Monster saw works?

[Mastermind]

Have you ever had any problems with rings? A sharp edge on a ring can reek havoc in a cylinder too.

Nope. I've yet to see a ring that was problematic.

 

[Mastermind]

Have you ever had any problems with rings? A sharp edge on a ring can reek havoc in a cylinder too.

Of course, I rarely do any used saws. And if I do, I usually replace the rings.

 

[wcorey]

Between my own single experience as well as the recent ‘public hangings’, I’m beginning to see a pattern/common denominator involving sloppy piston to bore fit due to wear and/or ‘cleaned up’
pistons...

 

[Wilhelm]

A sloppy used piston has no business being utilized in a fresh port job!
In a fix/repair job maybe.

 

[Mastermind]

Between my own single experience as well as the recent ‘public hangings’, I’m beginning to see a pattern/common denominator involving sloppy piston to bore fit due to wear and/or ‘cleaned up’
pistons...

You might be onto something with this Bill.

Not necessary in disagreement, but in order to further help in understanding how something like this happens, I'd like to speak to your theory.

Piston to cylinder slop and ring breakage....or would skirt breakage be a more common issue in this situation? I've seen pistons with all the machine marks worn off in countless saws that had perfectly intact rings in place.

What I have seen in exhaust ports is the corners winding up too low, too high, or too tight because the person who created the port spent far too much time attempting to make a really nice looking finish, and in doing so changed the shape in an unintended way.

This was how I wound up building a ring hanger.

 

[huskihl]

70% width 385 with enough arch. Keep in mind I don’t know yet what “too flat” is. But my arch and much of the corner radius is usually within the aluminum portion of the piston above the top ring. The 390 in question seems to me to have too tight of corners and is extremely flat. I think if you’re going to have tight corners, you need to have more arch.

 

[wcorey]

You might be onto something with this Bill.

Not necessary in disagreement, but in order to further help in understanding how something like this happens, I'd like to speak to your theory.

Piston to cylinder slop and ring breakage....or would skirt breakage be a more common issue in this situation? I've seen pistons with all the machine marks worn off in countless saws that had perfectly intact rings in place.

What I have seen in exhaust ports is the corners winding up too low, too high, or too tight because the person who created the port spent far too much time attempting to make a really nice looking finish, and in doing so changed the shape in an unintended way.

This was how I wound up building a ring hanger.

Really not at all sure of the failure mechanism but could be due to resonance/harmonics, flapping the rings around or pushing on the lands making the rings stick a bit. Or something...
I hadn't thought of the ring breaking first and causing the hang-up but that still generally fits within the narrative.
I agree it would seem that skirt breakage would be the more likely scenario but maybe in some cases hanging a ring simply beats that to the punch.

My own experience was with an ms460 I ported and had cleaned up the mildly scored stock piston to use until I got a replacement, was a little loose in the bore but I was hot on trying out the saw.
I got lazy and ran the piston through multiple gtg's, eventually hanging the ring on the exhaust roof. The port had been fairly typically radiused and not excessively wide, as well as the chamfers looking fine so I was never sure just what happened in there.
Damage to the cylinder wasn't too bad so I cleaned it up and tossed in a meteor and in a short amount of time blew out an entire transfer bridge. Couldn't say as to the why there either though I can conjecture that the ring hanging episode caused some additional damage that got by me.

That one has just been my hard luck saw, porting wise...

 

[Mastermind]

Really not at all sure of the failure mechanism but could be due to resonance/harmonics, flapping the rings around or pushing on the lands making the rings stick a bit. Or something...
I agree it would seem that skirt breakage would be the more likely scenario but maybe in some cases hanging a ring simply beats that to the punch.

My own experience was with an ms460 I ported and had cleaned up the mildly scored stock piston to use until I got a replacement, was a little loose in the bore but I was hot on trying out the saw.
I got lazy and ran the piston through multiple gtg's, eventually hanging the ring on the exhaust roof. The port had been fairly typically radiused and not excessively wide, as well as the chamfers looking fine so I was never sure just what happened in there.
Damage to the cylinder wasn't too bad so I cleaned it up and tossed in a meteor and in a short amount of time blew out an entire transfer bridge. Couldn't say as to the why there either though I can conjecture that the ring hanging episode caused some additional damage that got by me.
That one has just been my hard luck saw, porting wise...

Someone sent me a message (I sorta wish they would have posted in the open forum) about how they have seen a well worn piston wind up looking like a ring had hung......and I can see it happening exactly as they described. Piston tilts forward enough for the edge of the crown to start dinging the top of the exhaust port.....and finally, broken rings and lands.

To me, this has become a great thread. Very civil, and informative.

