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Old-Style Star Reeds

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Old-Style Star Reeds

Post  Sig Skyray on Wed Apr 08, 2015 8:18 am

I have a few .049's with the copper or brass reed that has the four points on it and is mounted under the round circlip. Can these be replaced with a different material? I had a really bad running engine yesterday and found the well-worn reed slipped out of center under the spring and was essentially useless for operation. I bent it up a bit accidentally and reinstalled it flipped over and the test run went well.

Would the new shaped rectangular mylar reed work as a replacement? Is a manual blow and suck test sufficient to tell if the reed works on the plate?

Thanks! Greg
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Re: Old-Style Star Reeds

Post  rogermharris on Wed Apr 08, 2015 8:34 am

cox international has a few different ones. not sure what is preferred as i'm used to the old copper ones i purchased their overhaul kits for some engines i picked up. they have all the gaskets, new reed vale and clip ect.

http://coxengines.ca/back-end/index2.html
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Re: Old-Style Star Reeds

Post  1/2A Nut on Wed Apr 08, 2015 8:47 am

The Mylar reeds can provide more rpm and hold up a better seal over time Small Cox Logo
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Re: Old-Style Star Reeds

Post  rogermharris on Wed Apr 08, 2015 9:06 am

1/2A Nut wrote:The Mylar reeds can provide more rpm and hold up a better seal over time Small Cox Logo


cool.. i will have to add some extras to my next order
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Re: Old-Style Star Reeds

Post  balogh on Wed Apr 08, 2015 12:37 pm

1/2A Nut wrote:The Mylar reeds can provide more rpm and hold up a better seal over time Small Cox Logo

I concur, and have read here on CEF somewhere that after the original, beryllium star reed, out of the different reed alternatives the ranking is as follows:

1. The mylar reed is the best for maximum performance as this provides the best sealing, is of the lightest weight and thus allows the highest open-close frequency (same as rpm)

2. second best is the stainless steel reed, a bit heavier than the mylar, but will last the longest due to its material properties

3. third best is the teflon which is lasting and light but its surface is not as smooth as Nos 1 and 2 thus sealing properties are inferior

No matter which one is used, but if fixed with a circlip, one must make sure it moves/rotates freely under the circlip to allow free movement when closing/opening.
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Re: Old-Style Star Reeds

Post  Sig Skyray on Wed Apr 08, 2015 1:07 pm

Great info on the reeds. Thanks!

Greg
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Re: Old-Style Star Reeds

Post  roddie on Wed Apr 08, 2015 1:25 pm

Sig Skyray wrote:I have a few .049's with the copper or brass reed that has the four points on it and is mounted under the round circlip.  Can these be replaced with a different material?  I had a really bad running engine yesterday and found the well-worn reed slipped out of center under the spring and was essentially useless for operation.  I bent it up a bit accidentally and reinstalled it flipped over and the test run went well.

Would the new shaped rectangular mylar reed work as a replacement?  Is a manual blow and suck test sufficient to tell if the reed works on the plate?

Thanks!  Greg

I always use the blow/suck test after installing any reed. Some of the members here have "thinned" their circlip-type reed-retainers for use with thicker reeds by sanding the backside of the clip, to prevent binding and permit the reed to rotate freely when the clip is installed.

The thicknesses of the different materials used for reeds varies significantly.. (as much as .009" in my experience)

Copper (star)=.001" thickness
Steel (rectangular)=.002" thickness
Mylar (both; star and rectangular)=.005" thickness
Teflon (rectangular)=.010" thickness

The newer-style "plastic" reed-retainers would seem to be designed to establish the optimal "gap" for the .005" thick "Mylar" reed to operate correctly, when used in the reed-housings designed for that retainer. Keep in mind; that the original circlip-retainer and the "groove" in the housing that it sits in.. establishes the optimal gap for the old Copper (star) reed which is .001" thick.

In closing; the "Steel" reed is said to wear the anodizing off the seat.. but I don't know how much time it takes for this to happen.. or whether it only happens in a high-performance application.
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Re: Old-Style Star Reeds

Post  Sig Skyray on Wed Apr 08, 2015 2:31 pm

roddie wrote:

I always use the blow/suck test after installing any reed. Some of the members here have "thinned" their circlip-type reed-retainers for use with thicker reeds by sanding the backside of the clip, to prevent binding and permit the reed to rotate freely when the clip is installed.

The thicknesses of the different materials used for reeds varies significantly.. (as much as .009" in my experience)

Copper (star)=.001" thickness
Steel (rectangular)=.002" thickness
Mylar (both; star and rectangular)=.005" thickness
Teflon (rectangular)=.010" thickness

The newer-style "plastic" reed-retainers would seem to be designed to establish the optimal "gap" for the .005" thick "Mylar" reed to operate correctly, when used in the reed-housings designed for that retainer. Keep in mind; that the original circlip-retainer and the "groove" in the housing that it sits in.. establishes the optimal gap for the old Copper (star) reed which is .001" thick.

In closing; the "Steel" reed is said to wear the anodizing off the seat.. but I don't know how much time it takes for this to happen.. or whether it only happens in a high-performance application.  

Wow, I'm amazed at the knowledge here at CEF. Thanks everyone for being so generous with your wisdom. That's "need-to-know" info on the reeds.

One question... are they still making the star reeds or are they obsolete and just found in older engines? I have not seen them around. If they are, are they preferred over the rectangular?

Greg

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Re: Old-Style Star Reeds

Post  pkrankow on Wed Apr 08, 2015 2:49 pm

The rectangular / oblong reed has more open area than the star reed so it is the preferred reed.

There are Mylar star reeds that run nice (I have a few from old engines) I have not tached these engines as they are not powerful configurations to start with.

Phil
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