Seized chainsaw

[oldballs]

Last winter I had a similar post when my MS290 (20" bar) "quit running" as I was cutting a 30 inch Pine stump right at ground level. After it colled down (it was smoking) it had very little compression and I couldn't get it started again. I took it to a friend who gave it back to me running fine at acceptable compression at no charge. He didn't take it apart nor replace any parts. I really don't know "what happened" nor what he did to it.

Cheers,
Mike

 

[MossRoad]

After 40 years of working around loggers I have never seen or heard of such a thing. Everyone starts and runs full throttle during cold or warm weather. The only saw motors I’ve ever seen seized was due to lubricant failure.

I drag raced a Yamaha RD400 2-stroke twin for about 10 years. Did all of my own engine and carb work. Pretty heavily modified bike. I had an occasion where I pulled it out of the garage, Gave it a kick to start it, the throttle cable did not return and got stuck full open, and it went from zero to a billion RPMs in about half a second, then PINNNG! It stopped. Seized solid. Upon dissection, the cylinders were scored heavily. It wasn't from no fuel or improper lubrication. It was from cold start to high RPMs instantly.

I can guarantee you that the loggers you know never do that to a cold saw. They give it a pull, it fires up to an idle speed, they pop the throttle a few times, wait a couple seconds, pop it again a few times, then go off to work. Those few seconds of warming it up make a huge difference.

 

[jyoutz]

I drag raced a Yamaha RD400 2-stroke twin for about 10 years. Did all of my own engine and carb work. Pretty heavily modified bike. I had an occasion where I pulled it out of the garage, Gave it a kick to start it, the throttle cable did not return and got stuck full open, and it went from zero to a billion RPMs in about half a second, then PINNNG! It stopped. Seized solid. Upon dissection, the cylinders were scored heavily. It wasn't from no fuel or improper lubrication. It was from cold start to high RPMs instantly.

I can guarantee you that the loggers you know never do that to a cold saw. They give it a pull, it fires up to an idle speed, they pop the throttle a few times, wait a couple seconds, pop it again a few times, then go off to work. Those few seconds of warming it up make a huge difference.

Many fire at full throttle, then let idle to warm up. I would still bet that the OP’s issue is due to lubrication.

 

[MossRoad]

Many fire at full throttle, then let idle to warm up. I would still bet that the OP’s issue is due to lubrication.

Sure. Most of the time that's the cause and the first thing to consider. However, someone stated it's the only cause, and it's not.

 

[jyoutz]

Sure. Most of the time that's the cause and the first thing to consider. However, someone stated it's the only cause, and it's not.

OK.

 

[marhar]

If you didn’t run the proper 2 cycle oil mix in your gas, then your saw is now a doorstop.

I agree. Too little oil will cause one to run hot (I made a dumb mistake in measuring and know). I made my mistake while cutting a cherry stump with a dull blade.

Take the plug out and see if you see fine metal shavings. If you see metal shaving you have a saw to part out.

 

[jyoutz]

I agree. Too little oil will cause one to run hot (I made a dumb mistake in measuring and know). I made my mistake while cutting a cherry stump with a dull blade.

Take the plug out and see if you see fine metal shavings. If you see metal shaving you have a saw to part out.

I have always tried to err on the side of extra oil. The only impacts of a slightly heavier oil/gas mix is a fouled spark plug and slightly reduced performance.

 

[MossRoad]

I have always tried to err on the side of extra oil. The only impacts of a slightly heavier oil/gas mix is a fouled spark plug and slightly reduced performance.

Too much oil in the gas and you can get a contract with the county fogging for mosquitos.

 

[jyoutz]

Too much oil in the gas and you can get a contract with the county fogging for mosquitos.

True. I use slightly more, not an excessive amount.

 

[RandyT]

I have always tried to err on the side of extra oil. The only impacts of a slightly heavier oil/gas mix is a fouled spark plug and slightly reduced performance.

The saw manufacturers will tell you that adding extra oil displaces the gas causing a lean run condition Now with that being said I have thought that even doubling the oil in the mix only results in a 2% change in gas/oil ratio. And if that 2% causing a lean failure you had problems before you even started.

 

[jyoutz]

The saw manufacturers will tell you that adding extra oil displaces the gas causing a lean run condition Now with that being said I have thought that even doubling the oil in the mix only results in a 2% change in gas/oil ratio. And if that 2% causing a lean failure you had problems before you even started.