 

[Mastermind]

70% width 385 with enough arch. Keep in mind I don’t know yet what “too flat” is. But my arch and much of the corner radius is usually within the aluminum portion of the piston above the top ring. The 390 in question seems to me to have too tight of corners and is extremely flat. I think if you’re going to have tight corners, you need to have more arch.

View attachment 286063

You do nice work for a guy with overly fat fingers.

 

[jacob j.]

You do nice work for a guy with overly fat fingers.

He really should have been a proctologist.

 

[trooney]

D

He really should have been a proctologist.

Doesnt he moonlight as one?? !!

 

[Mastermind]

He really should have been a proctologist.

If the doctor that was doing my prostate exam walked in with hands like Kevin's, I'd be like....

JUST SAY NO !!!!!!

 

[Stump Shot]

Between my own single experience as well as the recent ‘public hangings’, I’m beginning to see a pattern/common denominator involving sloppy piston to bore fit due to wear and/or ‘cleaned up’
pistons...

You might be onto something with this Bill.

Not necessary in disagreement, but in order to further help in understanding how something like this happens, I'd like to speak to your theory.

Piston to cylinder slop and ring breakage....or would skirt breakage be a more common issue in this situation? I've seen pistons with all the machine marks worn off in countless saws that had perfectly intact rings in place.

What I have seen in exhaust ports is the corners winding up too low, too high, or too tight because the person who created the port spent far too much time attempting to make a really nice looking finish, and in doing so changed the shape in an unintended way.

This was how I wound up building a ring hanger.

You see this quite a bit even on the forum here. Guys want a Hi Performance saw, yet are too cheap to replace a worn out/messed up piston. With threads like, can I clean this up/run this etc. and so on. Before a fella can say no, fifty guys have come along and said I'd run it. Who at that point wants to jump into that hornets nest. We only have to look at the A and B sometimes C and D cylinders with matched pistons. With differences of .0005", and now you want to sand and file and run it? Good luck. When it goes up and down for a bit success is claimed and no further reports. A piston has to transfer heat to the cylinder wall to survive. this is why they are sized the way they are. A quick test of how well your used piston is fairing is the drop test. Without ring/s put the piton in the cylinder(with spark plug and decomp holes blocked) and let the piston go, once past the exhaust port it should slowly float down to the top of the head. If it drops like a rock, it's too worn and a new one should be installed. With several good makers out there including OEM there's really no good reason not to. Unless you find yourself working on a 1940-1950's era saw with no chance of finding a new piston, some trickery can be performed to possibly bring it back into working spec, the time and effort is not worth so on a modern power saw with many $$$ options available to fit even the tightest of budgets, I know, I have to squeeze them in quite often for folks.
As far as this ring hanging thing is concerned I would kindly reserve judgement as a good inspection is not possible here and this isn't one of our "OPE builders", so my concern level isn't elevated at all. Just what we're supposed to do for the OP is unclear, other than start a mudslinging internet war about someone I know nothing of.
Carbon build up can also play havoc with rings not allowing them to retreat into the lands properly. Many ways to kill a saw.
I consider myself one of the fortunate few that have yet to have one hang, with a pile-O-saws out there it can still happen, even as conservative as I am with my exhaust ports it could still happen, all I can say is if and when that day comes, the first words out of my mouth will be "bring/send me the saw".

 

[mdavlee]

You ain’t pushing hard enough if you don’t have g a ring or two[emoji23] I’ve had some not even make a warm up and destroy themselves. That’s one advantage the steel rings and Wiseco pistons do give.

 

[Stump Shot]

You ain’t pushing hard enough if you don’t have g a ring or two[emoji23] I’ve had some not even make a warm up and destroy themselves. That’s one advantage the steel rings and Wiseco pistons do give.

For a play/gtg type saw this is great, there's zero upside to pushing the limits on a work type saw that I can see, nor have i ever been asked to do by anyone.

 

[mdavlee]

For a play/gtg type saw this is great, there's zero upside to pushing the limits on a work type saw that I can see, nor have i ever been asked to do by anyone.

I always want to give their money’s worth and ask if they want a plain work saw or more.

