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Mylar/Stainless steel reeds with circlip-type reed retainer Empty Mylar/Stainless steel reeds with circlip-type reed retainer

Post  balogh on Fri Jul 24, 2015 2:48 am

I have a few old COX reedies designed originally for the star-shape beryllium reeds.

Once I replace the old star reed with a mylar or stainless steel reed, I feel these are a bit stuck under the circlip, being obviously thicker than the beryllium (the groove for the circlip is too close to the reed seat bottom and thus will not allow an unobstructed float of the thicker mylar or stainless steel reed).

As a consequence, the suck-and-blow test shows it takes a larger depression in the crankcase to open the mylar and stainless steel reed valve than it takes for the beryllium, and the charge of the engine will be less. I derive this will have a negative impact on the engine output...

Any advice on how to enable the mylar/stainless steel reeds to float better under the circlip retainer, and experience on possible output deterioration with the myler/stainless/circlip combo, from any one of you will be appreciated.
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Post  andrew on Fri Jul 24, 2015 8:13 am

One quick thing to check is the circlip itself and make sure it's not flipped over. It snaps into the retainer one way and the center tang will hold the reed in place if the clip is upside down.
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Post  getback on Fri Jul 24, 2015 8:15 am

I don't use the SS ones but have noticed ,and this had come up before that they are cut a little long and tend to bow when installed, simply lightly sand the rounded edges till fit is correct to let it float as intended with the clip installed with the protruding of the clip out so as not to press on the reed . Eric Very Happy Andrew said that right, Thanks
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Post  Jason_WI on Fri Jul 24, 2015 8:18 am

Older OEM circlips were thinner wire diameter than the replacements available today. If you replaced with a thicker dia circclip I have seen this happen where the Reed is stuck. Find a thinner circlip and it should be fine.
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Post  balogh on Fri Jul 24, 2015 8:18 am

Thanks
The center part is not flush and it elevates from the reed so it is OK. I think the mylar is too thick and overlaps the groove so the clip holds it down too strongly
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Post  balogh on Fri Jul 24, 2015 8:20 am

Thanks Jason I think this is stock clip but will compare with another
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Post  getback on Fri Jul 24, 2015 11:39 am

Thanks for bringing that up Jason , I have seen this in some engines I have bought /cleaned , but have now bought any new circlips for lack of need . Eric
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Post  TDbandit on Fri Jul 24, 2015 11:56 am

Another thing you can do is face the clip, it takes a little time, trial and error but I've done it just make sure its even.
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Post  roddie on Fri Jul 24, 2015 7:56 pm

I have heard that the steel reeds can wear the anodizing off the seat. I can't speak from experience though. I do have some steel reeds.. and they're only .001" thicker than the original copper-star type. My Mylar reeds measure .005" in thickness. My steel reeds measure .002"... and the old beryllium/copper type measure .001". You're really going to see a difference with the Mylar type in this application.

Something to try.. (I plan on trying this..) is to thin-out the backside of a circlip, like Bandit mentioned. To do this evenly would be very important... so I got to thinking of a way to attempt it. If you have an oil-stone.. that would probably work best. A 3/8" diameter hardwood dowel will fit inside the circumference of the circlip. If you cut a piece about an inch long and slot one end "on-center" for the clip's "tang" to fit into.. you can then chuck it into a VSR hand drill.. and spin the clip on the stone with some cutting-oil using low speed for a few seconds at a time.. while stopping to check the fit until you achieve the right clearance for the reed you plan to use. If you have a set of vernier/calipers.. you can measure for the amount of material you are removing. It will only need to be a few thousandths of an inch.. (approximately .1mm or less) depending on the reed-thickness/clip-wire diameter.

A standard hacksaw-blade works well for cutting the shallow slot. I seem to have misplaced my oil-stone though..

Mylar/Stainless steel reeds with circlip-type reed retainer 3-8_do10
Mylar/Stainless steel reeds with circlip-type reed retainer 3-8_do11
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Post  balogh on Sat Jul 25, 2015 1:12 am

Thanks Roddie A good idea. As a simplistic man I would have just rubbed the clip on a flattened fine grit sandpaper
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Post  RknRusty on Sat Jul 25, 2015 1:51 am

balogh wrote:Thanks Roddie A good idea. As a simplistic man I would have just rubbed the clip on a flattened fine grit sandpaper
Me too, in fact I did just that the other day. I have several grits spray-glued to my table top. But Roddie is an inventive man of precision. And if we took the small amount of time to make his simple special tools, we might be able to perform many tasks quicker and better.
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Post  roddie on Sat Jul 25, 2015 9:12 am

