Reed Valve Design Ideas Poll

Nice work Roddie!


I've played around with various reed designs over the years. I like the Mylar star reeds the best.

One reed design I think could be a winner is this:



These were designed off a reed I hand cut out of a floppy disk one day. Jason made the first machine-cut ones off the design. I need to get a new cutting mat for my die-cut machine, then I can get back to cutting them out. I know a few of you guys on here are probably waiting for them. They need to be ran through a lot of tests to see if they really improve anything first. I know I sent some to a few members on here...have never heard anything back about performance though.

Roddie I like the star shape but to me the "hybrid" leaves too small transfer area i.e. only 2 small bites through which the mixture is drawn into the crankcase...of course your bench test will tell us if I am wrong

Roddie,
Great creativity and engineering to make a complicated shape easy for even me to do !!!!
Thanks, Steve

My gaskets finally came from Cox Int. today. Now I can resume testing.

I've been thinking of getting some of those Cox Forum reeds to try.

by balogh on Mon Mar 26, 2018 2:27 pm

Roddie I like the star shape but to me the "hybrid" leaves too small transfer area i.e. only 2 small bites through which the mixture is drawn into the crankcase...of course your bench test will tell us if I am wrong

You're probably correct Andras.. but we'll see. I'm hoping to possibly improve fuel-economy without sacrificing performance. Who knows how much (if any) unburnt fuel passes through the exhaust ports. It certainly happens with a rich needle-setting.

by 66 Malibu on Mon Mar 26, 2018 5:40 pm

Roddie,
Great creativity and engineering to make a complicated shape easy for even me to do !!!!
Thanks, Steve

I actually enjoy messing around with these kinds of things Steve. I'll probably end up in the funny-farm from it one day though..  

A circle-template is a must-have tool. I use it for lots of things. It definitely came in handy for this application. I used the 7/16" and 7/32" to mark the reed's outer-diameter and seat-area respectively. This helps to provide a ball-park reference when punching the radii for the star-shape.

The oblong/oval-shape reed is easy to make.. once you get the hang of it. The "straight-sides" are approximately .270" apart. If you cut a strip of material to that width.. and a couple of inches long; you've then established the cross-section for cutting as many reeds as will fit on the strip.. side-by-side. I use a small steel-rule and razor-knife. The 7/16" circle-template is used to mark the radii by placing it over the strip and sighting-it on-center. Mark the radii with a fine-point pen. Using a "nibbling-action" with good sharp scissors; cut the radii "on".. or just inside the ink-mark.

You'll know where to cut after making a couple. If the overall radius is too "large".. the reed will warp in the housing.. and won't seat properly. Too "small".. will allow side-movement of the reed which would probably cause "floating" and loss of power. In extreme cases.. a reed that is much too small could slip past the retainer.. and get sucked into the crankcase.

I made a couple more reeds this morning.. marking the seat-area..




Note a new experimental cross-flow reed-type having x4 radii of .125" accomplished using my 1/8" hole-punch.




Again; this material is a semi-rigid type of plastic-sheet which is "gloss-smooth" on one side and has a "matte-finish" on the other side. The thickness is .008". The smooth/reflective side faces the valve-seat.. and the matte-side I use to make my ink-marks.