# why do you see so many chainsaws that have a scored piston?



## RIDGERUNNER30 (Jan 29, 2011)

I have a question to some of the experts on here, I go on ebay alot and look at all the cahinsaws and the other day won two off ebay a sthil 032av and a 028 wood boss both look to be a great shape and both stated to have high compression and are running, but my question what can you do to keep from scoring a piston? does this happen because owners don't mix the right ratio of oil and fuel or using the wrong kind of oil? and another question a sthil dealer told me to use only sthil oil in my saws, does it matter long as the mixture is right. the reason i guess i'am asking is is you see a alot of chainsaws for sell in this condition scored pistons and was wondering why.


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## Naandme (Jan 29, 2011)

Well I know one of the quickest ways to ruin one is to run without an air cleaner that will score a cylinder and piston super quick and you are correct not the right oil gas ratio can do it too.


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## smokinj (Jan 29, 2011)

straight gas!


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## southbound (Jan 29, 2011)

low octane gas,old gas,bad air filter and so on....


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## pen (Jan 29, 2011)

My stihl weedwacker's owner manual (now mind you, it's about 14 years old now) it says to run 50:1 if using stihl oil and 32:1 if using any other brand.  It's book also recommends high octane gasoline.

To keep things fresh considering ethanol fuel can go stale quicker, I only make at most 2 gallons of fuel at a the beginning of the season.  As things start winding down I only make gallon batches.  

It may cost a few cents more per gallon but I purchase the huskvarna mix for my husky saw in the pre-measured containers.  My dealer sells them cheaper if you buy by the 6 or 8 pack (i can't remember which).

When I want to use my equipment I want it to work well and work now.  Things tend not to break when they are not in use.  If my saw goes down and I've got wood that needs to be taken care of I have to waste time dropping the saw off at the shop then either rent or borrow one (and hope I don't break theirs) then pay for the repair bill to boot.

Too me, a little extra for good maintenance is actually a money saver in the long run. 

pen


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## smokinj (Jan 29, 2011)

pen said:
			
		

> My stihl weedwacker's owner manual (now mind you, it's about 14 years old now) it says to run 50:1 if using stihl oil and 32:1 if using any other brand. It's book also recommends high octane gasoline.
> 
> To keep things fresh considering ethanol fuel can go stale quicker, I only make at most 2 gallons of fuel at a the beginning of the season. As things start winding down I only make gallon batches.
> 
> ...




Your on track. I only mix a gallon at a time with very thirsty saws. You can use your old one shots and fill them back up with the quart bottles. (Gooserider trick) Been doing that for a long time now.


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## DanCorcoran (Jan 29, 2011)

Never mind, I figured it out...


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## CTYank (Jan 29, 2011)

RIDGERUNNER30 said:
			
		

> I have a question to some of the experts on here, I go on ebay alot and look at all the cahinsaws and the other day won two off ebay a sthil 032av and a 028 wood boss both look to be a great shape and both stated to have high compression and are running, but my question what can you do to keep from scoring a piston? does this happen because owners don't mix the right ratio of oil and fuel or using the wrong kind of oil? and another question a sthil dealer told me to use only sthil oil in my saws, does it matter long as the mixture is right. the reason i guess i'am asking is is you see a alot of chainsaws for sell in this condition scored pistons and was wondering why.



Not claiming to be an expert, but I've only seen one scored (w/melted crown) piston in many years; that was caused by an idiot kid who rocked the chain and continued to run it hard on straight gas, then asked later what all the smoke meant. "Straight-gassing" means NO oil mixed with fuel.

There's all manner of scoring, and degrees of severity, from "run it hard on straight gas" and junk it to "suck a little dust" and burnish the piston. There's also "keep 'er working with leaking crank seals" and cook a piston from leanness.

Good quality 50:1 oil used @ 50:1 works fine except for engines with plain-bearing journals, and you won't find such for sale. Marketing PR aside, brand means zilch.

So, to your first question: Use only fresh mix w/proper ratio (if in doubt, drain it into the mower), inspect intake connections from engine to air filter regularly, and deal with the problem NOW if you suspect high speed mixture problems or crankcase leaks. You'll find many discussions "out there" on the latter; be attentive to changes in how the engine runs.


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