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AT fuel mix

Started by TrevorP, September 29, 2018, 10:33:44 PM

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TrevorP

This topic has probably been discussed exhaustively so I'll apologise now and prepare for incoming.
I've been using 50:1 in my 034 for many years - never a problem but it's not running day in/out.
I needed something for a bigger job and bought a new husky 565 - an AT saw.
The manufacturer recommends 50:1 but the dealer said he runs 25:1 - and not just for the first few tanks.
I know that manufacturers are constrained by EPA legislation and need to specify low oil content but does the dealer have a point, saying that 50:1 will cause hotter running?
Will it benefit from a heavier mix?
Will 25:1 lead to gumming up or carbon deposits in a saw that only gets occasional use?

HolmenTree

WelcomeTrevor!
Hey I want to hear how you like the new 70cc 565. Still no sign of them here yet.
Run 50:1
Making a living with a saw since age 16.

Southside

I don't have any AT saws by design and for what it's worth I run 32:1 in all of them. 372xt's, 395's. I even go so far as to use the Wally world marine 2 cycle oil that comes in gallon jugs. Never caused an issue for me. 
Franklin buncher and skidder
JD Processor
Woodmizer LT Super 70 and LT35 sawmill, KD250 kiln, BMS 250 sharpener and setter
Riehl Edger
Woodmaster 725 and 4000 planner and moulder
Enough cows to ensure there is no spare time.
White Oak Meadows

barbender

I like 32:1, I'm running that ratio in all of my saws including my Stihl 261cm. It runs just fine on it.
Too many irons in the fire

TrevorP

Only had it 2 days so it's a little early for a review but so far it's all positive - not too heavy and enough power for me (I've been using a 034AV for ~10yrs)

034AV - 5.3kg (11.7lb), 3.0kw (4bhp) @13000
565 - 6.5kg (14.3lb), 3.7kw (5bhp) @9300

Truth be told, the 034 suited me just fine but I sometimes came across a situation where a 20" would have been useful.
A few days ago the clutch on the old workhorse disassembled itself leaving me with nothing to perform surgery on a 30yrs dead, 20" Blackwood which had blown down on a friend's property.
I can rationalise a 'want' into a 'need' as well as the next man so I went looking.
I like to be in control of what the motor's doing and have been left helpless by microprocessors before so I wasn't keen on the M-Tronics and Autotunes being foisted upon us. The local Stihl agent had just sold his last MS391 - not getting any more, so I visited the Husqvarna agent, though I had a prejudice against the inboard sprockets of Huskys and reports canning the air filters. He had just taken delivery of the 565 which seemed to have answers to all of my niggles - better seal around the air filter, outboard sprocket, improved Autotune. He'd throw in an extra chain, extra oils, 5yr warranty, dropped $170 off the top. What could I do?
So the 565 has 5yrs to prove itself - if it stuffs up I'll be sure to let everyone know about it!

In the meantime I had this little issue about the mix to settle. If the agent's telling me albeit unofficially to use 25:1 he can hardly turn around and say "Your fault" if it carbons up.
I'm not too hard on saws - not harvesting giant Mountain Ash or even running a mill so I don't imagine I'm in danger of cooking it from using too thin a mix.

32:1 might be a good compromise.

lxskllr

I always used 32:1 in my poulan. Nice round number for mixing in my 1qt bottle. I bought some little bottles of Stihl ultra earlier in the year for my new Stihl and didn't consider the ramifications of that. It's setup for 50:1, so I mix it a little rich by leaving a finger of space under the marker on my 1g can.

I really don't think it matters. I've read tons of threads on chainsaw operation and maintenance this year, with people running mix ratios all over the charts, and haven't read anything that caught my attention one way or the other. Most fall between 32:1 and 50:1, so I'd run whatever in that range makes you feel better.

