What I was saying for the 2 saws I mentioned, that I was going to run what the spec said.
32:1 in the old Homelites and 50:1 in the Shindaiwas.
32:1 in the old Homelites and 50:1 in the Shindaiwas.
Not argumentative at all Mex , it,s the trade-off between lubricity and cooling epa. requirements .It all has to do with the molecules of oil being larger than that of fuel molecules though a fixed orifice (jet) in conjunction of fuel as a cooling agent and oil for lubrication . Most new premium syn oils have finer molecules that burn with the fuel charge (energy gain) and leave little residue or carbon fouling . Older thicker viscosity oils would give more horsepower gain from better ring sealing and higher compression , however could cause overheating (hot spots) issues from carbon fouling due to less technology and additives . The fact is that yes more oil means less fuel to air ratio , potential for a leaner running engine . P.S. As you are likely aware the dirty air filter would cause a rich fuel \ air ratio potential that Steve was trying to determineI don’t say this to be argumentative at all...but I have run into a couple of small two-strokes with fixed high-speed jets which seemed to run too rich on the top end. One was an old Homelite ST-200 trimmer (engine at the top, big fat curved shaft, single-line auto-feed head...and I think the same engine as one of the little red plastic saws. XL-2, maybe?) That was at my Midwest 725’ elevation in the summer. 32:1 helped a little, and a couple of additional holes drilled in the exhaust outlet finished the job. Ran great and cut really well for a couple summers...although my hearing range may now top out at about 12 kHz instead of 20kHz! LOUD trimmer.
The other is an old 18cc Weedeater Featherlite (square housing, not the newer jellybean-shaped housing) my Stepmom uses around her garden. She lives west of Denver CO at about 8,500-9,000 feet, and runs 50:1 in that and her saws (MS170, Husqvarna 50). When I visit I get weedeater detail. I mixed up a few quarts of fuel at different ratios last time as an experiment. It seemed to work about right on 20:1, a holdover from my dirt bike days as a kid. Smoked a
bit on that fuel, but ran pretty well considering the altitude.
I wonder how her MS170 does on 50:1 up there. I would ask but I don’t think she speaks rich/lean.
With the shindaiwas I agree . The Homelite that's a ancient oil ratio due to poor oil technology of the time , ensure to use quality oil to reduce carbon issues !What I was saying for the 2 saws I mentioned, that I was going to run what the spec said.
32:1 in the old Homelites and 50:1 in the Shindaiwas.
I agree majority of the 1st generation epa regulated Stihls were set quite lean from the factory ! I had to rejet a few 2010 , MS261 & MS361 .That must be an oddball 170. In my experience these are almost all borderline too lean but then I am only 250' above sea level. Can you post a photo of the silver engine family label on the handle so that we can know when it was manufactured? Also what elevation and temperatures are you cutting at? Both of these will affect the tuning.
yes in theory ! Try it out and get back to us !I run a little Homie XL with no high speed screw. Runs great on 40:1, but just a little rich. Would 32:1 lean it out then?
Very few of today s epa fixed jet saws run properly , that is why limiters are removed or welch plugs are drilled out to achieve proper tuning . To many variables , relative humidity , barometric pressure etc. I do not have any Electronic or Computerized saws . However have friends that do and many have had their saws reflashed due to erratic idle and high rpm miss,s . They have a way to go with their onboard micro processor controls . P.S. You understanding of current saw fuel & oil mix technology is correct !I'm starting to understand this a little more now. So with the better oils made today, less is needed to provide lubrication, but the equipment HAS to be set leaner. If you run a richer oil mix, then the equipment has to be set a little fatter. Correct? I've always just run 50:1 in my string trimmers and 40:1 in my saws, but the fixed jet saws never ran quite right.
40:1 in the Homelite with todays modern oil would be optimium , unless viscosity is paramount (engine wear issue) since it was recommended for 32:1 with old crude mineral oils . The Shinny in retrospect should remain @ manufacturer 50:1 unless you understand engine performance requirements . Just ensure you buy quality oil !My observation was that 40:1 in the Homelite was too rich so I suspected 40:1 would be too lean in the Shindaiwa.
That is the machine serial number. If the saw was registered by the selling dealer any dealer could look up the number and tell you when it was sold and to whom.I will look for the other label when I get back home later today. I don’t suppose the long number etched into the chassis below the muffler, visible in the one photo, can be decoded for any date info...?
The MS170 would probably have a very long life and not run very well on 50:1 at that elevation. This is one of the compromises of a fixed jet carb.The other is an old 18cc Weedeater Featherlite (square housing, not the newer jellybean-shaped housing) my Stepmom uses around her garden. She lives west of Denver CO at about 8,500-9,000 feet, and runs 50:1 in that and her saws (MS170, Husqvarna 50). When I visit I get weedeater detail. I mixed up a few quarts of fuel at different ratios last time as an experiment. It seemed to work about right on 20:1, a holdover from my dirt bike days as a kid. Smoked a
bit on that fuel, but ran pretty well considering the altitude.
I wonder how her MS170 does on 50:1 up there. I would ask but I don’t think she speaks rich/lean.
It is if the saw was designed to run on 50:1.Are you saying 40:1 is ill advised ?
Oils have gotten MUCH better in the years since the Homies were designed. They should be fine on 50:1 with high quality oil. However, they will need to be retuned for the richer (gas) mixture. This is where the issues come with the non-adjustable carbs. They can't be re-tuned if the mix ratio changes.What I was saying for the 2 saws I mentioned, that I was going to run what the spec said.
32:1 in the old Homelites and 50:1 in the Shindaiwas.
Correct.View attachment 827231Okay, here’s the label from the mysteriously running-rich-from-new Stihl MS170. If I am understanding that sticker, it was manufactured in May of 2018...?
I'll make a small batch and try it at least.Oils have gotten MUCH better in the years since the Homies were designed. They should be fine on 50:1 with high quality oil. However, they will need to be retuned for the richer (gas) mixture. This is where the issues come with the non-adjustable carbs. They can't be re-tuned if the mix ratio changes.
If you feel confident in your ability to identify lean running symptoms, that should work.I'll make a small batch and try it at least.
I think I am a bigger two-stroke nerd than you are.These oil threads crack me up. Pour some gas in the can, pour in amount of oil you want to use, finish filling can to desired amount. Shake, pour into saw and start cutting. It's your saw mix it how you want. It's my saw I will do the same.
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