Piston on chainsaw

Tomjim

I have a stihl chainsaw 18 years and done very little work with it, used a few times a year.

The piston is whacked and the garage thinks it is down to the fuel

I always put oil in the petrol and kept petrol in a jerry can

In some cases the petrol mix may have been in the can for a few months

Any views as to what the issue is?

I'm getting it fixed so don't want it to happen again

patsy_mccabe

The lubrication for the engine is the oil you add to the petrol. If this is not added to the petrol or is of poor quality, it will lead to scoring of the cylinder. I always shake the mixture too before adding.
Another thing to consider is how you start the saw. Once started, you should allow it to just tick over for a minute or so , to allow the cylinder to heat up. saw a video on this before. I'll try and find it on youtube.

patsy_mccabe

Here;

feartuath

Two stroke oil is heavier than petrol and will drop to the bottom of a can if left sitting for a few weeks.
Always shake a can before filling any 2stroke engine.

LastFridayNight

Two stroke engines are fickle beasts when it comes to fuel mix. Too much oil, too little, wrong oil type, pump petrol that’s been sitting a few months.. all will cause issues sooner or later. If you’re only using the saw a couple times a year, it might be worth buying Aspen 2 stroke or Sthil motomix for it. Takes all the guesswork out for mixes, and a can of it can sit in your shed for years and not go off. Aspen fuel is 3 or 4 times more expensive than regular unleaded, but for occasional use, will pay for itself through reducing maintenance and engine rebuild costs.

Thepillowman

Only mix a gallon at a time here using saws over 30years only ever used husqvarna 2 stroke, never burnt out a engine yet. Make sure they do a pressure and vacuum test on it. An air leak will burn out a piston in minutes.

Fine Day

Not sure if I was been told a yarn but I was advised never to store a saw on a concrete floor as the chemical makeup of concrete will eat the bottom of the saw over a long time particularly when damp. After that I always sit the saw on a piece of timber.

Turbohymac

Hi op.. I always use a known brand of 2stroke oil and I always go a bit more oil into the petrol than is recommended..its irrelevant if the Jerry can is then left over the winter once you shake it up well before using it again.. if the petrol is gone flat the chainsaw simply won't start but there's still plenty lubrication.
However you also need to keep the air filter clean any tiny bits of crap getting in through air intake will also score the cylinder..

patsy_mccabe

I dunno about using more 2 stroke than is recommended. If it was better for the Saw, then the manufactures would recommend more.

bogman_bass

+1 on the aspen.
The extra cost is small compared to a saw not starting when you need it

minerleague

Turbohymac wrote: »

Hi op.. I always use a known brand of 2stroke oil and I always go a bit more oil into the petrol than is recommended..its irrelevant if the Jerry can is then left over the winter once you shake it up well before using it again.. if the petrol is gone flat the chainsaw simply won't start but there's still plenty lubrication.
However you also need to keep the air filter clean any tiny bits of crap getting in through air intake will also score the cylinder..

Been told this leads to carbon buildup in the cylinder

Turbohymac

Never had an issue of carbon build up..
I have a partner con saw and when I was buying it I was given the advice to always increase the oil from what's recommended. And the partner consaw should be throwing out a small amount of smoke when accelerated from tick over.. that came from a reliable dealer.
As for the manufacturer they hope that as soon as warranty runs out your engine will feck up otherwise the manufacturer ain't making any sales..
Adding a bit extra oil unfortunately don't work for very small engines like strimmer. They won't accelerate fully..
As for the Aspen fuel I've never tried it but a few years back it was fairly expensive and you still need to mix the oil ratio.

Thepillowman

Turbohymac wrote: »

Never had an issue of carbon build up..
I have a partner con saw and when I was buying it I was given the advice to always increase the oil from what's recommended. And the partner consaw should be throwing out a small amount of smoke when accelerated from tick over.. that came from a reliable dealer.
As for the manufacturer they hope that as soon as warranty runs out your engine will feck up otherwise the manufacturer ain't making any sales..
Adding a bit extra oil unfortunately don't work for very small engines like strimmer. They won't accelerate fully..
As for the Aspen fuel I've never tried it but a few years back it was fairly expensive and you still need to mix the oil ratio.

Just my tuppence worth but I was always told by dealers if its 50:1 use 50:1. The manufacturer knows from years of research and development what works.
Also Aspen comes pre mixed, quote from there website,
Aspen 2 is alkylate petrol premixed at 50:1 with a premium quality biodegradable 2-stroke oil. Suitable for chainsaws, clearing saws, hedge trimmers, power cutters and other land-based 2-stroke engines.

J.O. Farmer

Turbohymac wrote: »

As for the Aspen fuel I've never tried it but a few years back it was fairly expensive and you still need to mix the oil ratio.

The Aspen is still expensive but if you get the 2 stroke aspen you don't need to mix it.

If you're only using a gallon or 2 for the whole year it's probably worth it though.

Turbohymac

Thanks for that info on the aspen.. I might give it a try and compare against the regular petrol and oil mix..
Anyhow I don't think the petrol or Aspen was the issue with the original posters issue.