Anyone want to help a greenhorn porter with some numbers? Stihl 661

[timbertramp]

let me preface this by my saying, I know very little about the art of a good hop BUT I’m learning...
I’ve been lurking and watch some videos but I’ve been wanting to spin up a 661 a bit.
So I measured this up and this is what I came up with (I may have done a bad job this is where the help comes in)
Stihl 661
Ex 102*
In 82*
Trans 125* respectively that’s the front of the ex side
Decked the cylinder for .023 squish

So I’m wondering about those numbers... also how many are raising the transfer roof so they are even? Gains?

So anything is welcome...this will be a mtronic limited, it’ll get filter upgrades and I triple port the exhausts, that’s been working good. I’m trying to learn and Looking for torque and flow...bigger rpm’s is what I call it...these are working saws, I just want torque on the stump for 36” bars mostly...running these saws at 6,000 ft typically

 

[Lightning Performance]

Welcome
I'll give you one tip. Find the port choke and open it up. Always a gain there.

Almost forgot those numbers. 1, 2, 3... numbers ain't everything.

 

[Stump Shot]

Welcome to the forum

I would kindly suggest adding "Stihl 661" somewhere in the title so folks with experience with them, can see it and possibly chime in to help.

 

[timbertramp]

I’m not afraid to ask dumb questions...

 

[Moparmyway]

You can clean up the exhaust and raise it to 100
Dont touch the transferrs
Widen the intake to 0.030 from the skirt edges and leave it at 82

Did you clean up the squish band ?

 

[Stump Shot]

I’m not afraid to ask dumb questions...

Only "dumb" question, is the one not asked.

 

[timbertramp]

Did you clean up the squish band ?

It’s pretty consistent across but no I haven’t touched the head....I need to get a mandrel made...I just been running them.
Now I’m making an educated guess at precisely what your asking but I think I’m right.

 

[Moparmyway]

A mandrel will allow you to cut the base.
Once you cut enough of the base off, or if you want to change the combustion chamber, you will need to cut the squish, with a lathe preferably.

Here is a 661 cylinder in a lathe on a mandrel to cut the base true


Some people use a mandrel to cut the squish, so long as you dont dig into the plating of the bore, that can work too

 

[timbertramp]

A mandrel will allow you to cut the base.
Once you cut enough of the base off, or if you want to change the combustion chamber, you will need to cut the squish, with a lathe preferably.

Here is a 661 cylinder in a lathe on a mandrel to cut the base true
View attachment 121822

Some people use a mandrel to cut the squish, so long as you dont dig into the plating of the bore, that can work too

I thought using a mandrel to cut the squish by hand. I really like that process for what I have to work with. That’s what I was hoping to build... I’m just running the stock band right now at .023....I hit it with a flex hone just to polish it up a bit...