spacemule
The Peanut Gallery
The saw gets upset if you don't put a little bar oil in it and warm it up before sticking it to the wood. Can you blame it?
who warms up their saws?
- Thread starter wood4heat
- Start date
Help Support Arborist Forum:
Jonsered2095
ArboristSite Guru
Hmmmmm.....I read a study where 90% of the wear on an air cooled two stroke comes in the first 5 minutes. How could that be? Maybe the piston is expanding up to proper running tolerance and not slapping anymore? That is the piston cyl is enginereered to give the PROPER tolerance at running temp (e.g. HOT)
What if it is still slapping when you bury the bar into that piece of dry locoust or hickory.....SLAP SLAP SLAP........the rings are cocked off a bit too as they slide by the ports.......
Off topic here, but I've built many two stroke bikes. Nobody here seems to give a damm about piston/cyl clearance or ring end gap, even with modded saws.
With bikes I've seen things way off from the factory. Hell, a 4 cyl 4 stroker came in WITHOUT a piston/rod assy. We were trying to figure out why a new bike vibrated so much and had 0 compression on 1 cyl.......
Tolerance is another way to determine how "bad" a piston is on rebuild. It is not only scoring but sloppiness/taper. Same with a cyl but less so as they (chrome/nikasil) don't wear as much. Both should be checked at several places to determine wear/out of round.
Any service guys have typical specs for this? Maybe Andy could provide some wisdom?
Which goes into another thought. What "hotrodders" would call "blueprinting" an engine. That is assembly BETTER than the factory does with increased attention to tolerances and fitting. We used to call it horsepower for free (time excluded...)........
What if it is still slapping when you bury the bar into that piece of dry locoust or hickory.....SLAP SLAP SLAP........the rings are cocked off a bit too as they slide by the ports.......
Off topic here, but I've built many two stroke bikes. Nobody here seems to give a damm about piston/cyl clearance or ring end gap, even with modded saws.
With bikes I've seen things way off from the factory. Hell, a 4 cyl 4 stroker came in WITHOUT a piston/rod assy. We were trying to figure out why a new bike vibrated so much and had 0 compression on 1 cyl.......
Tolerance is another way to determine how "bad" a piston is on rebuild. It is not only scoring but sloppiness/taper. Same with a cyl but less so as they (chrome/nikasil) don't wear as much. Both should be checked at several places to determine wear/out of round.
Any service guys have typical specs for this? Maybe Andy could provide some wisdom?
Which goes into another thought. What "hotrodders" would call "blueprinting" an engine. That is assembly BETTER than the factory does with increased attention to tolerances and fitting. We used to call it horsepower for free (time excluded...)........
Austin1
Addicted to ArboristSite
Nice post! Thats why you build a motor different to run on forged pistons than cast.
Jonsered2095
ArboristSite Guru
Uhhhh...I don't know...Maybe
But what do studies know... someone must oppose this view :taped:Uhhhh...I don't know...Maybe
Long time ago and I don't have a link, might be before internet? From what I remember Huqusvarna did the study might have been saw or dirt bikes, think there is much difference?, maybe Stihl is immune???
Anyway a gentleman seems to understand in an above post concerning car pistions, I won't go into Ford vs Chevy............forged pistions expand more so require both more clearnce and warm up time................if you don't do it they "slap" the bores..........if you rev/abuse the motor before warming up you can/will damage the pistion skirts.............if you do not have the proper clearance upon warm up it will be too "tight" (siezure) or will flop in the bore.....As I remember the diferenece between the two was 2-4 0.001 inches..............which brings us back to saws? And the question I wonder about with no service manual................
Last edited:
Jonsered2095
ArboristSite Guru
I was being sarcastic...
And yeah, lots will agree that Stihl is immune. You don't have to be here long to realise this.
Of course metals expand and contract, and therefore tolerances also. Nothing is absolute.
So how do you warm up your saw? This is the topic of this thread after all.
blis
Addicted to ArboristSite
I never warm up the saw on purpose, but i tend to start it near the woods/cutting site and let it idle that minute or two while i walk towards first tree to be felled... I find it warms enough in that, but cold saw should never be reved like no-tomorrow....
Sprig
Addicted to ArboristSite
Pretty much where I'm at with the topic, if I know the first cut is going to be a sustained one I might warm it up a bit more or take it easier (ie. not WOT) for the first few minutes. When it does get really cold here I expect to be somewhere close to the fire, not out cutting
Wasn't this topic covered a couple of times before? :monkey: :deadhorse: 
oldsaw
"Been There, Milled That"
I'm kind of the same. The only difference is the 3120 for milling. That gets a minute or so before I open it up. The other saws cut as soon as they are "cleared" and not stumbling.
