How critical is fuel/oil mix in these things? Can a (whatever) 40:1 instead of the Stihl recommended 50:1 kill a saw? I keep getting these things (Stihl anything) back with scored pistons and rings (I work for a rental company). Everything goes out with a full tank of pre-mix. We offer to give them a 5L of pre-mix. When they take it (weekend warriors) I never have a problem when the tool comes back. Only when they say "I have my own gas and oil mix." do I get stuff back not working. Scored pistons and cylinders.
Stihl 2-cycle mix question.
- Thread starter Keith Lee
- Start date
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Why not just make it a condition of renting the saw that they MUST use your fuel?
Seems like that would be cheaper than rebuilding saws a bunch.
I've experimented with everything from 60:1 to 32:1 in my 261 and 462....no scored pistons. So...I don't believe that should be an issue...
Seems like that would be cheaper than rebuilding saws a bunch.
I've experimented with everything from 60:1 to 32:1 in my 261 and 462....no scored pistons. So...I don't believe that should be an issue...
If it's an oil problem it's likely either no oil at all, or really low quality oil. Saws can seize due to misuse too. Dull the chain by hitting dirt and then keep cutting by dogging the saw.
40:1 would be fine, maybe needing a slight carb retune if they're not Mtronic, but it won't keep the "I have my own fuel" crowd from straight gassing it or using 30wt like they did in the '70s. Or the uses a saw like a ditch witch crowd from running a dull chain.
I hope the dolts who seize rental saws get charged for it!
40:1 would be fine, maybe needing a slight carb retune if they're not Mtronic, but it won't keep the "I have my own fuel" crowd from straight gassing it or using 30wt like they did in the '70s. Or the uses a saw like a ditch witch crowd from running a dull chain.
I hope the dolts who seize rental saws get charged for it!
WI_Hedgehog
You bought a WHAT???!!
A 40:1 ratio using STIHL oil is not good in a 50:1 powerhead. Running STIHL oil rich carbons up the spark screen and combustion chamber. The Engineers at STIHL formulated the oil to run well at 50:1, full-throttle, with fresh high-octane ethanol-free fuel.
Fuel containing ethanol goes "stale" in 3 months, quicker in hot temperatures. What happens (from what I understand) is the fuel loses the more volatile components and burns leaner, which means hotter. Comparatively, a vehicle has O2 sensors and adjusts the fuel/air mixture, a lawnmower has larger cooling fins and more mass, and both are 4-stroke oil-cooled (the vehicle has liquid cooling also). A handheld 2-stroke "race engine" in a string trimmer or chainsaw running lean quickly runs too hot and the oil breaks down leading to what you're experiencing.
I'd rather need to remove carbon than scoring
I don't know that I've ever rented anything 2 stroke without them requiring I use their mix.
Sounds to me like the old straight gassed issue.
WI_Hedgehog
You bought a WHAT???!!
Mix the correct ratio with fresh gas and you won't have either issue. Some people like 40:1 or 32:1 (ported saw guys), use AMSoil for those ratios.
It could be, but not necessarily; someone could have leftover gas from last time they used a saw six years ago. (It's a rental, who cares!!!)
With that said, I take care of the stuff I rent like it was my own "brand new" equipment, and for some unknown reason the rental place gives me a hefty discount. I don't ask for a discount, I just respect their business with which they make a living and take care of their family.
I would imagine that I too will be getting into saw issues as well, in as much as my Kubota dealer who I work for part time has just taken on an Echo franchise and I get to be the 'elected' repair person. Hopefully, his customers have some common sense but I doubt it. People today seem to be woefully ignorant. One thing I NEVER do is loan my saws or my truck or anything else for that matter to anyone and that includes my son.
TN Cattleman
ArboristSite Member
I would hate to be the one renting chainsaws out to weekend warriors. If you send pre-mix with them, some are still likely to use their mix and keep yours.
Its true that modern fuel goes stale, but I respectfully disagree with the rest having used 40:1 for years. Yes running two strokes with more oil can necessitate more maintenance and cleaning, but this doesn't cause damage like running them with too little oil. 40:1 just gives you more margin for error. Its important to tune regularly for the mix you are using
Removing the spark screen is the first thing I do when I work on a new saw (wet climate) so that's not a problem but even if you have them they are really easy to clean with heat. I clean spark plugs with fine sandpaper. Yes I've seen carbon in the combustion chamber and I have tried to blow it out but I don't think its ever been a problem.
Assuming theirs is mix.
42:1 is what I always use, mix non-ethanol gas with good grade chainsaw 2 stroke oil.
Timber MacFallen
ArboristSite Operative
Honestly, any decent quality oil mixed in a reasonably close ratio isn't going to result in a torn up saw. There are other reasons you probably see problems:
1) People starting a cold saw and then proceeding to go into a full speed cut before it's come up to temperature. I'd instruct people to let the saw warm up a couple of minutes and blip the throttle 20 times before before starting.
2) People running a dull chain at full throttle and not providing enough load on the engine. This is hard on a saw.
3) Running the saw at non stop full throttle even when you're just handling small branches and limbs.
If I rented saws I would send them out with a one gallon can of 40:1 mix using Echo Red Armor or Amsoil Saber and a gallon of Echo bar oil (good and cheap). They are red and blue respectively. Tell them if they use any fuel or oil but yours they can lose their deposit and are responsible for repairs. Build fuel into the price. Check the fuel upon return by pouring some out.
Even an idiot will have a fairly hard time ruining a saw with that plan in place. Saws should last hundreds of hours and provide years of service if maintained (pro saws anyway).
A nice addition on what is now expensive chain saws would be positive lube oil injection like some dirt bikes used to have. That way there would be no lack of lube oil and the oil tank should last a while anyway. Positive oil injection isn't complex (just like a bar oiler, mechanically actuated) but unlike a bar oiler, would have a base idle bypass so when not turning, but idling, a small amount of oil would be fed into the cylinder, all the time. Sure would save a ton of grief IMO.
The first thing most dirt bikers and jet skiers did was remove the oil injection system because of the high failure rate.
Not at all cognizant of that myself. Last 'dirt bike I owned was a Yamaha 250 dual sport and it was just fine. Ran Klotz injection oil in that. All my 4 bikes are now 4 strokes now.
Timber MacFallen
ArboristSite Operative
Why cut into parts or new saw sales? Consumer mistakes keep the gravy train rolling
Yeah, if you saw the little plastic gears that run those oilers, and how tiny the hoses were, that's all that was keeping you from straight gassing your ride...
