STIHL The Official Stihl Chainsaws Thread

[bigbadbob]

More pics

 

[bigbadbob]

And some more...

 

[Al Smith]

The rings aren't seated yet .Flog it like a rented mule,it will come around

 

[PogoInTheWoods]

Decomp may be leaking. Replace it with a bolt/plug and see if that makes any difference.

 

[bigbadbob]

The rings aren't seated yet .Flog it like a rented mule,it will come around

Ya think it will go up that much??? like 30-40psi?? Already a good hard tank thru it.

Decomp may be leaking. Replace it with a bolt/plug and see if that makes any difference.

Already plugged and checked.

 

[Al Smith]

May ,may not .When I did the 038 mag a few years back using Cabers it started out a tad low .It must have taken me 2 months of cutting up long lengths of oak down from about ten cords one of the trimmers gave me .Ten 15 minutes each time .It finally got up to about 170 -180 PSI .With a well used cylinder it's no longer perfectly round .BTW that saw engine was modified else it wouldn't be that high .

 

[Maintenance Chief]

Ya think it will go up that much??? like 30-40psi?? Already a good hard tank thru it.

Already plugged and checked.

It has already been ground on by someone obviously.
They could have raised the exhaust port so high that its breaking the seal with very little blow down.

 

[PogoInTheWoods]

That piston just may be clapped out beyond rings being much help. You could check your skirt clearance against the specs, but if the machining marks are gone I'd stick another piston in the rascal and go from there.

Any chance that porting may have gotten a little out of hand and is having an unintended effect?

 

[Al Smith]

I might further add when I made a cast iron cylinder liner for a 125 McCulloch at least 15 years ago as of yet I don't have the tool steel rings seated .But it still has plenty of power but you don't need to use the decomp .Usualy on that model you just about have to use the decomp unless you have arms like a gorrila .

 

[bigbadbob]

My thoughts are on the raised ex.
Comp was the same with both sets of rings,,,
I will do some checking.
Anybody know what the cleanace is on the skirt.
I did have a 066 that the skirt was so thin you could shave with it,,, it still ran good.
And thanks

 

[bigbadbob]

So i got 4 thou between jug and slug 5 thou wont go.
Slug measures from skirt up,, four places 53.92 54 54 53.85
Im assuming all is good??
guess i gotta find a jug.

 

[Woodslasher]

@huskihl or @Mastermind I may be asking the impossible, but does that jug look fubared?

 

[huskihl]

So i got 4 thou between jug and slug 5 thou wont go.
Slug measures from skirt up,, four places 53.92 54 54 53.85
Im assuming all is good??
guess i gotta find a jug.

Can’t speak for an 066, but .004 –.005 is about the limit for clearance on a 395 before the piston starts to rattle. If it’s not rattling at an idle, it’s unlikely that is your issue.

The cylinder looks like it was “ported“ by someone without proper tools. It’s got no machine work done to it and it looks like the exhaust is raised way up which is bleeding off your compression. And I know for a fact that the Mickey Mouse ears in the top of the intake on an 066 cylinder are going backwards. It will run better with the roof 5° lower than stock rather than being opened up higher. All the ears do is slow down the incoming charge and direct it to nowhere.

 

[bigbadbob]

Can’t speak for an 066, but .004 –.005 is about the limit for clearance on a 395 before the piston starts to rattle. If it’s not rattling at an idle, it’s unlikely that is your issue.

The cylinder looks like it was “ported“ by someone without proper tools. It’s got no machine work done to it and it looks like the exhaust is raised way up which is bleeding off your compression. And I know for a fact that the Mickey Mouse ears in the top of the intake on an 066 cylinder are going backwards. It will run better with the roof 5° lower than stock rather than being opened up higher. All the ears do is slow down the incoming charge and direct it to nowhere.

thanks,,,,
and thanks for explaining it. I bet your diag is spot on.

 

[Al Smith]

FWIW on McCulloch around 4 thou clearance is about standard to a max of 10 thou .I have no idea about the rest of them ..But keep in mind that's the skirt which will have a slight taper skirt to right below the rings in the crown .Some say no but they don't have a real good set of mics IMO .

 

[Mastermind]

So new cabers,, ran a tank thru,, still not up to snuff,, comp was about 130 again WTF
squish 22-28 ,, 10thou BG Looks like somebody ground on the jug,,,,

Exhaust is too high.

It has already been ground on by someone obviously.
They could have raised the exhaust port so high that its breaking the seal with very little blow down.

This.

Can’t speak for an 066, but .004 –.005 is about the limit for clearance on a 395 before the piston starts to rattle. If it’s not rattling at an idle, it’s unlikely that is your issue.

The cylinder looks like it was “ported“ by someone without proper tools. It’s got no machine work done to it and it looks like the exhaust is raised way up which is bleeding off your compression. And I know for a fact that the Mickey Mouse ears in the top of the intake on an 066 cylinder are going backwards. It will run better with the roof 5° lower than stock rather than being opened up higher. All the ears do is slow down the incoming charge and direct it to nowhere.

And all this.

 

[bigbadbob]

Exhaust is too high.

This.

And all this.

Thanks you sir...
Thanks all of you,, yer the best.
Found a oem jug and its on its way.
Will check in later.

 

[Al Smith]

Don't give up the ship .You could shave the base to gain some more compression .Put it back together leaving the rings off then measure the port and go from there . Just guessing I'd say stock would be some where around 99-100 degrees of rotation .Although I've never done it if you don't have access to a lathe you probabley could use sandpaper over a piece of plate glass but it would take forever ..For that matter you could use a gasket delete and gain maybe 16-18 thou .That gasket is around 20 thou .

 

[Mastermind]

Thanks you sir...
Thanks all of you,, yer the best.
Found a oem jug and its on its way.
Will check in later.

If the plating is good, I'd be willing to cut the base and squish for you.....but I doubt it would be a great performer even with more compression. Getting the exhaust as low as possible is my objective on the 066. The intake is a problem as well. I'd hang onto it as a "what not to do" conversation piece.

 

[jacob j.]

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There were a couple of guys local to me that were setting up their intake ports like that (I call it the Mickey Mouse style).

They stopped doing it when they found out it was actually making the saws slower than stock in the cut.