 

[wcorey]

You see this quite a bit even on the forum here. Guys want a Hi Performance saw, yet are too cheap to replace a worn out/messed up piston. With threads like, can I clean this up/run this etc. and so on. Before a fella can say no, fifty guys have come along and said I'd run it. Who at that point wants to jump into that hornets nest. We only have to look at the A and B sometimes C and D cylinders with matched pistons. With differences of .0005", and now you want to sand and file and run it? Good luck. When it goes up and down for a bit success is claimed and no further reports. A piston has to transfer heat to the cylinder wall to survive. this is why they are sized the way they are. A quick test of how well your used piston is fairing is the drop test. Without ring/s put the piton in the cylinder(with spark plug and decomp holes blocked) and let the piston go, once past the exhaust port it should slowly float down to the top of the head. If it drops like a rock, it's too worn and a new one should be installed. With several good makers out there including OEM there's really no good reason not to. Unless you find yourself working on a 1940-1950's era saw with no chance of finding a new piston, some trickery can be performed to possibly bring it back into working spec, the time and effort is not worth so on a modern power saw with many $$$ options available to fit even the tightest of budgets, I know, I have to squeeze them in quite often for folks.

From my angle I see this as an overly reactionary and exaggerated response and just one opinion coming from a very narrow perspective of the topic.

I and many others on the forums know how to measure piston/bore clearances and to make an informed decision to what’s acceptable given whatever the expectations are for the outcome. The relatively few posts I see inquiring about usability of a cleaned up piston (as opposed to cylinders) often have someone chiming in about a simple visual check of the skirt thickness and a shim based clearance check.

I’m a pretty advanced saw hoarder so have a lot of saws to deal with even by forum standards, so yes, buying many dozens of pistons over and above the dozens I already buy can actually become somewhat cost prohibitive. I generally don’t sell even to support my habit so saws aren’t going out to customers with expectations of factory new type longevity or whatever.
I’m also a cheap-ass who invariably holds out for cheap deals so very often a new piston costs more than I have into the saw that I may be slapping together just to see how it runs and to access if I want to put more $'s/effort into it.

I have plenty of saws with cleaned up pistons with machine lines still on most of the skirt where clearance was only minimally affected by a bit of cleanup on a patch of skid marks. I also have play/beater saws where I’m well aware I’m pushing the bounds of mechanical stability, that have far exceeded all my expectations and that 460 is/was one of them…

As far as this ring hanging thing is concerned I would kindly reserve judgement as a good inspection is not possible here and this isn't one of our "OPE builders", so my concern level isn't elevated at all. Just what we're supposed to do for the OP is unclear, other than about someone I know nothing of.

The op isn't the one binging up the issues, just made in inquiry. The poster bringing up the issues is just answering the inquiry from what they've seen/experienced and doesn't own any of the saws in question.
So, sort of "Just what we're supposed to do for the OP".
Seems like we're having a fairly neutral and interesting discussion about the pictures and description of the problems as presented and I see no "mudslinging internet war" here.
Yet... lol...
If anything it would seem you're the one trying to start something.

 

[Stump Shot]

I always want to give their money’s worth and ask if they want a plain work saw or more.

I blame @Mastermind he's the one that taught me.

 

[Stump Shot]

From my angle I see this as an overly reactionary and exaggerated response and just one opinion coming from a very narrow perspective of the topic.

I and many others on the forums know how to measure piston/bore clearances and to make an informed decision to what’s acceptable given whatever the expectations are for the outcome. The relatively few posts I see inquiring about usability of a cleaned up piston (as opposed to cylinders) often have someone chiming in about a simple visual check of the skirt thickness and a shim based clearance check.

I’m a pretty advanced saw hoarder so have a lot of saws to deal with even by forum standards, so yes, buying many dozens of pistons over and above the dozens I already buy can actually become somewhat cost prohibitive. I generally don’t sell even to support my habit so saws aren’t going out to customers with expectations of factory new type longevity or whatever.
I’m also a cheap-ass who invariably holds out for cheap deals so very often a new piston costs more than I have into the saw that I may be slapping together just to see how it runs and to access if I want to put more $'s/effort into it.

I have plenty of saws with cleaned up pistons with machine lines still on most of the skirt where clearance was only minimally affected by a bit of cleanup on a patch of skid marks. I also have play/beater saws where I’m well aware I’m pushing the bounds of mechanical stability, that have far exceeded all my expectations and that 460 is/was one of them…




The op isn't the one binging up the issues, just made in inquiry. The poster bringing up the issues is just answering the inquiry from what they've seen/experienced and doesn't own any of the saws in question.
So, sort of "Just what we're supposed to do for the OP".
Seems like we're having a fairly neutral and interesting discussion about the pictures and description of the problems as presented and I see no "mudslinging internet war" here.
Yet... lol...
If anything it would seem you're the one trying to start something.

Check out Traverse Creek at the top of the page, their hi perf piston line is quite well made more so than the money asked for them.
I didn't intend to start a quarrel with anyone, rather state my opinions like everyone else. My fault I should have known better.

 

[066 redeye]

You do nice work for a guy with overly fat fingers.

Like s well hung lesbian??