Stihl 066 wise me up, Part II

[Trigger-Time]

I'm having squish problems, I put a new crank in a 066
I wanted to make sure the bottom end was good before
spending money on the top end. I had a new set of rings
on hand, used the old piston with new rings, piston skirt
is worn shinny..........Saw run good but had a noise at idel.

Bought OEM piston, pulled cyl. off saw today
I thought it was the worn piston slapping the sides
of the cyl,............... piston slapping the top of cylinder
Every thing is OEM, gasket is 0.5mm
New piston has EB on top ? (not installed yet)
To much flash to get a good pic of cylinder.

So are the cylinders not interchangeable......I don't see how I could
have caused this



Part I, http://www.arboristsite.com/showthread.php?t=47180

 

[Lakeside53]

Any chance someone decked your cylinder?

I assume your crank big end is fine...

JacobJ says he's seen cases that were machined wrong, but I never have. I have seen a few cylinders that were messed with though.

EB - yes, seem that on the later shipment of pistions also, but that's not the issue - just bore fit.


Measure you squish.. at 4 or 8 points simultaneously ( take the rings out - it's easier) - looks to me that you are hitting on one edge only??

 

[Trigger-Time]

The cylinder that is hitting is .006 shorter (from deck to where its hitting the hardest)
than the cylinder I want to use with new piston.......It is also
the cylinder that was on the saw before the new crank.

 

[Trigger-Time]

Any chance someone decked your cylinder? I don't think so
I assume your crank big end is fine...Its new, no play

JacobJ says he's seen cases that were machined wrong, but I never have. I have seen a few cylinders that were messed with though. Cylinder has a very small shoulder......it left a step in top of piston
EB - yes, seem that on the later shipment of pistions also, but that's not the issue - just bore fit.


Measure you squish.. at 4 or 8 points simultaneously ( take the rings out - it's easier) - looks to me that you are hitting on one edge only?? Yes edge only

Blue is me

 

[Lakeside53]

If 6 thou is the issue... it's way too tight squish.. 18-20 is where I like to see them and typical of factory (that Ive seen and measured).

Are you using the OEM steel gasket, or paper?

Were you hitting on ONE SIDE of the piston or all around?

 

[Lakeside53]

Blue is me

I'd laugh, but...

to hell with it..

sorry...

 

[Trigger-Time]

If 6 thou is the issue... it's way too tight squish.. 18-20 is where I like to see them and typical of factory (that Ive seen and measured).

Are you using the OEM steel gasket, or paper?

Were you hitting on ONE SIDE of the piston or all around?

OME steel gasket

Yes, one side only

 

[Trigger-Time]

I'd laugh, but...

to hell with it..

sorry...

 

[stihlatit]

If I am not mistaken there is a thicker gasket is there not. If I am wrong about that or if that is still not enough clearance would two steel gaskets work Lakeside?

 

[Lakeside53]

OME steel gasket

Yes, one side only

One side only is bore wear, or, if you are really tight with squish, the normal rocking of the piston (a few thou on a new piston) Something is way to tight...

What did the old piston look like?

 

[Trigger-Time]

One side only is bore wear, or, if you are really tight with squish, the normal rocking of the piston (a few thou on a new piston) Something is way to tight...

What did the old piston look like?

This is the old piston........Have not tried the new one.

 

[Trigger-Time]

Repaced crank, used old piston w/new rings
used cylinder from other dead 066, piston was hitting
top of cylinder

Bought new piston, going to use cylinder that came off
this saw (not the one that is hitting cylinder)

Want to use this as milling saw..........if the 1.0mm gasket
is not a BIG power loss........I will do that

 

[Lakeside53]

Ah... hmmm... your original post confised me with thre talk of new piston. Put in the new piston, no rings, and measure the squish. I bet it's fine.

The slap is NOT side to side, but front to back!

The head slapping is then MOST likely just your OLD piston with taper... I've had 026's pound the cylinder head above the exhaust port when the piston wears. Yours is minor.. so far.

 

[Trigger-Time]

Old piston is 2.110 @ bottom of skirt
New Piston is 2.124 @ bottom of skirt

I would think .014 diff is a bunch........and my problem, yes...no....maybe?

We where posting........same time

 

[Trigger-Time]

Ah... Put in the new piston, no rings, and measure the squish.

The head slapping is then MOST likely just your piston with taper... I've had 026's pound the cylinder head when the piston wears.

Don't have the stuff to check squish need to go to town.

Second thought...........I think you are right, New piston is going IN!
Lake how many beers for ME, to get it done..........Start the clock!

 

[Lakeside53]

Soft solder and a micrometer or even digital calipers? heck, you have the nice starett depth gauge (same as mine !

I'd just put in the new piston and run it..

 

[Lakeside53]

Old piston is 2.110 @ bottom of skirt
New Piston is 2.124 @ bottom of skirt

I would think .014 diff is a bunch........and my problem, yes...no....maybe?

We where posting........same time

yes.... and obviously you DO have the tool to measure squish use your old gasket for the measurements, then put in a new gasket for the final assembly of the new piston. I'd just put it togther with the new piston and run it

 

[Trigger-Time]

Stop the clock........

New piston is in......NO piston slapping noise :rockn: :rockn:

Damn circle clip.......also drilled the muffler baffle

PLAY TIME!

Lake, Thanks
ME BLUE NO MORE!

 

[Trigger-Time]

yes.... and obviously you DO have the tool to measure squish use your old gasket for the measurements, then put in a new gasket for the final assembly of the new piston. I'd just put it togther with the new piston and run it

The only solder I have is some big dia stuff.

 

[Jacob J.]

So you re-used the steel gasket and it's doing fine?