Windowed piston in an open port cylinder ?

[David Young]

completely stock, then I put it away. I think it could be optimized with some porting but it was running pretty good. The intake and exhaust are limited stock

 

[Magic_Man]

With the factory full circle piston I was able to add considerable width on my 51 with a 45mm bore. I went 65% of bore which is 1.15 inches. From what I can remember the factory intake was in the .8 range and the exhaust in the .9 range. I will have to get the 028s piston here and see if skirt width and ring placement will allow those widths.

 

[Al Smith]

I stopped being concerned about what anyone thought not only how I did saw engines but every walk of my life.Not recently either,years and years ago .

I figure it's your saw do it to suit yourself .If it works good .If it doesn't you learned something .

"arm chair" quarter backs are just talk,BS artists .If you play the game then play it well .Doers win,talkers talk .

 

[Magic_Man]

I stopped being concerned about what anyone thought not only how I did saw engines but every walk of my life.Not recently either,years and years ago .

I figure it's your saw do it to suit yourself .If it works good .If it doesn't you learned something .

"arm chair" quarter backs are just talk,BS artists .If you play the game then play it well .Doers win,talkers talk .

Wise words Al, I have always walked a different path than most in life. While this conversation has turned to building a husky with a 028s piston, which was my thinking when I started it, was not solely the reason. I was and am more interested in learning about different combinations and how they act in general. I'm still green and was looking for a little knowledge before reverting to my usual " Hold my beer and watch this" self.

 

[Al Smith]

You never know if you never try .

 

[Zombiechopper]

200T has a windowed piston and open transfers. They run pretty good like that. The theory goes over my head, so you guys carry on without me. Just wanted to point out a stock setup that runs quite well.

 

[GoBigBlue1984]

I've built 2 46mm open port 55's using windowed Pistons. Sold one, the guy loves it. I've got the other hanging up. I'll post some pics of the spacers that I wired off the bottom of bad jugs to use with the 028 piston.

 

[GoBigBlue1984]

I used a windowed piston in the first 55 a few months back and it was snappy, I couldn't tell much difference but I sent David a video of it running and I recall him saying he felt as though it needed more transfers. Correct me if I'm wrong here David.

 

[Czed]

@Termitebuffet
Here's some info

 

[JCalef]

I'm getting 275 pounds of compression with my 028 piston in a hy way jug. I had .024 of squish. I doubled up the base gaskets. I also doubled up the washer on the spark plug.

 

[Al Smith]

275 is in diesel comp range .

 

[Ford3000]

275 is in diesel comp range .

Would be interesting to run a tank of diesel through it, @ 40:1 of course.

 

[Al Smith]

Somebody made a diesel chainsaw .I'll bet that would rattle the teeth right out of your head .

 

[smokey7]

I'm getting 275 pounds of compression with my 028 piston in a hy way jug. I had .024 of squish. I doubled up the base gaskets. I also doubled up the washer on the spark plug.

I would knock the dome off that one to bring it closer to 225. Idealy 180 to 200 i find runs best.

 

[Maintenance Chief]

I have a 55 I'm working on now , the factory quish is about .038 without the base gasket.
The 028 piston has a .041 rise from the top (AM piston) .
I'll have to take .015 from each side of the pin bore for the 028 piston to fit on the rod.

 

[Maintenance Chief]

I think that's I the realm of possibilities I think mine was 240 after a few cuts. I should dig that project out and continue some testing.

Cool ,make video.

 

[82f100swb]

I have one set up with the Hyway closed port jug(which is a bit of a joke, they just closed in the open ports, didn't actually change the cylinder design any) and it makes just shy of 245 last I had a guage on it. With the supplied piston the Hyway top end had .060ish squish with no base gasket, in an OEM open port jug it was at .020.
I am running a .010 base gasket with the 028S piston, which put me right at .0205.
I mean, the thing runs decent compared to what I started with with this top end, but I ran a 254 long before I touched a 55 so, I've never been hugely impressed by a 55. This one never fails to disappoint
Here it is running a 3/8 20" setup:

February 11, 2023

youtu.be

And .325 with an 8 pin, in some frozen wood that it really didn't like:

February 11, 2023

youtu.be

Some smaller birch it din't mind too much:

February 11, 2023

youtu.be

And my stock 254. Same bar/chain setup every time:

February 11, 2023

youtu.be

February 11, 2023

youtube.com

My next venture with a 55 is going to involve a non Husky jug....

 

[5155]

This is the time I wish for a gauge, only to compare mine with what you guys are doing.
1 cp 55 at 22 squish is a pain to start in working environments.
And does not run any better than another cp at 33 squish that I think is just right.
I think carbs matter though,
I think I like the walbro better than the zama.
Could change my mind on that as parts get swapped around.

 

[82f100swb]

I am actually running a HDA 120 off of a 262 on the 55 above, I definitely did not like how it ran with the Zama.

 

[5155]

That's interesting to know about the 262 carb working for the 55.

Was told on here one of my 55s has a non husky top but did not research that.
That one has the fresh walbro, maybe tomorrow take it for a spin.
These saws been serviced so many times in their life they don't know, and I don't care their names. Just so they perform.
We finally get some nice weekend weather and I sleep all day lol.