Carb tuning

[McCartman]

OK, I'm going to show my ignorance here, and I sincerely apologize to all you pros out there for asking this silly question.

I plan to do the muffler mod on my MS260. I bought this saw late this past fall and I'm quite sure it has an adjustable carb due to having three adjustment screws, correct?

My question is this - the three adjustment screws are labled "L", "H", and "LA". What do each of these adjust? Also, I have gone back through quite a few past posts on this forum and read about "limit plugs". What are these?

Thank you!

 

[kf_tree]

don't fret..........any second now skwerl will be posting a link to madsens carb tuning page.

 

[WoodTick007]

Hi BuddyBoy,

Try this link: http://www.madsens1.com/sawtune.htm

It worked for me. I am now a "MasterTuner".

GoodLuck!!

Ps. Pistons and cylinders for your saw can be bought on Ebay for about $65.

PsPs. I also have a link to make you a "MILLIONAIRE" in 30 days. Let me know if your interested. I have 6 more days until I should become one.

 

[davefr]

OK, I'm going to show my ignorance here, and I sincerely apologize to all you pros out there for asking this silly question.

I plan to do the muffler mod on my MS260. I bought this saw late this past fall and I'm quite sure it has an adjustable carb due to having three adjustment screws, correct?

My question is this - the three adjustment screws are labled "L", "H", and "LA". What do each of these adjust? Also, I have gone back through quite a few past posts on this forum and read about "limit plugs". What are these?

Thank you!

L = low speed jet
H = high speed jet
LA = Idle speed

Use the Madsen's link.

Your saw likely has caps that limit the adjustment range. You may need to remove these to get more range. If so, new caps will likely need to be installed to keep the screws from moving due to vibration.

P.S. You might want to see if Lakeside53 has any WT-194 carbs left. These were the non EPA fully adjustable 024/026 carbs. (no limiter caps or fixed jets to deal with)

 

[skwerl]

L and H are your low speed and high speed jets. Turning them in reduces the gas flow, turning them out increases the gas flow.

The LA screw is just the idle set screw. It adjusts the throttle stop. Screwing it in will raise your idle speed, backing it out will reduce your idle speed. After you've got the jets properly adjusted, set the idle so the chain does not spin and the motor does not stall.

All this is explained on the Madsen's carb page linked above, but I won't post the link just so I can prove Ken wrong this time.

 

[McCartman]

Thanks guys - much appreciated!

I know my way around equipment pretty well, but carbs have never been anything I've messed with much. Most of our stuff is diesel....

 

[McCartman]

I just did the muffler mod tonight. Haven't had a chance to run the beast much yet, however, I did try to open the high speed screw up a bit just to see how much range I had. Come to find out, the screw was turned out all the way - 3/4 turn from fully closed. Is there a stop in there somewhere that needs to be removed to adjust more if needed, or is it already all the way open? Will I need a different needle to get the mixture richer?

If there is a stop, how do I go about removing it? I downloaded the Stihl parts book, but do not see anything in the carb section referring to stops of any kind.

Thank you!

 

[timberwolf]

If it is the carb with the plastic cap, it can be screwed out, I found just a little forece sheered of the indexing stop pin on the plastic cap, I have run a long time with no cap at all, it may move on occasion, but always recheck the mix anyway.

will send a photo.

 

[West Texas]

If you remove the carb; http://www.giftsofwood.com/stihl_info.htm use this web site to download Repair Manual on the 260, you can see if the limit stops are 'visible', if so, just clip them off and this will allow you to open up the High Speed and Low Speed jets for better tuning "if it is needed."

If you don't see the limit stops, then they are inside the metal shroud coming out of the carb where the jets go into the carb. Now you have a horse of a different color; and, I'll let the guys on here who have worked on these, give you their expertise.

As a general rule, I find only the H jet needs to be opened up more, when making a muffler mod. The L jet primarily affects 'starting' the saw, although is does have 'some' effect overall.

 

[timberwolf]

Photo 1 Carb with caps, note hs cap is removed as well as plastic insert.

Photo 2 carb with no caps, note springs to keep the jets from moving out of adjustment.

Hope it helps.

 

[McCartman]

Thank you much, guys. Especially timberwolf - the pics cleared things up for me a great deal. I do, indeed, have the limit caps. Methinks I'll be able to handle it from here.