Chainsaw with scored piston. How?

[Jstpssng]

I like chainsaws when they run... when they stop I upgrade to a new one. I've only had 8 saws in my life including my current Husky and a Poulan which I use for a backup. I've used a few others on various jobs; I loved my Partner 5000, even if I did almost take my leg off with it. Oh to be young and dumb again.

 

[ericm979]

Not sure I can tell the difference in 2 stroke oils either. How would you?

Disassemble the engine, look at the parts and measure the wear. I ran Motul 800 synthetic in my two stroke road race and street motorcycles and had opportunities to examine engine parts. The only lubrication based failure was when an oil injection line on my RZ500 got kinked during installation due to my error. That piston's sitting on my desk as a reminder. In off road competition (observed trials) the smell of the Motul was getting complaints from other competitors. I switched to Redline Allsport synthetic. It also worked well with no failures and the exhaust smells better. I've continued to use it on my saws.

 

[Stimw]

I bought a case of oil for my outboard motor and just use it in my 2 cycle engines.
If it is good enough for up to $20,000. engines then it will work on those toys.
Still use Echo oil in my saw though with it's own gas can.

 

[turbo36]

Just remember, when you change the oil ratio, you are also changing the fuel/air ratio. With more oil, you are LEANING the amount of gasoline in the mix. Think of it this way, the fuel jet only allows so much liquid through it and if there are more oil molecules, there are less gas molecules. An already lean engine is really going to suffer with that oil ratio unless the carb is modified.

Absolutely correct!

 

[kthompson]

I had a smaller stihl same happened to and still under warranty but was told no warranty on that as it was my fault over heating the saw. Bull. Had friend tell me you could not have held onto that saw if it ran that hot and I agree. Two points, another shop bout parts off ebay and repaired it but did send complaint to stihl who had dealer buy it back. It had been in their shop several times for did not want to run and in the process they had adjusted the fuel mixture. Bought a model or two up and very pleased with it.

 

[JimRB]

I heard one of my neighbors running a chainsaw. Full throttle, maybe I heard the rev limiter when they were using it. Not the way I run a saw. Full throttle when I am in stuff big enough to bog the saw down a bit. I thought I had seen pictures or comments in the past about piston scuffing from unnecessary wide open throttle but maybe not. I use high test gas, Stihl oil in the silver bottle at 50-1, fuel may sit for 6 months or more. I cannot say that I have anything that will not start among the 5 Stihl engines. Heck I had 5 year old gas in my generator that started every time I did a test start which might be 6 months to a year between starts. I would turn off the fuel cutoff valve and let the engine empty the carb. No fuel stabilizers in that fuel. Yes, I play with fire. That said I have had to remove the carbs and clean them up on my Dad's equipment. I think he bought low test fuel for the mower and tractor.

 

[arrow]

Where on the piston and scoring characteristics can tell you what happened. Most saws score on the exhaust side from over heating or fuel ratio problems. Bad gas and over heat look about the same. Intake side scoring has more to do with faulty filtration.
What I saw many times in my career were saws that were using premium fuel that had a lot of cleansing additives in it. Combine this with a saw that was over revving as a result of too lean screw settings and you got washed out cylinders that quickly deteriorated.
Also, not all canned fuels are equal. Buy the good stuff from a dealer as opposed to that Trufuel crap Wally World sells.
Any saw should not be rev screaming and never tune or have tuned a saw to go as fast as it can.

 

[PILOON]

I decided to overhaul a couple of 2 strokers, a chain saw and weedeater. Afterwards, I decided that the only reason I was experiencing engine damage was that I wasn't getting enough lubrication. So, in buying new replacements, I still use synthetic oil and rather than 40 or 50:1, per the mfgrs recommendations, I run more like 25-30 to 1 (rather than a bottle to a gallon, I use a bottle and a half per gallon) and being synthetic, smoking is seldom visible. We'll see how that works out as the machines age.

A bit too much oil really wont hurt a 2 cycle other than messing up the spark plug, and that's cheap to replace.
OK, maybe a bit of smoke but that'll keep the biting bugs away. LOL.

IMO they are getting a bit to lean on the oil these days.
Engineers simply trying to meet California 'smog' regs perhaps?
Then there is the consideration that 2 strokes are by design lighter weight than a 4 stroke due to less parts.
The saw engineers fully understand that a saw user simply does not want to us a saw (4 stroke) that weighs twice the weight or a 2 stroke and is attempting to meet the smog (environment) regulations.
There is simply no way you will get 4 stroke chain saw to ever outperform 2 stroke.

Use oil and simply change spark plugs when the saw gets sluggish or hard to start.
Plugs are cheap!
Back when, the oil mixes were much richer and we never had seized or scored pistons.

 

[Texasmark]

Just remember, when you change the oil ratio, you are also changing the fuel/air ratio. With more oil, you are LEANING the amount of gasoline in the mix. Think of it this way, the fuel jet only allows so much liquid through it and if there are more oil molecules, there are less gas molecules. An already lean engine is really going to suffer with that oil ratio unless the carb is modified.

Good point but: A 124oz gallon of gas gets a 2.7 oz bottle of oil per directions on Stihl silver bottles. Boosting by 50% is just 1.35 oz or right at 1%. Doubt that will make any difference especially with my running premium fuel.

 

[arrow]

Back when, the oil mixes were much richer and we never had seized or scored pistons.

Back when, we never had chainsaws running as fast as they are now. The old McCullochs and Homelites I used to use were lucky to have chain speeds of over 8000 rpm.
With manufacturers making smaller saws with as much power as the old larger ones, speed is critical. The old saying "nothing beats cubic inches" is not quite true as rpm's can certainly over come c.i. deficiencies.
Old saws, being way slower, were much less susceptible to fuel ratios, gas quality or chemical configuration and poor or uninformed cutting techniques than exist today.

Speaking of speed. Anyone want to buy the 763 mph Blood Hound race car with the Rolls Royce jet engine? Only $250,000.