Inside the "Triple Nickel"

[wigglesworth]

Pop-up piston wash....



What I like to call near perfect piston wash...



Anybody see what I see?

 

[wigglesworth]

doesn't the 026 have a dome piston? didn't some of the old mag saws come with dome pistons? there has been quite a few saws from the factory with a dome and some with a dish piston.

A dome and a pop-up are two entirely different things.

 

[Red97]

let's put it into perspective, he wont let the pizza guy come thru the gate.

I'm 98% sure a ball/stick or rope getting tossed will divert his attention, Pretty familier with those "type" of dog. LOL Unless trained otherwise.


hijack over Now where's the finished video?

 

[wigglesworth]

just how many 2 stroke boat motors out there have huge dome pistons,how many different brands of dome pistons are out there for hot rod drag cars . theres nothing wrong with a dome piston. theres been an awful lot of domed piston work saws built in the last decade and now all the sudden its not good enough.

Again, we're talking saws. Air cooled, small cc two strokes.

No manufacture that I know of has ever put a pop-up piston in a saw from the factory except the 028 super.

I'm not saying it won't build compression, or even run forever. But what I am saying is I think there is a better way...

 

[Red97]

Again, we're talking saws. Air cooled, small cc two strokes.

No manufacture that I know of has ever put a pop-up piston in a saw from the factory except the 028 super.

I'm not saying it won't build compression, or even run forever. But what I am saying is I think there is a better way...

I agree. A tighter quench will make more power than a pop up. Now If you match a dome exactly to the combustion chamber than you can get best of both worlds, tight quench and good flame travel.

 

[Mastermind]

Flattening the squish band to achieve higher squish velocity stops detonation. A popup interferes with that.

You guys can go back and forth all day.......but I know my way is better.

Because I say so.

 

[Andyshine77]

I'm all about accheiving a higher compression ratio, without hindering flow across the piston crown. A popup will hinder flow. I've seen it with my own two eyes. Heavy carbon buildup, uneven piston wash and even detonation.

How many saws came factory with a pop-up piston? Only one that I'm aware of, the 028 super.

Nobody ever wonders why?

That's not really correct. Many older saws had variations in piston design, Remington even had a piston that directed flow with a huge lump on top of the piston. With that said I completely agree with you. How much will it effect performance? likely very little IMHO. I still don't care for them, especially in a true work saw.

 

[wigglesworth]

That's not really correct. Many older saws had variations in piston design, Remington even had a piston that directed flow with a huge lump on top of the piston. With that said I completely agree with you. How much will it effect performance? likely very little IMHO. I still don't care for them, especially in a true work saw.

Maybe I should had said in the last half century. Haha

 

[Andyshine77]

Maybe I should had said in the last half century. Haha

Every manufacture has it's own philosophy, the same thing can be said for us saw hacks.

 

[bryanr2]

Im just glad all of you guys are getting along. Even if you all see things differently, your willingness to share, debate, and discuss this stuff benefits every one on the forum. Competitiveness is good for the Consumer/Us.

 

[Jim Timber]

That's not really correct. Many older saws had variations in piston design, Remington even had a piston that directed flow with a huge lump on top of the piston. With that said I completely agree with you. How much will it effect performance? likely very little IMHO. I still don't care for them, especially in a true work saw.

How many rev'd to 14K?

Mainly just wanted to sub to this one, but that's a big difference between the days of draftsmen using pencils and modern SolidWorks with flow modeling so pervasive in the engineering departments now. If they completely dropped the dome/pop up from the designs, there's probably a reason. If Husky or Stihl, or whoever, could bump the power of a saw with a piston swap alone, wouldn't they be doing it? Programming the machine to cut the piston face with a step or dome wouldn't change anything on the cost of manufacturing end of things. It's not like they need to add valve reliefs.

 

[Mastermind]

We've kicked this around many times over the years, and it's a great discussion. But it can get out of hand. I'm all for a little friendly ribbing.....but no fussing please.

