octane in a sthil

samT

New Member
The quality of the gas out of the station has been very poor latley /forum/images/graemlins/crazy.gif
I have a friend who is reitred from the fire-department and a big time airport bum.
He said the fire saws had problems all the time, 'till he put them all on av-gas (100 octane low lead ashless dispersment gas). Do you think that's a little too hot for the sthil's? I'm running 2 MS200T's 1 Ms170, and an old 066.
 

R_Schra

New Member
In the netherlands we have the stihl mix and aspen fuel...but not at our company:(

I run my stihls on 98octane unleaded. Had no overheated or broken saw in 8 years now. (broke a 020 some years back, fell out a tree) Other employees use 95octane unleaded and they have had this winter 4 broken saws.... (088, 2x 036, 066) I think on 95octane with dirty airfilter the engine will run to lean and heat up. also with lean mixture less lubrication from the mixed oil. so that cost them some new pistons and cilinders.
 

Mange

New Member
What you boy's refer to is Alkylate fuels. This is not (too my knollege) availeble in the USA.

In Europe/Scandinavia this is the only right thing. This is no BS.
How ever it is now way to get this in USA.
The Aviation fuel is a Petrol product.
If you are interested I can show some facts.
 

Merak

New Member
Are you certain the saw is tuned properly? The only thing the octane does is keep the saw from knocking. If the saw runs lean on higher octane, it was too lean on the lower octane. Low lead avgas has a lot of lead in it, enough that it will foul the plug if you don't change it regularly.
 

samT

New Member
We change our filters and plugs once a month minimum. tuned properly regularly.
I'm thinking it might have to do with all the ethinol in the gas here. Why would the lead foul the plugs in the saws, but not the planes? 'cause they are 2 cycle?
 

Merak

New Member
The gas does foul the plugs on airplanes. Thats one of the regular jobs when servicing the plugs is picking the chunks of lead off the electrodes and insulator. You don't throw away aircraft plugs unless they are bad. When I worked on small aircraft years ago they were $10-15 each, and there are 2 per cylinder. Your problem may be as you said, the ethanol. See if you can find a station that sells sraight gas.
 

Mange

New Member
I think this is two seperate problems that interact.
Do you know heat there is, prehaps a different plug could help, as this clearly is a heat thing. If you have a special fuel perhaps a special plug could help a special saw?! /forum/images/graemlins/ahhhhh.gif

Mange.
 

samT

New Member
Well I've asked at all the stations in town. Looks like I'm out of luck on the straight gas, it's all ethanol around here 10% and up. /forum/images/graemlins/frown.gif
 
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