Checking on my JMS 066

[Frank bierce]

figured with all the hubbub...it's time to dive in and see what I'm in for. I have ran 3-4 tanks of fuel through this saw since getting it back. It got put on the back burner when I lost a coil before I had completed my second tank of fuel.


Already see some minor scoring developing...hopefully it isn't grindings...

 

[dall]

You need to get that apart before running much more

 

[sawmikaze]

I seriously wanna crack that guy.

 

[Canadian farm boy]

Is this the Christmas saw jms did a couple years ago?

Not that it really matters. Just curious.

 

[Frank bierce]

Is this the Christmas saw jms did a couple years ago?

Not that it really matters. Just curious.

Yes it is.

 

[Frank bierce]

 

[tree monkey]

twins

 

[Moparmyway]

Pics of the piston ?
That cylinder below the intake looks like a crapload of wear, and pepper spots too

 

[Frank bierce]

twins

Yep. Looks to be that way.
Not seeing any metal in here...which is good. Lol.

 

[TJ the Chainsaw Mechanic]

sad man, very sad

 

[Frank bierce]

Was already getting some rubbing..along with a few scratches

 

[Moparmyway]

Wait a minute ....... Dirko and a gasket ?

I'm thinking that with those dark spots on the base, its got some runout

 

[awol]

View attachment 83482 View attachment 83483

Ummmm......I hate to break it to you, but that jug has been "maxed out"!!!!

In more ways than one.........

 

[Frank bierce]

Ummmm......I hate to break it to you, but that jug has been "maxed out"!!!!

In more ways than one.........

Will work for jugs!! Lol

 

[Moparmyway]

Look at the uneven wear on the exhaust side, piston is rocking in the bore, wings are crossing the widened lowers and grinding itself into the dust thats scored your piston

 

[Frank bierce]

Please excuse my newbieness...but will that much extra area for the charge trying to come up from the case, push the cylinder over to the exhaust side like that? Seems to me, the charge coming up the transfer ports work against each other to keep the piston stable. With these fingers/arms pushing on the intake side, I see it being able to push the piston, mainly the bottom, ever so slightly towards the exhaust side?

 

[tree monkey]

Look at the uneven wear on the exhaust side, piston is rocking in the bore, wings are crossing the widened lowers and grinding itself into the dust thats scored your piston

I think your right, off cut base side to side

 

[Frank bierce]

Sure be curious to see what runout is on this.

 

[Frank bierce]

Here is a photo of the base with a paper towel to cover the distraction within.
Looks like it may have been cut on a table sander with the looks of the swirl marks.

 

[dall]

Here is a photo of the base with a paper towel to cover the distraction within.
Looks like it may have been cut on a table sander with the looks of the swirl marks.
View attachment 83490

That's how mine was also