higher octane.

[Aaron]

does anyone run there saws on the higher octane petrol you can buy and is there any noticable differance or is it any better for the saw. sorry if this has been covered before.

 

Aaron

[arbwork]

I use tesco 99 or shell in the rally car any left over we use in saws etc. rather than store it , I notice no difference except in price!

[sloth]

Was told by a still dealer and expert not to use it in 200t's, as they are finely tuned for 95 octave, and the hotter burning of 99 can increase chance of crankcase seal problems. Not sure if it is true though

[Xerxses]

Was told by a still dealer and expert not to use it in 200t's, as they are finely tuned for 95 octave, and the hotter burning of 99 can increase chance of crankcase seal problems. Not sure if it is true though

 

The local dealer has made some tachometer trials with Aspen+ (higher octane) and swears by it! I have tried it but have to admit that an extra sharpening makes more of a difference! Mind you, with a new chain you can tell the difference!

[AndrewS]

I've wondered the same thing myself but can't really see how it would make any useful difference. Fine in a high-performance 4-stroke with knock sensor and variable ignition timing, but chuff all benefit in a simple 2-stroke because there's no way (that I'm aware of) to advance ignition timing to increase cylinder pressure (& hence efficiency/power).

 

Having just come back from a break in the US, interesting to note that they can only buy 87, 89 or 91 octane at the pump - yet Sthil claim similar power output across the product range (vs UK).

 

My conclusion; keep the chain sharp, the air filter clean and use fresh 95RON fuel from a reputable supplier.

[Megatron]

I don't think you would notice any difference in power. It is just that you may need the higher octane in a race saw due to the higher compression of the engine, to prevent detonation.

 

in a simple 2-stroke because there's no way (that I'm aware of) to advance ignition timing to increase cylinder pressure (& hence efficiency/power).

 

My conclusion; keep the chain sharp, the air filter clean and use fresh 95RON fuel from a reputable supplier.

 

You can advance timing by either removing or shaving off some of the woodruff key. The key is only used to ensure the flywheel is in the "right" place, it is the crankshaft taper that prevents the flywheel from spinning on the crank. ...or just buy a saw with points and condenser.

 

Agree with your conclusion

[Maico490]

I use tesco 99 or shell in the rally car any left over we use in saws etc. rather than store it , I notice no difference except in price!

 

 

Some of these premium fuels have ethanol in them to help raise the octane rating. They are therefore more likely to absorb water if not used quickly enough. This isn't usually a problem in cars but for 2-strokes it can equal an early death. Just take a look at the US chainsaw sites to see how many problems they have with ethanol and you will see that it is a blessing that the Government went off making it's inclusion in all our petrol compulsory due to rising cereal prices.

Just use fresh ordinary unleaded with good oil and don't mix more than you will use in a few weeks.

[easy-lift guy]

I run 90 Octane with no ethanol. Any thing higher could damage the pistons or so I have been told by my dealer. The key is No Ethanol.

easy-lift guy

[Aspen@AAOIL]

Just to clear things up regarding all of this,

 

The octane rating on fuel is its ability to withstand detonation.

 

In the UK we show The RON value at our pumps (Research Octane number)

 

In the US they show the AKI value (Anti Knock Index) which is an Average of RON and MON (Motor octane number). this is why you may get confused as to think the octane is lower on american pump fuels.

 

For example, 95 unleaded in the uk has a typical octane of 95 RON and 87 MON. AKI around 91.

 

Octane is not especially important for a chainsaw, the most important thing is that you get your fuel from a good source. i would strongly advise not using supermarket fuels unless you really have to as these are known to be the worst.

 

Regarding Ethanol:

 

Ethanol is an oxygenator which increases power and lowers emissions, all fuel in the UK at the pump is currently E5 (5% ethanol) but is set to rise to 10% in the near future.

 

in the US, in most states it is already a requirement that all pump fuels should be E10 and this is what is causing problems for garden equipment in america.

 

The problem with ethanol is that it attracts moisture if not stored carefully and this is not good for engines. Ethanol is also very corrosive and E10 in america has proven that the rubbers in carburettors in particular do not like this high level of ethanol.

 

In short, fuel is set to get worse for your chainsaws if your buying from the pumps for your machines.

 

The solution to all of your fuel worries:

 

Use Alkylate petrol (such as Aspen) which contains no nasty ingredients which could damage both you and your machines!

 

[hardtop110]

I would strongly advise not using supermarket fuels unless you really have to as these are known to be the worst.

 

Really?

Do you have a reference for that?

 

I was of the opinion that supermarket petrol stations shift more fuel than some others and so it tends to be fresher. Is that assumption wrong?