Metals406
Granfodder Runningsaw
I wouldn't take that laying down! Time for a strongly worded letter to the store manager!!Am going through cheese withdrawls ,the store is out of tillamook and string right now
I wouldn't take that laying down! Time for a strongly worded letter to the store manager!!Am going through cheese withdrawls ,the store is out of tillamook and string right now
Yes I understand that - then again if you go back to the first page of this thread it was really about both domed pistons and popups. The two are minor variations of the same thing, differing only in how steep the edge of the lump is. Other recent discussion has been about how transfer flow patterns are disturbed by the presence of a disruption on the piston face, and also included domed pistons. I included the comment about Zenoah engines to point out that this is not really a settled topic, and that some rather capable engine designers are still not using flat pistons.You are confused Chris.
A popup is not a dome.
This is a popup......note the obstruction on the crown?
View attachment 394913
Yes the 543XP has a domed piston, I just ported one. I still cut the squish band. It was far more complicated than a flat squish band......
I agree Shawn.
I also like the added control I have over the port timing.
For instance, on a lot of saws, I can lower the exhaust. I can make some of the older saws (think 262XP and friends) run like they would never run with a popup because of that.
You are confused Chris.
A popup is not a dome.
This is a popup......note the obstruction on the crown?
View attachment 394913
Yes the 543XP has a domed piston, I just ported one. I still cut the squish band. It was far more complicated than a flat squish band......
So.....aside from the whole popup thing.....
What about windowed pistons, and their effect on case compression?
And these days all the cool kids are discussing intake height. How does that enter into this conversation?
I like case compression... But when to say when??? How much is too much?
Agreed... But would you say anything over 158-160 intake duration is excessive and will turn your saw into a fuel swilling, slow excellerating, pig? Or would it have more to do with the relationship between case volume/transfer length/ and overall crossectional area of your upper transfers??Depends on the application Matt.
In a high RPM saw.......I would want much less than in a working saw.
You should have bought an arctic cat...Matters what altitude you're at. Chew on that.
I know a couple guys been doing that for years...Your intake opening has an effect on your effective crankcase compression. Hence why someone would fill in the bottom of an intake port.
Agreed... But would you say anything over 158-160 intake duration is excessive and will turn your saw into a fuel swilling, slow excellerating, pig? Or would it have more to do with the relationship between case volume/transfer length/ and overall crossectional area of your upper transfers??
I haven't even cut the plastic off yet...I don't think there are any "always" situations.
The MS660 doesn't seem to mind intake durations in the 170* range at all.
Some other saws don't work well at all in those ranges. So........I don't really know.
I've still got so much to learn too. I feel like I'm just now getting a decent scratch in the surface.....
You should have bought an arctic cat...
I told you those polaris' were bad juju..
I don't think there are any "always" situations.
The MS660 doesn't seem to mind intake durations in the 170* range at all.
Some other saws don't work well at all in those ranges. So........I don't really know.
I've still got so much to learn too. I feel like I'm just now getting a decent scratch in the surface.....
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