Check out my squish!

[Matt_M]

First time measuring squish on my husky 350.
Using an aftermarket P&C. Measured 1mm all around.
Still have the base gasket.

Before
View attachment 299785

After
View attachment 299786

What do ya reckon? Look like I did it right ?

Just gotta do a vac and pressure test then reassemble and try my hand at tuning. Got a new TTO tach to try out.

Matt

 

[blsnelling]

.040" is WAY too much. Loose the gasket and measure it again.

 

[z71mike]

I got an 026 a/m kit cut down to .012 and it still is only blowing 150psi with no balls. I got a bad kit. Last time I buy from my local shop.

 

[blsnelling]

You're only running .012" squish?

 

[KenJax Tree]

On my 346's i ended up with .020 on one and .019 on the other.

 

[Matt_M]

Ok I'll pull the bottom gasket out. What type of sealer should I use in its place ? Any gasket paste or are there ones we should steer clear of ?

 

[old-cat]

I'm fixing to do my MS260 at .010" squish, maybe a couple more thou. I've got my 034 Super at .015" and I work that thing HARD!

 

[blsnelling]

I'm not going to say that I've never seen a saw that tight, but I'd sure be careful. It wasn't a saw that I built, but showed no signs of issues. If it's not hitting, then watch for pitting in the crown.

 

[cutforfun]

I'm fixing to do my MS260 at .010" squish, maybe a couple more thou. I've got my 034 Super at .015" and I work that thing HARD!

You are asking for trouble

 

[bucknfeller]

Ok I'll pull the bottom gasket out. What type of sealer should I use in its place ? Any gasket paste or are there ones we should steer clear of ?

Has to be resistant to gasoline. Threebond 1194 is commonly available around here. Yamabond 4, and Hondabond are the same stuff, Loctite 518 works good too. Dirko is what Stihl recommends, and your dealer can order it for you if they don't stock it.

 

[blsnelling]

detonation can do nasty things to piston crowns.

I'm not saying it will, but to keep an eye on it.

 

[old-cat]

You are asking for trouble

Not "trouble", experience.

 

[z71mike]

You're only running .012" squish?

Yup. Not on purpose. With .016 I was still only at 130psi with Cabers.

Thought about adding a gasket to bring it back up, then go from there I guess. Not sure really.

 

[z71mike]

compression is pretty low, detonation shouldn't be a problem....as long as the hard parts to hit....:confused2:

Yeah i kinda hit a wall when the compression numbers were coming out so low. Strange.

At first bolt-up with a gasket, uncut, it was down around 100psi. First words: "Oh no"

 

[z71mike]

I have thoroughly trashed wild thing that pumps more than that, and it won't even pop. Are you sure your gage is relatively accurate?

Good question. With the lackluster performance of the saw, I assumed my gauge wasn't on the fritz. But it's worth a check anyway.

 

[nmurph]

The problems with squishes below .014-.015" is are that -

the piston and cylinder expand and grow as they heat up and physically hit each other as the piston rocks in the bore.

the fuel charge is squeezed out of the squish area where it acts as a coolant to the piston crown.


Matt, you need to reorient your solder by 45°. Two pieces should be along the axis of the wrist pin and the other two should be at the exhaust and intake ports.

 

[old-cat]

The problems with squishes below .014-.015" is are that -

the piston and cylinder expand and grow as they heat up and physically hit each other as the piston rocks in the bore.

the fuel charge is squeezed out of the squish area where it acts as a coolant to the piston crown.

Another member here said he has a Husky with .010" squish that he has been running for years. Could that be mis-measurement? Or bs?

 

[nmurph]

Another member here said he has a Husky with .010" squish that he has been running for years. Could that be mis-measurement? Or bs?

Yes.

 

[old-cat]

nmurph

I'm going to take your advice and go with .015" minimum. My 034 Super sure runs good that way, and that is NOT mis-measurement or bs either!

 

[nmurph]

I prefer to stay on the otherside of .017". I know you can go a little tighter, .015" is OK on a 50-60cc saw if it is tuned correctly and the mix is good, but I shoot for .018-.022" on my 346 rebuilds.