct thing to do? Which brings me to my question, if a longer bar and chain combo means retuning (leaner) to bring the RPM”s back to spec at what point do you cross the line and begin to run to lean? Stihl says the 361 will run a 28” bar, would I still set it up to run 14000 RPM”s at WOT without leaning it out to much?
I know the 361 running a 28” bar has been discussed quite a bit, I am not trying to revive this discussion just using the far end of the spectrum to try and understand the relationship between engine load (bar and chain length) and its affect on fuel mixture when trying to tune for max RPM”s and power.
I hope I am not being to complicated just hate to ruin a good saw trying to use a tach correctly. Thanks for all the help!!

For a correctly tensioned chain, lubed sufficiently, I never see much change in WOT.... no matter what (reasonable) bar length. Can't say I've ever changed a 7 to and 8 and re-tached it, but I can't image it would load up the engine that much...It doesn't take much power just to run a chain... Heck, I can run them around the bar with one finger.

To answer your quesiton, I wouldn't go reajusting the carb leaner until you've figiured out what is going on... In any case, timed cuts are all that really matters, not the actual WOT speed, Make some cuts with both sprockets, let us know the results.

 

[THALL10326]

Longer chains do reduce the WOT rpms from shorter chains on the same saw. If you put a tach on it you'll see a change. How much, you'd be surprised. Example would be to take a weed trimmer. If you snipped off just one inch of the trimmer line the motor will speed up 1000 rpms believe it or not. I've tached a few Stihl's by going from 20inch to 24 inch and have lost as much as 1500 rpms at WOT with the longer chain. Get a tach and try it. Can't say I ever tached the differance by changing sprockets but I'll make a note to try that.

 

[Lakeside53]

Longer chains do reduce the WOT rpms from shorter chains on the same saw. If you put a tach on it you'll see a change. How much, you'd be surprised. Example would be to take a weed trimmer. If you snipped off just one inch of the trimmer line the motor will speed up 1000 rpms believe it or not. I've tached a few Stihl's by going from 20inch to 24 inch and have lost as much as 1500 rpms at WOT with the longer chain. Get a tach and try it. Can't say I ever tached the differance by changing sprockets but I'll make a note to try that.

The weedwacker is different... but you're right that it changes the max rpm significantly. However, the string represents a substantial load due to the air resistance. The max rpm of the weedeater is always set at the required string length which is pretty much full rated power. Want to seize weedeater by overheating the engine? just add a few inches to the string. I get weedwackers in where the guy has removed the cutting blade to gain a few inches of cut, and now it just keeps "quiting" after 10 minutes of use... and you can't turn it over for a few minutes after that. great...

As for saws, interesting... which brings back the question of how long a bar should you add and keep chasing that "wot" setting. I think I'll spring that question on my Tech contact at Sthl, just for grins. I can see it affecting a small saw, but wouldn't have though it affected a 361 as much.

I'd say the obvious answer is be conservative, use a mid-size bar for tuning, and be a little richer than required, but that answer will drive the power hungry crowd on AS crazy.

If it wasn't pissing down outside, I'd go try the sprocket/bar test right now. So I'll just sit in front of the fire and have a couple instead

 

[THALL10326]

The weedwacker is different... but you're right that it changes the max rpm significantly. However, the string represents a substantial load due to the air resistance. The max rpm of the weedeater is always set at the required string length which is pretty much full rated power. Want to seize weedeater by overheating the engine? just add a few inches to the string. I get weedwackers in where the guy has removed the cutting blade to gain a few inches of cut, and now it just keeps "quiting" after 10 minutes of use... and you can't turn it over for a few minutes after that. great...

As for saws, interesting... which brings back the question of how long a bar should you add and keep chasing that "wot" setting. I think I'll spring that question on my Tech contact at Sthl, just for grins. I can see it affecting a small saw, but wouldn't have though it affected a 361 as much.

I'd say the obvious answer is be conservative, use a mid-size bar for tuning, and be a little richer than required, but that answer will drive the power hungry crowd on AS crazy.

If it wasn't pissing down outside, I'd go try the sprocket/bar test right now.
So I'll just sit in front of the fire and have a couple instead

You be correct there Lake. I got plenty of pistons and cranks ruined cause the man said that guard gets in the way. I always say yep it sure does but I told ya not to take it off, now look what ya got The saws I tached changing chains was my own 036 and 034. I was surprised it changed that much for I didn't think it would change at all but it did. As to why it could be more than just chain, the bar rails may have been ruff or dented on the long bar, can't say for sure cause I didn't checkem..