Regarding autotune... My new good saw is a 362cm. Works great, and it's a joy to use. Like you, I don't like having to depend on someone else to fix my stuff. On the other hand, I don't really like working on engines, and the electronics make it so I don't have to twiddle knobs to get it to run well. What *I'd* like to see is a usb port, and some software the user can use to at least troubleshoot their own gear. I can always dream, eh?  :^D

Good luck with your new saw! I'm sure you'll love it  :^)

teakwood

Run 50:1

I run all my Stihl Stuff with 50:1 (only org. Stihl Oil) since 20 years and i never had a problem. Even the 088 chainsaw milling here in the insupportable hot tropic climate did just great with 50:1   
National Stihl Timbersports Champion Costa Rica 2018

hamish

50:1 with good fuel and good oil.  Why would you want a leaner oil/fuel mix?
Norwood ML26, Jonsered 2152, Husqvarna 353, 346,555,372,576

Southside

More lubrication with 32:1
Franklin buncher and skidder
JD Processor
Woodmizer LT Super 70 and LT35 sawmill, KD250 kiln, BMS 250 sharpener and setter
Riehl Edger
Woodmaster 725 and 4000 planner and moulder
Enough cows to ensure there is no spare time.
White Oak Meadows

sawguy21

With modern oil I am not convinced, the extra just accumulates as carbon on the piston and muffler. I run my 2 strokes on 50:1 using Stihl oil, it is locally available, and have yet to see a problem
old age and treachery will always overcome youth and enthusiasm

Ed

All my 2 cycle ope get 50:1....oldest is an 020 Stihl from the mid 70's.

One has to remember, todays oils are vastly improved over the old 32:1 mix oil.

Ed

John Mc

20 years of running 45 or 50:1 in all my 2 cycle equipment - even older stuff that calls for 32:1, and not a single lube-related problem. (the 45:1 comes from mixing in a jug where it's hard to see the fill level, so I tend to err on the low side when filling with gas, targeting 0.9, rather than 1 gallon. I figure if I'm off, I'd rather be a little low on the fuel mix ratio than a little high.)

Surprising - a thread on oil mix ratios, and Al Smith has not chimed in yet. I guess he's just sitting back, munching his popcorn and enjoying the show.
If the only tool you have is a hammer, you tend to see every problem as a nail.   - Abraham Maslow

mike_belben

  Saws have fans to shed heat.  They cant do that so well if they arent running.  Whatever mix you run, let the saw idle here and there.  The fins can only absord so much heat before the piston to wall clearance starts getting tight.  And in that moment when things are tight, more oil is never a bad thing.  

I put 50:1 in my tophandle and leaf blower.. Tools that dont tend to get hammered on.  40:1 goes in the firewood saw, 25:1 in the concrete saw and the 395 when milling.  Carbon i can tolerate, a wiped out MAHLE jug i cannot.  I let the 395 idle after every pass, and pause to oil the bar sprocket.  On 50:1 the saw was clinking and tinking when i first tried milling.  Way hot.  Plastic was smoking one day when it ran out of fuel. 
Praise The Lord

Woodcutter_Mo

 The only AT saw I have is a 550xp, I just use the same fuel I use in all my other saws and trimmers. 50:1 with good fuel and good oil (Red armor, XP oil or Stihl Ultra is what I use). I occasionally mix a 2.5 gal mix (6.4oz) bottle with 2 gallons of gas if it's what I have on hand.
-WoodMizer LT25
-592XP full wrap, 372XP, 550XP, 455 Rancher, RedMax GZ3500T
-Fixer-uppers/projects:
024AV, MS260, MS361, MS460, Shindaiwa 488, 394XPG

DelawhereJoe

The 2.5 gal mix to 2 gal fuel is what I use, it was 32:1 for an old weedeater brand trimmer I had years ago but the fuel lines would junk out on me after 2-3 years on it. The Stihl equipment in the other hand never had a problem with the fuel bothering the lines.
WD-40, DUCT TAPE, 024, 026, 362c-m, 041, homelite xl, JD 2510

Andyshine77

I always recommend at least 40:1 and in your environment with all the dry dusty hardwoods, more oil is definitely a good idea. On top of that strato saws use less fuel which also means less oil, they run on the hot side too.  
Andre.

