Gettin' all "Squishy" inside....

Laziness can be the mother of invention, and I was wondering if there is an yreason not to check squish as follows: Take a 3-4" long piece of electrical solder, slip it in through the plug hole till it contacts the front of the bore, slowly turn the saw over, pull the solder out, measure it. Then clip the mashed end off, bend the solder into a "C" shape, reinsert into the borework it over to the rear of the bore, possibly using the top of the piston to bend the wire into the right shape after it is in there, squishing it at the rear, remove,and measure the rear squish.

Seems the squish could be measured without removing the jug this way, so if a guy were contemplating removing the gasket to increase compression, he could know before taking things apart whether it would be feasible. Opinions? Thanks in advance.

Brace for impact

DOH!




yes.... :greenchainsaw:

BUT, when you measure, measure above the inlet and exhaust simultaneously.... or you'll not account for piston rock.


I prefer to place a strip of soft lead (some solder, particularly the lead-free types, can be way too hard..) in though the exhaust port, and hold it with axle grease.

And to think I've been filling my cylinders with plaster of Paris for all these
years then carefully grinding away all the aluminum until I'm left with nothing
but the plaster cast, then measuring that.
Teacherman, your way is the standard I think.

lololol

And we have impact.

Huston, we have successfully reinvented the wheel.

Use the Search function or................

Suffer the slings and arrows of outrageous AS members.
Don't worry, it is part of the new abuse.

thanks

I needed a laugh today.. lol

Yesterday I believe, read TW's reply...

http://arboristsite.com/showthread.php?t=77855&highlight=squish

Okay, you predators, ABUSE AWAY!!!!! :bringit: :chatter: HAHAHAH see if I care!!!:greenchainsaw:

I had always seen posts where people were describing squish testing AFTER the cylinder was removed, sticking little bits of solder to the piston with grease, then reassembling the p/c, turn the motor over, take the sucker apart, mic the solder slivers. So I was jest trynta save sumtime and sum case threads. So there!!!:sword: :fart: :hmm3grin2orange:

Oh, btw, my idea of vac testing with Gorilla duct tape works like a charm (insert "raspberry" smilie here)! So I have actually contributed something worthwhile, you jest hafta sort thru all the bovine ƒéçål matter to find it....

opcorn:

That is how I've always done it. I test front and back together and the both sides. That way piston rock doesn't come into the equation.

chainsawwhisperer said:

And to think I've been filling my cylinders with plaster of Paris for all these
years then carefully grinding away all the aluminum until I'm left with nothing
but the plaster cast, then measuring that.
Teacherman, your way is the standard I think.

Click to expand...

Why do I believe you are telling the truth?:greenchainsaw:

teacherman said:

Why do I believe you are telling the truth?:greenchainsaw:

Click to expand...

Maybe this is why none of my saws run!!

blsnelling said:

That is how I've always done it. I test front and back together and the both sides. That way piston rock doesn't come into the equation.

Click to expand...

OK, here is another possible dumba$$ question: Does the piston rock enough to slap the top of the cylinder if the cold squish is reduced to around .020"? What is normal "rock," so to speak?

Depends on how worth the piston skirt is, a new piston with just a couple thou clearance could only rock maybe 1 thou or less, a sloppy worn out piston I am sure could rock several thou.

The shorter the piston, the more they can rock.

teacherman said:

Does the piston rock enough to slap the top of the cylinder if the cold squish is reduced to around .020"? What is normal "rock," so to speak?

Click to expand...

I seriously doubt it would rock that much. 020" is the general rule of thumb that most people use as a safe number. You could test it by measuring the squish on at least two opposing sides and then measuring only one side.

So...Al Gore did invent the internet?

Many may rip on this thread, but I will bet as many learned something.

I noticed my Husky rocked out particurlarly hard after I swapped the stock gasket for a paper one. But then I never really ran it beforehand. Could just be it's a decent saw. Seems that way

You have to remember that the squish clearance measured cold this way, with all the clearances compressed by the solder can be considerably less at high revs no load, due to rod stretch and clearances being sucked the other way by deceleration forces. Whether it is high velocity gases or whatever, the piston top in the squish area starts to get pretty shiny if you go down around 14 thou. cold clearance!

:agree2:

And a shiny piston means that the boundary layer of gas that protects the piston is getting blasted away, leaving the metal to absorb much more heat.
Bad things happen next....