I'm really enjoying the way this place is at the moment. The level of sharing that is going on behind the scenes is wonderful.....and can only result in better saws being built for the end user.

To hell with rivalry.

I remember a few years back when EC was cutting squish bands, and I was still doing popups. In my mind I was convinced that compression was compression......that the shape of the piston crown didn't really matter, as long as compression was raised.

I was wrong. Eric was spot on.

I had to do a bunch of squish band mods VS popups before I was convinced though.

Will you notice the different in a worksaw? Most users will not. Chain makes far more difference than the shape of the piston crown......and most guys struggle to file a good chain. The piston crown becomes a mute point pretty damn fast in their hands.

The pictures Jeremy posted of the piston crowns are very telling. It's plain to see that the popup becomes an obstruction to the incoming side fed transfer flow. If we were introducing the charge from above (like a OHV engine) then the popup would not be so much of an issue.....but we are not discussing an OHV engine here.

The last thing I want is to start up any old fussing or feuding......so I'll just leave you guys with one last thought.

My way is best.......and you all know it. So there.

 

[MrGiggles]

Any idea if the 555/562 jug will fit on a 545/550?

 

[sunfish]

Any idea if the 555/562 jug will fit on a 545/550?

No, not a bolt on, but I know a guy that could probably do it...

 

[blsnelling]

The strokes are different. Wouldn't work.

 

[bryanr2]

We've kicked this around many times over the years, and it's a great discussion. But it can get out of hand. I'm all for a little friendly ribbing.....but no fussing please.

I'm really enjoying the way this place is at the moment. The level of sharing that is going on behind the scenes is wonderful.....and can only result in better saws being built for the end user.

To hell with rivalry.

I remember a few years back when EC was cutting squish bands, and I was still doing popups. In my mind I was convinced that compression was compression......that the shape of the piston crown didn't really matter, as long as compression was raised.

I was wrong. Eric was spot on.

I had to do a bunch of squish band mods VS popups before I was convinced though.

Will you notice the different in a worksaw? Most users will not. Chain makes far more difference than the shape of the piston crown......and most guys struggle to file a good chain. The piston crown becomes a mute point pretty damn fast in their hands.

The pictures Jeremy posted of the piston crowns are very telling. It's plain to see that the popup becomes an obstruction to the incoming side fed transfer flow. If we were introducing the charge from above (like a OHV engine) then the popup would not be so much of an issue.....but we are not discussing an OHV engine here.

The last thing I want is to start up any old fussing or feuding......so I'll just leave you guys with one last thought.

My way is best.......and you all know it. So there.

That there holds alot of truth! I went with Mastermind years ago bc I read in total silence on the site for a year before picking a builder. I enjoyed his threads, and the fact that he is so approachable. I said many years ago, that if a builder wont share his knowledge, I wont share my money... it's too hard to come by. Randy has continued to share his work and it hasnt hurt him doing so in any way. I have read every single thread he has ever done and I still have no interest in porting my own saws. He's completing number 26 and 27 this week. (may already be done). Point is, work together guys, share your knowledge, have discussions publicly and privately. There is no shortage of work, no need for egos or disputes. Your client list is constantly growing, and you never know who is reading in silence, evaluating, and choosing who they want to use. I am sure when I took that beater clamshell Echo cs520 to Randy Dec 2010 (after 47 shared emails) that Randy didnt think nothing of it. 27 saws later, he is my dearest friend, and he has a client for life.

 

[Mastermind]

I still want a 520 of my own BTW.

 

[Fire8]

I still want a 520 of my own BTW.

 

[DeckSetter]

So if it leans out and toasts a piston but the cylinder can be reused, how close to the same squish do you usually come with a new piston? Does it ever become a problem of having the squish too tight after the band has been cut and if so what do you do then? Trying to learn.

 

[Mastermind]

A replacement piston fits without any drama.