HolmenTree

Let the AT saws when hot idle for a minute before shutting them off.

I see the need for the next advancement in AutoTune and MTronic technology.... is a low fuel warning signal of some sorts.  ;)
Making a living with a saw since age 16.

barbender

I seems everyone is going to run what they're going to run...I like a little more oil, and I've had zero problems with carbon or plug fouling. I have had bearing failures when running 50:1. A grizzled old saw mechanic told me that bearing failures were unheard of in the richer mix days. So I run 40:1 and err on the rich side of that. If I was smoking out the woods, sticking rings and otherwise carboning up, I'd go to 50:1, but short of that I'll mix it rich.
Too many irons in the fire

HolmenTree

Yeah back in the good old "leaded gas days" the lead offered some protection by itself.
Once in the 1970's on a hot summer day I accidently straight gassed my 621 Jonsered. It stalled out quick but after it cooled off and after I got some fresh 40:1 fuel mix down the spark plug hole and into the tank the saw went on like nothing happened.

Pulled the muffler a few days later to check the P/C and was glad to see not even a scuff.
Old lead gas did its job alright but I sure wish I never breathed that stuff into my lungs for all those years.
Making a living with a saw since age 16.

pine

Quote from: HolmenTree on October 02, 2018, 09:10:32 AM
Let the AT saws when hot idle for a minute before shutting them off.

I see the need for the next advancement in AutoTune and MTronic technology.... is a low fuel warning signal of some sorts.  ;)
Got my first computer MTronic saw in July.  A Stihl 201T for climbing as the old one was worn out.  Did not want to go that way but no real choice anymore as that is all there is out there.
Your low fuel warning comment triggered a thought.
Why do you say that? Specifically.
I think I know...... but would like to hear it from you with your experience.

HolmenTree

Quote from: pine on October 02, 2018, 12:32:25 PM
Quote from: HolmenTree on October 02, 2018, 09:10:32 AM
Let the AT saws when hot idle for a minute before shutting them off.

I see the need for the next advancement in AutoTune and MTronic technology.... is a low fuel warning signal of some sorts.  ;)
Got my first computer MTronic saw in July.  A Stihl 201T for climbing as the old one was worn out.  Did not want to go that way but no real choice anymore as that is all there is out there.
Your low fuel warning comment triggered a thought.
Why do you say that? Specifically.
I think I know...... but would like to hear it from you with your experience.
Ok, we're on the same page about letting a working engine idle some before shutting it off. :)
Low fuel warning on a ATune or MTronic is a no brainer after running one of these saws hard in the wood and then it stops abruptly from running out of fuel. 
The high  heat sink soaks in while you're refuelling and then when you go to start it with the choke on to get the fuel back into the carb(I even tried no choke only fast idle) it dumps extra fuel into the cylinder for protection from the high heat it is sensing. Flooded and lots of cursing to get it going again.
Was a time you had  a little warning when the saw needed to be refueled. These micro processors adjust right to the last drop with nothing to spare to let them cool down at idle.
My MS261CM does offer a short lean warning but easy to miss, 562XP not so good.
Making a living with a saw since age 16.

