Mysterious Stihl 064

[Lightning Performance]

@Sunterbach

It seems like you have several things working against your rebuild like Kevin^ said.

Make sure you open the throttle plate on a larger cylinder or any cylinder during a compression test. Adding oil into the cylinder to do a second test can shed some light on the ring sealing abilities. The ring end gap being under 0.030 shouldn't be an issue. Having the wrong rings fluttering about in a ring land is an issue so double check the right ring height is being used. Your low numbers sound almost like ring damage or a broken one up top. They should have nice smooth even faces with some slight machine marks or ribs from moly face coatings most times.

 

[cookies]

makes me wonder if he has 1.2 mm think rings in a 1.5mm ring land

 

[Sunterbach]

Hi everybody. Long time no talk. I decided to pull the 064 back off the shelf to give it another shop. I got my 395 ported by a guy outta Pioneer, CA (@leave_nothing_stock on IG, if you’re in the area he does amazing work) so that reinspired me.
Anyway. Here’s what I have (on top of the full bottom end rebuild). I have the OEM cylinder, the new Meteor cylinder, new Meteor piston, new OEM rings and new Caber Rings.

For ring gap im getting:

Old OEM jug
OEM rings: .017in
Caber rings: .26+in (biggest feeler gauge I have)

New Meteor jug
OEM rings: .12in
Caber rings: .23in

So I’m not happy with that.

As far as squish with new Meteor piston:

OEM jug w/ gasket: .032in + (that’s how big my solder is)
OEM w/o gasket: did not test

Meteor jug w/ gasket: .032in+
Meteor w/o gasket: .16in

95-105psi compression across the board.

The most confusing thing to me is the right squish with **** compression anyway.

Anyone got some fresh thoughts for me???

 

[Sunterbach]

makes me wonder if he has 1.2 mm think rings in a 1.5mm ring land

I will check this when I get home!

 

[cookies]

I will check this when I get home!

Also try plugging the decomp hole and retesting

 

[Bob Hedgecutter]

There are some omitted 0's in the numbers above eh?

Ring end gap- how far into the cylinder are the rings being placed to take your readings and are they dead square to the bore?
You know you can place two feeler gauge leaves together to add up to bigger than your biggest single leaf?

Squish- what base gasket ae you using? The 1mm or the 0.5mm one? New or old gasket? Cylinder sitting tightish down on the gasket or cranked down as it would be on a finished build?

Compression- is the gauge a proper small engine gauge? Do you have another running saw (your wizzbang ported 395 for instance) what does the same gauge show for that saw?

 

[Sunterbach]

There are some omitted 0's in the numbers above eh?

Ring end gap- how far into the cylinder are the rings being placed to take your readings and are they dead square to the bore?
You know you can place two feeler gauge leaves together to add up to bigger than your biggest single leaf?

Squish- what base gasket ae you using? The 1mm or the 0.5mm one? New or old gasket? Cylinder sitting tightish down on the gasket or cranked down as it would be on a finished build?

Compression- is the gauge a proper small engine gauge? Do you have another running saw (your wizzbang ported 395 for instance) what does the same gauge show for that saw?

-yep whoops forgot some zeros.
-I’m only putting them in just below (above when the cylinder is upside down) the transfers. I also pushed them into the other side of the transfers and the numbers didn’t change.
-oh. Duh. I didn’t think about two feeler gauges. Shows what kinda hack I am
-.5mm gasket. Tightened down like finished work. New gasket
-I have 2 compression testers. They put out the same numbers on all saws. I’m able to pull 150+ on my other saws that run right. I’ll check the 395 tonight I’m curious.