That’s my thoughts too. I only add slightly more oil, not an excessive amount.

 

[xyz123]

Not if you tune carb to the mix your running. Been running 40:1 forever and 32:1 when ported stuff back in the day.

OEM has to tell you this stuff and to run 50 because of EPA. Read up on it. They have to tell you this, no ifs about it in US.

Carry on enjoyed the morning read and bickering in thread.

 

[RandyT]

That’s my thoughts too. I only add slightly more oil, not an excessive amount.

Not if you tune carb to the mix your running. Been running 40:1 forever and 32:1 when ported stuff back in the day.

OEM has to tell you this stuff and to run 50 because of EPA. Read up on it. They have to tell you this, no ifs about it in US.

Carry on enjoyed the morning read and bickering in thread.

Sometimes I really wonder how critical the mix ratio is. Up until the last few years saw manufacturers would tell you to double the mix ratio if using something other than there brand. So Solo/Dolmar/Stihl would say use 50:1 if using their oil but mix it at 25:1 for other brands. The new Poulan Pro premix gas says 40:1/50:1 on the can so which is it. And then the not as common now 1 mix pouches which was supposedly could be used to replace all mix ratios was 100:1.

 

[xyz123]

Sometimes I really wonder how critical the mix ratio is. Up until the last few years saw manufacturers would tell you to double the mix ratio if using something other than there brand. So Solo/Dolmar/Stihl would say use 50:1 if using their oil but mix it at 25:1 for other brands. The new Poulan Pro premix gas says 40:1/50:1 on the can so which is it. And then the not as common now 1 mix pouches which was supposedly could be used to replace all mix ratios was 100:1.

If you dont like your crank bearings or big end rod bearings etc run those epa thinner ratios. JMO

My dad tried that thinner ratio crap in his boat and couple seasons she was thump thump thump. I didnt know he had done it at the time. New used motor later because it was cheaper then rebuilding. I was like nooooooooooooooooooo.

But why we all make our own choices. Nobody selling me a saw is changing mine. I know they are mandated by EPA what they can say.

 

[oldballs]

What does the term "ported" mean when refering to chainsaw modifications? Thanx

Heck I still have some small cans of Homelite 1:16 oil for mixing.
Mike

 

[Helogabals]

don't forget to reed small print too
On oil can should be stated, that mix is good only few months.
Pro loggers dosnt feel that at all, but farmers might use their saws once in year. But that good old gas+oil mix from last time can be used only to light-up bonfire, no to be poured in saw.

 

[Snobdds]

More oil is good to a point, then it creates problems. More oil means more carbon. More carbon, especially on the exhaust port, means more scoring on a piston.

50:1 with modern oils is fine. Hell, I have a couple of old mccullochs that say 32:1. I just dump in my stihl premix in the can @ 50:1 and go.

Chainsaw bearings need just a good oil film. Any type of modern synthetic oil provides this...

 

[gstrom99]

What does the term "ported" mean when refering to chainsaw modifications? Thanx

Heck I still have some small cans of Homelite 1:16 oil for mixing.
Mike

Porting and muffler modifying is a way to "hop up" a saw. If not done right and carb is not adjusted for the mods, they are good ways to ruin a perfectly good saw. My saws have plenty of Ooomph the way the factory's spit them out. A sharp chain is the most important for performance. IMHO

 

[oldballs]

Thanx gs99.....That's where I'll stay too....no porting for me. Now, as I get older.....my issue is whether my "hands" have a enough Ooomph to "seize" the saw.

 

[MossRoad]

What does the term "ported" mean when refering to chainsaw modifications? Thanx

Heck I still have some small cans of Homelite 1:16 oil for mixing.
Mike

You alter the size of the intake, exhaust, and/or transfer ports to change the air/fuel flow and sometimes change the timing.

Sounds simple, eh?

Are you familiar with how a 2-stroke gas engine like on a chainsaw works? If not, there's a bunch of videos on youtube that show it. I'd find a good video, and a junk chainsaw. Watch the video and take apart the chainsaw. Really quite interesting as there's no valves to speak of. Just the position of the piston blocking and covering the different holes (ports) in the cylinder walls at different times, and the crank pushing the mixture around in the crank case. Kinda elegantly simple with few moving parts.