Fuel

NevC

What fuel do you use for chainsaw mix?

I use standard unleaded (90) with 50:1 Husky Smokeless Oil.

Is there any advantage to using Premium(96?) or Ultimate (98) unleaded?

I think the unleaded fuel loses punch if not used. Have heard the higher octane unleaded can deteriorate in 30 days.

NevC

No edit, Use 25 to 1, not thinking clearly.

stihlman441

Stihl recommended minimum octane rating for the petrol for their saws is 89 AKI (R+M/2) this translates to Aussie RON rating of 93-94 so the usual regular 91-92 we get is Ozz is less than the recommended anyway.

So we should be using the premium 96 Ron Aussie fuels which is about 91 AKI.

This may help
Octane rating - Wikipedia, the free encyclopedia

NevC

Thanks for the response.
Is there any benefit or disadvantages with the additives in premium that clean the fuel system in cars?
I have made up a premium mix, and the 064 seems to start much better cold. Been too wet to try it out cutting as yet.

MrDiesel

My understanding was that the premium burned hotter and could cause premature wear on the saw

Rob Chace

25:1 ?????

huh?



well i use 40:1 (usually closer to 45:1) in my 50:1 machines .

MrDiesel

I changed depending on the saw

25:1 for 346, 575, 660, and 3120
50:1 for 338, 200T

Eric Frei

Fuel system cleaner is mainly for injectors.

I use normal unleaded but never ever that ethanol blend shit. Some guy on here warned that using premium unleaded can create combustion blowing past rings damaging piston and barrel. So I have gone back to the lower octane stuff.

I run 30ml Stihl 2 -stroke per Litre fuel, about 32:1

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gooddog

I'm with Eric on this one. I would use lower octane non ethanol before ethanol high octane. With that said, high octane fuel will stay usable for a longer time just so it doesn't have ethanol in it. The fuel stations near the snowmobile trail here sell pure gas premium, but some of the snowmobilers here still get on a ethanol/water treadmill. They run ethanol fuel which absorbs moisture into the fuel tank. They start having moisture problems so they add HEET into their fuel, which then will draw more moisture into their fuel.

I premix at 40:1 and adjust my carbs slightly richer for fuel when needed. When a person mods a muffler, the engine breathes better so I find it needs slightly more fuel. If you change your pre-mix ratio, it slightly changes your fuel-air ratio. If your putting more oil through your main jet, the less gasoline is going through it. We used to do race day rejetting by changing pre-mix ratios on moto-cross bikes, snowmobiles, karts, and jet skiies. All of those being premix models. If you take a new saw made to run on 50:1 and switch to 25:1, you might notice it seems lean on fuel. The older saws, this is not as noticeable as the new clean running saws.

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gooddog

Another problem with ethanol fuel is when it absorbs enough moisture, it starts forcing the oil out of the pre-mix. We tested this theory in the shop back in the 80s. We ran 10% gasohol premixed at 32:1 with golden spectro 2-stroke oil. In a glass jar, we slowly add water to the mix. You will notice the water gets absorbed in the alcohol instead of sitting on the bottom. After a while, the mix gets cloudy and the oil turnes into small droplets.

That is why I hate to use any alcohol in a premix. At least it is easy for saw people to shake the saw before you run it if it has sat for a while. And, always shake your cans before filling your saws.

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superfire

Me I buy mid grade gas from a good service station and run premium brand name two stroke mix. Never had much issues since I fattend up the saw a wee bit. Clean fuel is the most important thing in two stroke engines. Some service station have weird sediment in there tanks .

NevC

The Stihl book states 50:1 with Stihl oil, and 25:1 with other brands.
Husky is also 50:1 with their oil and 33:1 otherwise.
I used neither brand of oil for a while, just what was available locally, so got into habit of 25:1.
Could you assume Husky/Stihl oil would be compatible and go 40:1/ 45:1, or just 50:1 as books state?

I spoke to a wood cutter yesterday at servo. He uses 95 and 30:1 oil in some saws as he says they run better, the extra oil is to keep piston rings wet (his words).

Interesting subject indeed.

Nev

treerat

This is all I have been using for the past 15 yrs+/- Midgrade (90) and husky XP oil Never a problem. still running the 51 that I bought in 97' never a problem with it. I have had excellant luck with no issues ever. hey whatever works stick with it....Be safe

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Logger Ally

Here in the PNW I use Clear at least that's what it says on the pump. It's a standard 96-98 octane rated Non Ethel pump fuel and is always fresh. I use premium synthetic 40:1 on my big cc saws and put new plugs in every season on all the runners and never had a issue at factory spec's on a saw.. Funny how many stories of old timers wanting to know if they can use 2 stroke boat motor oil in a saw Please Don't!! as I always offer to give them some..I've heard of some good ones though

superfire

The new fuel is hard on spark plugs. I carry a couple extras to prevent down time.

