Inside the Exploded JMS 064

[blsnelling]

Could it have spit the circlip off and jambed the piston? It 's pretty odd for a rod failure on a Stihl chainsaw unless it jambs .Briggs and Stratton engines blow rods not Stihls .

I've always figured the lightened piston failed first.

 

[RIDE-RED 350r]

I've seen some engine carnage on various things in my day, but wow!!

Funny, I have seen more than a couple folks say his port work is good. Doing good port work takes patience and care. Strange that he drops the ball on general assembly. I'm not saying this to dispute the findings of the recipients of this shoddy work in any way. Just an observation of the oddity that he does good port work but neglects the rest.

 

[tree monkey]

 

[malk315]

I've seen some engine carnage on various things in my day, but wow!!

Funny, I have seen more than a couple folks say his port work is good. Doing good port work takes patience and care. Strange that he drops the ball on general assembly. I'm not saying this to dispute the findings of the recipients of this shoddy work in any way. Just an observation of the oddity that he does good port work but neglects the rest.

I've had the same exact thought after reading all of these threads that show saw after saw with bad threads and the like. Since port work takes being meticulous you would think he would be meticulous about things besides port work -- such as simply confirming a screw has the threads at least started well so they don't be buggered. Wow.
I can't stand buggered threads... huge pet peeve for me.

Carry on!

 

[VinceGU05]

wow!! that did a better job than when i blew my 084 up when the connecting pin slid out into the ports at high revs.
looks like something similar has happened.

 

[Frank bierce]

Yeeessssss!!!! Lol.

 

[drf256]

My bet is that Jason assembled that case. I'm pretty sure he had it powdered and then he assembled.

Jason used a ball hone on his cylinders. I use a hone routinely, and I don't get that awful pattern he does. I use a fine 3 stone though.

My bet is that his failures are from piston/crank/pin bearing side loading from poor machining. The lightened pistons and AM parts just fall apart quicker that the sturdier OEM parts would.

If you're tossing that case, I'd like a shot at repairing it.

 

[Al Smith]

Probably never really know .However if you look at the piston face at about 1 o'clock you can see a ding like it ingested something .

 

[Tor R]

My bet is that Jason assembled that case. I'm pretty sure he had it powdered and then he assembled.

Jason used a ball hone on his cylinders. I use a hone routinely, and I don't get that awful pattern he does. I use a fine 3 stone though.

My bet is that his failures are from piston/crank/pin bearing side loading from poor machining. The lightened pistons and AM parts just fall apart quicker that the sturdier OEM parts would.

If you're tossing that case, I'd like a shot at repairing it.

I also sit thinking how he manage to make those pattern Doc (almost look like his ball hone is defect since he manage to make the pattern close to the top of the jug)
The 3 shoe hone you use, what grit does it have? P150, P180, P220?

 

[drf256]

I think it's 320 Tor.

I spray WD40 in the jug, hone, wipe clean. Then follow it with a scotchbrite hone.

 

[Keith Gandy]

Schnikeys- I had that happen once on an 046 that I lightened the piston too much on. Luckily it was my own saw, but it was still painful- Crank, case, piston, tank- all garbage.

Which IMO is what happened here . Piston was alil too light. I ran this saw when my buddy John got it from JMS and it ran really well but lacked alil bottomend for my taste

 

[srcarr52]

It's hard to tell from what's left of the piston but I'm pretty sure I've lightened pistons further than that without them exploding. So there must be another reason for this mess.

 

[Mastermind]

In my humble opinion it's impossible to be sure of what really happened. I've never really liked these sort of threads because everyone adds their thoughts and ideas from just seeing a few pictures. People begin to blame the builder, the operator, the parts manufacturer, hurricane Irma, etc.....

It's just a saw that blew up. Mess with these things long enough, and we all will see one come unglued.

 

[astnmacgto]

In my humble opinion it's impossible to be sure of what really happened. I've never really liked these sort of threads because everyone adds their thoughts and ideas from just seeing a few pictures. People begin to blame the builder, the operator, the parts manufacturer, hurricane Irma, etc.....

It's just a saw that blew up. Mess with these things long enough, and we all will see one come unglued.

Carnage is what's up...... IF........ It's due to testing the limits of what some thing is capable of.

However, not cool if the carnage is due to carelessness.

In this case (pun intended) no one knows for sure.

 

[astnmacgto]

However I must also ad, carnage should be in the research and development stage only. And r+d should never be part of the final product/ customer paid stage

 

[Mastermind]

However I must also ad, carnage should be in the research and development stage only. And r+d should never be part of the final product/ customer paid stage

In other words...

To make an omlet, you gotta break a few eggs.

But nobody wants egg shells in their omlet.

 

[astnmacgto]

In other words...

To make an omlet, you gotta break a few eggs.

But nobody wants egg shells in their omlet.

I sure do love a well constructed, visually pleasing omelette, made with quality ingredients by someone who has learned how to make a great one every time

 

[MustangMike]

In my humble opinion it's impossible to be sure of what really happened. I've never really liked these sort of threads because everyone adds their thoughts and ideas from just seeing a few pictures. People begin to blame the builder, the operator, the parts manufacturer, hurricane Irma, etc.....

It's just a saw that blew up. Mess with these things long enough, and we all will see one come unglued.

I'll agree that it is impossible to ever know for sure what happened, but when about 10 out of 10 of his jugs that were tested were not square with the bore, IMO, speculating that this may have been the cause is not out of bounds and is entirely reasonable.

It is really a wonder that more saws do not blow up at 15,000 RPM!

 

[T.Roller]

In my humble opinion it's impossible to be sure of what really happened. I've never really liked these sort of threads because everyone adds their thoughts and ideas from just seeing a few pictures. People begin to blame the builder, the operator, the parts manufacturer, hurricane Irma, etc.....

It's just a saw that blew up. Mess with these things long enough, and we all will see one come unglued.

It's Trump's fault you big dummy!

 

[Mastermind]

I'll agree that it is impossible to ever know for sure what happened, but when about 10 out of 10 of his jugs that were tested were not square with the bore, IMO, speculating that this may have been the cause is not out of bounds and is entirely reasonable.

It is really a wonder that more saws do not blow up at 15,000 RPM!

But.....9 out of those 10 didn't come apart.

So...????