pine

Quote from: HolmenTree on October 02, 2018, 01:24:51 PM
Quote from: pine on October 02, 2018, 12:32:25 PM
Got my first computer MTronic saw in July.  A Stihl 201T for climbing as the old one was worn out.  Did not want to go that way but no real choice anymore as that is all there is out there.
Your low fuel warning comment triggered a thought.
Why do you say that? Specifically.
I think I know...... but would like to hear it from you with your experience.
Ok, we're on the same page about letting a working engine idle some before shutting it off. :)
Low fuel warning on a ATune or MTronic is a no brainer after running one of these saws hard in the wood and then it stops abruptly from running out of fuel.
The high  heat sink soaks in while you're refuelling and then when you go to start it with the choke on to get the fuel back into the carb(I even tried no choke only fast idle) it dumps extra fuel into the cylinder for protection from the high heat it is sensing. Flooded and lots of cursing to get it going again.
Was a time you had  a little warning when the saw needed to be refueled. These micro processors adjust right to the last drop with nothing to spare to let them cool down at idle.
My MS261CM does offer a short lean warning but easy to miss, 562XP not so good.
Ok not where I thought you were going to go with that.  More below on my thoughts.
Absolutely agree about the cool down issue.  I have been very meticulous for years about letting my saws get a cool down after a hard run before shutting down.  You are right, my brush cutters (FS450/550) I can switch the choke to rich and get them to run a little bit longer for a cool down but the chain saws (at least mine) not so easy.  At least you can hear the RPM's increase as they start to run lean so you get a little warning that the tank is going dry.
The issue with the 201T is that of the five 201T that have been sold out of my local dealer in the last 3 months, 3 have had issues ranging from annoying to failure to run.  The technician replaced the carbs on two of them and the problem went away---- for a while.  Now one of those has returned and basically won't run at all.  Two of the 5 have had no issues at all reported by the users.  
Mine has been intermittent.  Initially it would die around 50% of the time on idle down after a WOT run. After break-in was complete and I started to run the saw much harder the issue was reduced to dieing maybe 10% of the time.
I know the computer "learns" as time goes on (according to the tech) and if different users use it inconsistently then the computer has problems with basically being confused.
After checking with one specific Stihl rep, Stihl claimed that it was a fuel solenoid issue and that the carb did not need to be replaced just  the tiny little solenoid.  That was done to mine.  The next hour the saw ran great no issue. Problem resolved  -- or so I thought.  
As the fuel started to run out I heard the RPM increase as it went lean (yes the computer should compensate but I could still hear it just like with my other saws)  I may have let it go a little too long but it did not die in the cut.  After refueling the saw ran great in the cut but went back to the previous issue with dieing at idle as the RPM decreased or if it sat and idled for more than a couple of seconds.
I was hoping that your comment was going to say that there was evidence that the computer got confused/screwed up if it was run out of fuel thus making it run bad due to computer issues.  Thus never to run it out of fuel to avoid fouling up the computer on these new saws.  Back to the drawing board on our issue.

HolmenTree

There's a  reason why these saws have transparent tanks to view the fuel level.
But easier said then done though when a guy is cutting in the thick of things.
Can't offer any advice on your MS201 besides there has to be a software update for it.
In my mechanical way of thinking a poor idle dropping off to dieing tells me the spark plug electrode gap is getting too wide.
Making a living with a saw since age 16.

realzed

Quote from: HolmenTree on October 02, 2018, 01:24:51 PM"Was a time you had  a little warning when the saw needed to be refueled. These micro processors adjust right to the last drop with nothing to spare to let them cool down at idle."
Boy can I relate to that! The first time I ran out with my new 261CM - I had no idea what happened.. it was like someone reached in under my arm and flipped off the kill switch it quit so abruptly.  No stumble - no lean elevated rpm that I noticed - no cough or fart.. just flat quit - 'BANG'..
I had been cutting firewood a lot longer than my 290 would ever have gone on a tank of fuel and I really should have taken note of that fact and figured the tank should be getting down considering how much I had done with it - but in the heat of things it passed me by.
It did start back up after a quick refill, certainly a lot better than I expected after hearing some stories of how hard the M-Tronic deals could be to get back after running out though, which was good!
It really is an amazing little saw - overall I am stlhl (pun intended) impressed every time I fire it up!  

HolmenTree

Yes knock on wood my new MS261 has been flawless too except once when it was working hard on a hot day in the upper '90s and ran out of fuel.
After refuelling I had to pull the rope about 5 times while holding the throttle wide open and it fired right up.

No big deal, I just thought it was saying to me "Take it easy! It's almost  100 F out here!"
:D

My 562XP wouldn't even have bothered to please me in that heat.
It wouldn't have bothered to run in the first place :D

:)  
Making a living with a saw since age 16.

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