Ronie
Here For The Long Haul!
I read a paper by a Japanese engineer on porting and in a study he did he said there was a much greater chance of the second ring catching the port when the port is widened.
Post up your ported cylinder Artwork
- Thread starter Chris Zautner
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Ronie
Here For The Long Haul!
That makes sense. I couldn't remember the reason but that second ring catching stuck in my head.
Ronie
Here For The Long Haul!
I just did a search trying to find that paper and all I could find is a part of it.
Nakashima, Kohei & Fuma, Kazuki & Kurokawa, Daisuke & Nakano, Yuki & Murakami, Yoshio & Yamamoto, Masago. (2012). Piston Ring Projection and Catching in Cylinder Ports of Two-Stroke Cycle Engine. Journal of Advanced Mechanical Design, Systems, and Manufacturing. 6. 23-32. 10.1299/jamdsm.6.23. In a two-stroke cycle engine, the piston and its piston rings slide over the cylinder wall and its cylinder ports. This study investigates how those piston rings project and catch in cylinder ports, and examines the effects of engine speed and round chamfered ports on projection and catching. Strain gauges were installed on the bottom of the top and second rings, over the intake and exhaust ports. The variation of strain was then observed over each engine cycle. The piston behavior was then analyzed to consider ring projection and catching in ports. Results suggest the rings indeed project and catch in the ports, immediately after the piston moves from the intake port side to the exhaust port side, and again when the piston continues moving along the exhaust port on the upward stroke. Engine speed had a minimal effect on this projection and catching. However, larger round chamfered ports might decrease the second ring projection and catching in the exhaust port.
Deets066
AKA Deetsey
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You want the most outward pressure you can get with the rings. This makes for better ring seal and compression. Also makes it easier to catch in a port with inadequate bevel or too great of a width without enough arch
Lightning Performance
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The paper states nothing about the arch or the ring locating pin as Deets stated in his prior post. It is irrelevant imo without that information included in the "test."
Robert Krogh
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Damn....welp....nothing wrong with that polish job lol....
Thats so nice looking I wouldn't mount it on a saw!
Thats so nice looking I wouldn't mount it on a saw!
Coffee table only
Gorgeous work. It’s some of the cleanest I’ve seen.
Maintenance Chief
Disrupting the peace with an old chainsaw
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You know you're weird when you set up a display of cylinders in your house, lol.
qurotro
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When CAD ain't weird enough.
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ok, i'm not gonna ask HOW u did such a nice job.... just gonna ask HOW LONG it took you to do all that? thats about 2 hours of grinding with no mistakes AND then about another 6 of polishing I'd guess. jeez ... showed it to my wife and even she thought it was pretty.
Robert Krogh
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Well, I can honestly say that I don't know. I only port saws for my personal use and thus far I've never ported the same model twice. It's a hobby for me that I really do out of necessity. I heat my house with wood and do all my cutting on national forrest between 7500' and 10,000'. I can tell you that a stock saw at that altitude runs exactly like crap. I found myself buying bigger and bigger saws all the way to a 395xp and was still never satisfied. I never intended to take this up, in fact I payed a professional builder to port a 372 for me with a 51.4mm top end. We discussed the environment I cut in and what I was trying to accomplish in detail. The saw ran pretty well but I was disappointed with the lack of craftsmanship. I ran a compression test and that led me to pull the cylinder, what I found was unacceptable to me. I began to study 2 stroke theory and found you but of nut jobs who have scattered enough information around to allow me to start building my own saws, thank you all for that as far as time goes it's of no consequence to me. I will say that I probably spend more time planning out how I want the cylinder to come out than I actually spend grind/finishing. I try know exactly how and what I'm going to do before I ever put a cutter in a cylinder. 20 years ago I spent alot of time porting and flow bench testing cylinder heads so these little ports made of aluminum really require small amounts of material removal comparatively speaking.
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Well....
You do beautiful work.
I guess you must take a lot out of the squish band to set static compression comparable to sea level builds.
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@Robert Krogh
Boy did you hit the nail on the head man. Too many professionals aren't professional.... as a general rule. Finding the guys that really take pride in what they do is quite the task.
One thing to consider is that the polishing doesn't necessarily lead to a super running saw....but if a saw runs like crap and you see a carefully done head....you are gonna be much more likely to give the builder leeway because they really put the hours in. Its the saws that run like crap that look like crap internally that cause all the fuss lol.
I cant match what you do. ( ...and i grind on teeth for a living lol.) Congrats on setting the bar higher for pros and diyers alike
Boy did you hit the nail on the head man. Too many professionals aren't professional.... as a general rule. Finding the guys that really take pride in what they do is quite the task.
One thing to consider is that the polishing doesn't necessarily lead to a super running saw....but if a saw runs like crap and you see a carefully done head....you are gonna be much more likely to give the builder leeway because they really put the hours in. Its the saws that run like crap that look like crap internally that cause all the fuss lol.
I cant match what you do. ( ...and i grind on teeth for a living lol.) Congrats on setting the bar higher for pros and diyers alike