Mark
rreidnauer
ArboristSite Operative
Refer back to post 18 and to 43. Piston expansion excessively exceeding the cylinder under heavy load can result in excessive wear, scoring, or even seizure.What is the point?
These engines lubricate better at higher RPM's than idle.
Once the piston has warmed up, it is time to run it.
I think this "warming up" idea is a cross over from the fine days of pre-FI trucks and cars that people would idle forever cause they thought they were doing it "good". In fact, it wasn't that great.... Even the newer stuff will do better if driven modestly until warm.
However, I don't crank the saw up, and 9 seconds lay it into a 22 inch cut. I might cut a few limbs at less then full power, then go for it!
-Pat
I know what your saying about better lubrication at higher RPMs, but I've never seen a saw that ended up with a scored P&C at idle. I don't think big block V8s (operated at maybe 30% power on average) and high power to weight ratio, ultra compact two stroke engines (normally operated at 100% power) fall into the same category. I will agree that once at operating temp, better lubrication occurs at higher RPMs.
Austin1
Addicted to ArboristSite
I agree I think that's what we all do. But then some of the posters here have never cut in real cold weather.I normally walk about 30 metres to my tree from the truck. But in real cold weather that is at half choke.
P.S Right now I have frost on the ground!
Last edited:
I cut in weather that ranges from the 90s (this week) to freeeeeezzzzing (-20F). The saw will always run a little funky until it's "happy" drinking the mix. At this point I can rev it without it blurbing and could start a cut. Instead I wait until the cylinder is hot to the touch, this tells me everything inside has expanded up to the point that the internals are not going to slap each other. It also gives the oil pump some time to fill the groove in the bar for the first cut. I am more meticulous about this with my bigger saws (which cost more too) that I use for milling.
I'll start another thread concerning piston cyl clearances...........
I'll start another thread concerning piston cyl clearances...........
blis
Addicted to ArboristSite
well it gets around -35c here in winter so i ought to know how to cut in cold weather :notrolls2:
However, EVERY engine needs to be warmed up atleast a bit, especially 2-strokers... The colder the weather longer it takes and more important it is (due to bigger differences in temp)...
warmup
i warm up everything just a bit. new cars warm up when you drive gently at first. old car gets about one minute or two, then gentle driving. water cooled two stroke warms up while 1 or 2 min (while fixing the helmet, gloves and such) then finish warm up by riding easy. air cooled stuff like chainsaw gets a minute or two idling, or some idle and then some low revs to oil the chain. lawn mower has more mass, at least one full minute of idle (new lawnmowers dont even have throttle, do they?).
everything cools down at idle before stopping, too (except not turbocharged cars and trucks get turned off when done). I never make heavy cuts with the saw when the tank is low because I don't want it to stop lean (out of gas) under high load/high temp conditions. If it starts acting like out of gas, I hold upright and try to get the last of the fuel in the tank to keep idling so that it is cooling down as I walk to the fuel area. if it happens to die under big load because I wasn't watching the fuel, then I might choke and try to run it by modulating the choke to get some air flow as I walk back to fuel.
bad news is, my stuff lasts forever and I never get new gear because I am not abusive enough.
i warm up everything just a bit. new cars warm up when you drive gently at first. old car gets about one minute or two, then gentle driving. water cooled two stroke warms up while 1 or 2 min (while fixing the helmet, gloves and such) then finish warm up by riding easy. air cooled stuff like chainsaw gets a minute or two idling, or some idle and then some low revs to oil the chain. lawn mower has more mass, at least one full minute of idle (new lawnmowers dont even have throttle, do they?).
everything cools down at idle before stopping, too (except not turbocharged cars and trucks get turned off when done). I never make heavy cuts with the saw when the tank is low because I don't want it to stop lean (out of gas) under high load/high temp conditions. If it starts acting like out of gas, I hold upright and try to get the last of the fuel in the tank to keep idling so that it is cooling down as I walk to the fuel area. if it happens to die under big load because I wasn't watching the fuel, then I might choke and try to run it by modulating the choke to get some air flow as I walk back to fuel.
bad news is, my stuff lasts forever and I never get new gear because I am not abusive enough.
motosierra
ArboristSite Guru
-35C = -31F so not too big a difference (-31 there vs -20F here). What you like to run for winter bar oil? I like milling in the winter as saw and bar are happy in a fat cut, if I'm cold I'm not working hard enough.
blis
Addicted to ArboristSite
I run regular oil all year and it seems to work fine atleast in -15c, but my uncle claims that when it gets below -25c you have to dilute it a bit with diesel...
Austin1
Addicted to ArboristSite
My post wasn't aimed at you.
I know how cold it gets in Norway
SawTroll
Information Collector
Latest posts
-
-
-
-
-
Petzl Pantin foot ascender vs Notch Jet step foot ascender- Latest: Hatchville Homesteader