RknRusty wrote:
balogh wrote:Thanks Roddie A good idea. As a simplistic man I would have just rubbed the clip on a flattened fine grit sandpaper
Me too, in fact I did just that the other day. I have several grits spray-glued to my table top. But Roddie is an inventive man of precision. And if we took the small amount of time to make his simple special tools, we might be able to perform many tasks quicker and better.
Rusty

Thanks Rusty/Andy.. Rubbing by hand on fine-grit sandpaper would work fine too. I've often wondered whether a reed "itself" could be thinned by placing it in-between two blocks faced with fine paper.. and twisting the blocks. Maybe even try applying some rouge and use two small flat steel blocks without any paper applied?

Of course.. Mylar probably won't take well to sanding.. and being the "thicker" material that it is; might float during operation if thinned too much. I don't know. I imagine that there's an optimal "flex-factor" between the different reed materials.. or there wouldn't be the different thicknesses. Too rigid.. and it won't flex enough to open/operate.. and to flexible, it will begin to float at less than optimal engine rpm.

Here are examples of the differing wire sizes between my .049 circlips.. just to prove that it will make a difference in which clip is used for a particular reed thickness.

The thinner wire would be your best choice with a thicker reed.

Mylar/Stainless steel reeds with circlip-type reed retainer 028_wi10
Mylar/Stainless steel reeds with circlip-type reed retainer 031_wi10

This .033" diameter wire (below) would likely be your best option for the vintage thin copper reed.
Mylar/Stainless steel reeds with circlip-type reed retainer 033_wi10

I would imagine that Cox originally designed the reed-retention system around the standard .031" wire size back in the early days. Whether they specified a +/- .001" max tolerance in the wire-size from the vendor, is something that we can only wonder about.

I realize that not everyone has a vernier/caliper to measure with.. but they are great for things like this.
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Post  Ken Cook on Sat Jul 25, 2015 5:27 pm

That is a very nice caliper. Brown and Sharpe are my favorite tools
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Post  Cribbs74 on Sat Jul 25, 2015 6:18 pm

I brought this up a few years back.

In the end as long as the reed can rotate freely 180 degrees in the reed holder then I guess it doesn't matter how you do it.

As for sanding the reed itself, I would be worried that the edges of the reed would become "fuzzy" I've never tried it so it may work.

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Post  roddie on Sun Jul 26, 2015 1:18 pm

One more thing... if you happen to try using a different/used circlip/reed combo.. make sure they've been cleaned with solvent. I use a solvent-soaked Q-tip (cotton swab) to clean my reeds (and seating area). A small flat piece of rubber makes a good base to lay the reed for cleaning.. and helps to keep it from sliding around while swabbing it. This can also help to avoid bending/creasing a fragile copper reed. That type can be ruined with discouraging ease. Lifting any reed from a flat surface can be challenging. I usually try pressing my index finger against the center of a reed to pick it up. It will usually stick for a second or two.. long enough to drop it onto the palm of your other hand where you can carefully lift under an edge with tweezers.

Andreas, I hope you don't mind me having mentioned these tips here. I thought that were relative to the topic.. and although some people may know these things already.. some may not.

Were you able to achieve a good fit/seal?
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Post  balogh on Sun Jul 26, 2015 2:23 pm

Thanks Roddie any advice is appreciated. Sometimes the solution to a problem hides in tiny details one would not even think of.

The clip and the reed both are immaculately clean so I will resort to thinning the clip.

Looking at the flanged cap type retainers one would wonder how the reed that freely travels a long way between the reed seat and the retainer cap can efficiently seal as for a significant time while it flies back towards the seat when the piston moves down and develops pressure in the crankcase the reed is open and some charge will inevitably be pushed our of the crankcase? I would think the old reed retainer design where reed travel is limited more by the clip should be a more efficient design That is why I try to combine the mylar with the circlip.
What is your opinion?
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Post  roddie on Sun Jul 26, 2015 4:59 pm

balogh wrote:Thanks Roddie any advice is appreciated. Sometimes the solution to a problem hides in tiny details one would not even think of.

The clip and the reed both are immaculately clean so I will resort to thinning the clip.

Looking at the flanged cap type retainers one would wonder how the reed that freely travels a long way between the reed seat and the retainer cap can efficiently seal as for a significant time while it flies back towards the seat when the piston moves down and develops pressure in the crankcase the reed is open and some charge will inevitably be pushed our of the crankcase? I would think the old reed retainer design where reed travel is limited more by the clip should be a more efficient design That is why I try to combine the mylar with the circlip.
What is your opinion?

