That adjustment is for idle speed. If there are any other adjustments, they are well hid. I watched the YouTube video listed below and looked as he rotated the carb and did not see any adjustments other than idle speed.
https://youtu.be/gUyOpYa25cM
Stihl 170 Chain Saw Carbon problem
- Thread starter chzuck
- Start date
https://youtu.be/gUyOpYa25cM
Possibly too long idling. I am going to pay more attention this time and see how long it takes to clog up.
Your saw is running much to rich , these screens normally need cleaning perhaps once a yr . if you use your saw perhaps 100 hrs a yr. Most consumers never use their units than much . Amsoil Sabre is the best Premium Grade Synthetic oil made . Opti -2 or Stihl Ultra are also premium oil . Pull you spark plug and I would bet it is dark brown or black , indicating much to rich of oil ratio . 50:1 is more than adequate for your model . The carb is adjustable once you remove the limitor caps depending on which yr your saw is will determine which adjuster tool you will need , Pacman , splined hex ..etc ! These tools are onine for 2-3 bucks or you can slot yours with dremel and use a small slotted screwdriver to adjust you jets to lean out your high speed jet .
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OK, I will say this again, this carburetor has only one adjustment - idle speed. I used and am using Stihl Ultra at the recommended amounts. I took a look at the carburetor and there are two empty cavities where the L & H adjustment needles would be. I contacted a Stihl rep and the only thing he said was maybe I allowed it to idle too much. So now I am shutting it off when not cutting. Now that it is out of warranty I plan to try other oils, such as Opti-2.
Boobala
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Way to go... just be sure to use a bit more than 1 (one) ounce (oz.) per GALLON of gas....... I use approx 1.2 oz. of OPTI-2 per gallon , if your problem persists I would remove the spark arrestor screen (unless you're cutting in a thick patch of woods ............
http://opti2-4.com/index.php?dispatch=categories.view&category_id=165
Keep us informed, it might still be another issue...... Boobala ....:thumbsup:
P.S. I just LOVE the B/S your rep told you about lettig it idle too long...... I have let my running equipment idle for more than 10-15 min at a time ....... ( moving branches / equipment etc. ) and never a problem ........
Boobala
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Got curious, I really despise any non-adjustable equipment. Anyway I found this ...... you MUST read the ENTIRE description ..........scroll down the page ..... this may be the cheap way out , a little modification to access the screws is all that seems necessary ....... as Trump says...... " whadda ya got to lose "...... :thumbsup:
............https://www.amazon.com/STIHL-MS170-MS180-Carburetor-Chainsaw/dp/B00CMOBTDE
............https://www.amazon.com/STIHL-MS170-MS180-Carburetor-Chainsaw/dp/B00CMOBTDE
That rep was probably an engineer and not a mechanic. I dealt with engineers for years where I worked.
I do want to check with the techs at the dealer where I bought the saw, just have not taken the time to do that yet.
Ok let me say this again , your carburator has High and Low Speed jets , they are hidden under the limitor caps otherwise know by mechanics as welch plugs .This was the model of Zama carb that Stihl used for a very short time back in 2011 . They are alluminium and must be drilled out carefully , then you would require a adjuster tool which is available via the dealer or online . Otherwise you could set the metering lever under the diaphragm a few thousands less to lean out the carb . Less complex solution invest $20.00 bucks on a fully adjustable Walbro Wt-215 carb online . The EPA guru, s do not want homeowners playing with these saws...duh ? Anyhow most Stihl that I tune regularly have a very lean setting requiring adjustment . As for your spark arrester screens get rid of them . Unless you cut within US Forestry areas lol . They will plug and cause overheating , stalling ..etc ! The MS 170 is a consumer , hobby saw not a professional grade unit , thus cheaper grade in many ways but a good saw for the average homeowner . I have ownered and still do 40 yr old Pioneers & new, Dolmar and Stihl and Husky Pro Saws. They are all getting more restrictive to maintain , between EPA Tuning and S**t Ethanol Fuel . I use nothing but Amsoil Sabre now rated for 50:1 to 100:1 oil Ratios , I never find carbon within my cylinder heads or spark plugs . However I will not bad mouth Opti 2 or Stihl Ultra when used properly . Anyhow if you can't figure the carb out just bring to a area small engine mechanic worth his reputation who will tune your carb properly , Hell with the Stihl Dealer Bullshit . If it was in my shop it would have been out the door within the hour ripping wood chips the size of nickles ! P.S. Nothing wrong with the Old Homelites of the 60's before Poulan bought them out lol .
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Hey , just got back from my Brotherinlaws , he was repairing a Stihl 017 (former MS 170) he installed a new Quankun carb fully adjustable from Amazon for $12.99 with 6 day delivery . So there you go no drilling or welch plug replacement and gluing required.
P.S. as for the location of welch plugs would be within the two holes you reported under the idle adjusting screw location . I would strongly suggest you remove the mesh exhaust screen once you replace the carb , you will notice significant power increase and fuel conservation . All the best , drop me a line if require tuning advice !
P.S. as for the location of welch plugs would be within the two holes you reported under the idle adjusting screw location . I would strongly suggest you remove the mesh exhaust screen once you replace the carb , you will notice significant power increase and fuel conservation . All the best , drop me a line if require tuning advice !