Brent Ferris

I use premium fuel (here mid and low octanes have ethanol added) and run both Stihl and Husky with 40:1 - saws run better, last longer, new spark plugs are cheaper than engine repairs because of lean mix.

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nmurph

10% ethanol blends run fine. they can cause problems with the rubber and it can absorb moisture. but the mix fresh will eliminate that problem. i put the lid on the can as soon as i finish refilling. i haven't had any problems with 2mon old mix.

premium is neither less or more stable unless it has additional stabilizer added.

premium does not burn hotter--additives cause it to be slightly more resistant to to ignite, but it does not change the energy released.

you can get into problems with incomplete ignition if the octane is too high.

you don't get increased performance with higher octanes above the point at which all of the fuel is igniting as the engine was designed. you are simply sending unburned fuel out of the exhaust.

running lower octane fuel can cause pre-detonation which will cause cratering of the piston if it is done for extended periods. pre-detonation is worse when a saw is running hard or under partial load (those of you old enough to remember bf FI and computer management can remember the rattle as you eased onto the throttle or started up a hill.) a 2pt decrease probably isn't going to have much effect.


50:1 premium synthetic oil mix with 89-92 octane is adequate for any CS; old or new. if you are milling, where prolonged full throttle cuts are the norm, a 32/40:1 ratio might be justifiable.

if you have lowered the squish or ported your saw, you need premium. otherwise, mid-grade will work just fine.

APSE

I'm not much on the math that involves higher octane fuels. But, basically, if you are not running an engine higher than 9:1 compression ratio, it is not only a waste of money to use the higher octane fuels, but it also causes the piston and cylinder to carbon up MUCH FASTER than if you used a regular grade fuel, because there is not enough pressure to burn it effeciently, therefore leaving behind unburnt fuel mix residue with every stroke. And yes we have found that ethanol blended fuels are harder on the carbureator parts as well as the fuel lines, especially if they are stored with anything left in them. If the manufacturer recommends 50:1 mix ratio, then up to 40:1 is okay, a little more oil only fouls the spark plug quicker and a little more carbon build up, but it is cheaper than damaging a piston and cylinder. If you go to 25:1 you're gonna have a smokey mess and a badly carbon'd up piston and plug up the spark screen quickly also (not to mention sticking rings).

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NevC

This is really god info and has cleared a lot up for me.
One reason I had for asking, is my 064 hates anything but fresh fuel, yet my other saws will run on what I empty out from it without problems.
It's also hard at times to pick when to take choke off, if you miss its a b???? to start.
Could this be from too much oil?
Thanks all for help

stihlman441

For us Ozzys Premium 96 (ron) is the go,remember we add oil,as it gets older,every time you open container and it goes sshusss,all these thing lower the octane, ron amount.

As i posted before recommend min for Stihl saws is 89 (AKI) U.S

89 (AKI) = Aussie 93-94 (Ron)

gooddog

I have read that when you add 2-stroke oil to your fuel, it lowers the effective octane rating of the fuel. Then, that makes sense why you start with a higher octane fuel.

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I'll be fine if my body holds out.

nmurph

no, oil is pretty much non-combusted in the cylinder. extra oil in the mix does make a saw run leaner. if a saw is tuned for 50:1 and is switched to 25:1, the saw needs to be tuned.

gooddog

Quote from article: First, when fuel is premixed with 2-stroke oil, the octane rating is reduced by about 2 points. An 87 octane fuel would therefore become 85 octane.

article: Feeding your Rotax 2-stroke Aircraft Engine | Rotax fuel, Rotax octane, Rotax oil, 2-stroke oil

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superfire

There is another spendy option out there. It is call premixed fuel. It comes in 40-1 and 50-1. Stihl even has there own rebadged cans. The stuff unopened lasts up to 5 years in the right conditons.

NevC

Another side to this FYI.
I asked the Husky dealer I frequent what is his recommendation.

He said we have some sources of suspect petrol around the area that have caused hard starting and/or damage to barrel when used.

To overcome this, he says to use quality 50:1 oil, mixed to 25:1. This will give you a safety margin for any potential damage. Won't help the poor starts though of course.

I did have some fuel from a country store a while ago that would not work at all in the 064 or 029, so it went in the tractor.

sharkey

I see alot of cylinders from the inside. Most of the carbon you see in a cylinder comes from the burned fuel not the oil. Oil is designed to float carbon. Consider that new bio oil that is made from Beef Tallow. It wont start to burn until it hits 650f. Exhaust gas temps will hit 750f in a chainsaw muffler under load but not in the cylinder. Any performance two stroke engine will benefit from higher octane pump gas.

Rob Chace

and thats about it really.

rogue60

there is one thing to watch out for its 2 stroke with no dye in it, you cant tell if you have mixed your fuel.i know a bloke that seized a 066 with a few hrs on it! thought he mixed hes fuel but hadn't! stay away from that crap!