That's a really good question.. and one that I've pondered myself. There's quite a science to reed-induction vs. rotary-valve. Ron Cribbs prefers the reed to rotate freely under a circlip. I tend to agree with his way of thinking. The "cap-style" plastic flanged-retainer I believe is designed around the later .005" thick Mylar "oblong" reed.. I'm curious as to the "design-gap" in this style retainer. The reed is not held by a clip at it's perimeter.. but allowed to "float" within a gap.

The original Cox "star-shaped" beryllium/copper reeds have 4 symmetrical legs extending out from the center which are retained by the circlip. Did this act as a "suspension-system" when the reed lifts off it's seat on the intake stroke? The seat-area is smaller and symmetrical; as compared to the "two sided" oblong reed. The fuel-charge enters through 4 equally-radiussed points.. compared to the oblong's two blunt-straight sides. Both work.. but I've heard that the thin star-shaped/copper-beryllium reed will start to "float" at higher rpm's.  

I have some Cox circlip-style horseshoe backplates. The early postage-stamp plastic backplates I think used a higher-quality plastic (Delrin?) than the later horseshoe type.. and as a result; the plastic would fail/crack in the circlip seat area. I have some horseshoe backplates with this condition. I also think that they came with oblong Mylar reeds.. unlike the postage-stamp type. So.. was the circlip-gap increased in the horseshoe backplate; to accommodate the thicker reed?

At some point.. a star-shaped Mylar reed was introduced. I have one.. and it's .005" in thickness. I believe it's from an early white-plastic "circlip-style" horseshoe backplate with an aluminum needle.

Here's that backplate..

Mylar/Stainless steel reeds with circlip-type reed retainer White_10
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Post  balogh on Sun Jul 26, 2015 5:29 pm

Thanks. The gap in the flanged retainer is just too large and probably is not designed so to acommodate the thicker reed. Maybe it is safer to mount the reed without damaging it than with the circlip...
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Post  Dane Martin on Sat Feb 27, 2016 5:26 pm

So just to verify the Circlip direction, it sits in the groove, and the bent tang in center faces "up" where it's not holding the reed down, correct?
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Post  NEW222 on Sat Feb 27, 2016 6:29 pm

Correct! If not sure if it is in good just give the reed seat the blow/suck test to see if it seals appropriately.
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Post  Dane Martin on Sat Feb 27, 2016 7:04 pm

Ok, just making sure i haven't lost my mind! I tried two different reeds on my 020 and both failed the suck / blow test. However, they're used and probably just no good. I've already ordered kits from cox so I'll be good
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Post  happydad on Sat Feb 27, 2016 7:57 pm

Dane Martin wrote:Ok, just making sure i haven't lost my mind! I tried two different reeds on my 020 and both failed the suck / blow test. However, they're used and probably just no good. I've already ordered kits from cox so I'll be good

Just checking, but is the circlip in correctly? There should be a space between the clip straight piece and the reed. Also make sure there is no debris, dust, old dried fuel, etc. on the reed causing a non-flat surface. Sometimes after you have taken all the precautions there is a tiny piece of dirt on the bottom of the reed.

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Post  Ken Cook on Sat Feb 27, 2016 8:27 pm

Try flipping the reed over and test again.
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Post  Dane Martin on Sat Feb 27, 2016 8:36 pm

You know I'm just going to tell you guys all the same BS, I've been running these forever, i cleaned it good, blah no blah.... HAHA!!
Ok, I'll try cleaning it again, I'll scrub everything with a tooth brush, and then put it back in Cake's (the wife) tooth brush holder. I like her, i like nitro.. Maybe a good combo!
Ah! As I'm rambling, i pulled it apart and see an indentation in the reed. That's gotta be bad, right?
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Post  getback on Sun Feb 28, 2016 6:45 am

Dane Martin wrote:You know I'm just going to tell you guys all the same BS, I've been running these forever, i cleaned it good, blah no blah.... HAHA!!
Ok, I'll try cleaning it again, I'll scrub everything with a tooth brush, and then put it back in Cake's (the wife) tooth brush holder. I like her, i like nitro.. Maybe a good combo!
Ah! As I'm rambling, i pulled it apart and see an indentation in the reed. That's gotta be bad, right?
RIGHT , WAIT ON YOUR KITS AND ALL WILL BEE GOOD .getback Small Cox Logo
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