Flash's Carbonized Reed Valve

[Wheelman-111]

Greetings:

No not from excessive oil or a rich mixture, but Home-made organic Carbon replacement reeds:




From the top L, there's the NB50 reed cage, a rough-cut slice of ProTech Composites 0.5 mm thick sheet, the metal stock reed, and the reed-stop plate. Below are the uncut 0.25mm and a cut piece of the 0.5 material.

Working only with a nice pair of shears from Harbor Freight and this file set:




Which complements my standard tool kit consisting of a couple of pointed sticks and a big rock.

The end result photo couldn't suck worse, but here it is:




The 0.5 mm stuff is considerably stiffer than the stock steel reed, as well as lighter. The 0.25 felt approximately the same stiffness, and of course both are much lighter than steel.

In the end I decided to go with the 0.5, thinking it would have more resilience. It also seemed to seal a lot better. Blowing softly through the snorkel (KIDS!, I am a trained Professional. Don't try this at home!!! Gasoline residues contain substances known to the State of Kalifornia as Cancer-Causing! The State of Kalifornia contains individuals known to the rest of us as being a giant pain in the behind.) produced a nice D Sharp note. If the intake had more holes I could play Birdland.

How's it run, you ask? It started up fine. Too rainy to conduct GPS-Assisted Performance Evaluation. (GAPE) I should know something tonight. Either she'll run or I'll be pushing it home.

The Bike is a red 1987 NB50 Aero, Flash Scootertrash. Thanks for reading.

[noiseguy]

Where did you end up sourcing the carbon fiber material?

[Wheelman-111]

Greetings:

See also 1st photo, such as it is. They had a "Sample Pack" of 4 thicknesses: 0.25, 0.5, 1.0 and 1.3 mm. for $16, shipped. Google it.

[scooterwerx]

very nice! as i understand, the stiffer material should give better high rpm power, while a more flexible reed yields more opening at lower rpms, giving good flow but staying open completely at higher engine speeds. happy tuning!

[ALOW1]

From the top L, there's the NB50 reed cage, a rough-cut slice of ProTech Composites 0.5 mm thick sheet, the metal stock reed, and the reed-stop plate. Below are the uncut 0.25mm and a cut piece of the 0.5 material.

Greetings:

See also 1st photo, such as it is. They had a "Sample Pack" of 4 thicknesses: 0.25, 0.5, 1.0 and 1.3 mm. for $16, shipped. Google it.

Yeah, that's why I'm asking. I can't read the distributor's name.

[Wheelman-111]

Greetings:

See subject line. Some of my best material is in there...

ProTech Composites.

[Kenny_McCormic]

very nice! as i understand, the stiffer material should give better high rpm power, while a more flexible reed yields more opening at lower rpms, giving good flow but staying open completely at higher engine speeds. happy tuning!

As I understand the stiffer stuff should give better LOW-mid rpm power because the smaller opening will give higher velocity. IIRC according to bear the reeds are stuck full open and dont move at full throttle.

[Bear45-70]

Are you running the stock reed stops with the carbon reeds? Normally you don't use reed stops wih other than metal reeds. At least I wouldn't.

[Wheelman-111]

Greetings:

I used the reed stop mainly as an easy method of attachment. The carbon is quite stiff. Because it is also so light, it does not carry much momentum. I don't think the intake pulses are strong enough to cause the reeds to bend open so far as to make contact with the stops under any circumstances even at 167 times per second. (10,000 RPM)

If they do make contact with the reed stop, that contact will be softer in nature than the collision with the reed cage upon closure. Furthermore, the presence of a reed stop ensures the reeds don't open too far. Carbon is tough but brittle as you know. Exceeding its elastic limit means nearly instantaneous and complete detachment.

That last thing gives pause, but I think the same can happen with metal, which brings worse consequences as the broken parts make their way through the transfer ports... Carbon is less likely to cause severe damage.

Anyway, yes I did install the reeds with the stops. I was thinking about a post of brother Bear's when I considered carving little windows into the .02" material and adding a primary stage layer of the .01. I decided the size of the reed passages was just too small to justify this. Too easy to break off little corners here and there.

Another option would be to make one reed out of .01 and the other from .02. My old XL 600R Thumper had two (Count 'em, 2) carburetors on a single-cylinder engine. Two exhaust pipes, too. That bike ran so sweetly and predictably all through its range, thanks to high intake velocities through the little "primary" carb at low speeds, then a major top-end rush as the big secondary opened up.

More after testing tonight.

[Bear45-70]

At higher rpms the reeds do not open and close but just sort of hang open as the velocity of the air flow prevents any reverse air flow back thru the reeds. And I would bet you are loosing some high end air flow with the stops. Just cut off the reed stops and round the edge where the reed will flex is a better way to go.

[Kenny_McCormic]

At higher rpms the reeds do not open and close but just sort of hang open as the velocity of the air flow prevents any reverse air flow back thru the reeds. And I would bet you are loosing some high end air flow with the stops. Just cut off the reed stops and round the edge where the reed will flex is a better way to go.

Or take half off and bend carefully.

[timcat]

guys im learing much from this discussion but may i ask this ? is it ok to run with no cage as i guess its called with just the reeds bolted to the reed box ? its sounding like this makes things maby work better at top end speed

[burnt_toast]

At higher rpms the reeds do not open and close but just sort of hang open as the velocity of the air flow prevents any reverse air flow back thru the reeds. And I would bet you are loosing some high end air flow with the stops. Just cut off the reed stops and round the edge where the reed will flex is a better way to go.

hmm interesting.. i may have to experiment with this

[Bear45-70]

guys im learing much from this discussion but may i ask this ? is it ok to run with no cage as i guess its called with just the reeds bolted to the reed box ? its sounding like this makes things maby work better at top end speed

Yes, but you need some kind of metal over the base of the reeds where the hold down screws go or the reeds will break around the small area of the screw heads. Boyesen supplies a small plate with their reeds.

[Wheelman-111]

Greetings:

I hate to disagree with brother Bear, wise is he. Negative on cutting the cage because I don't wish to do anything irreversible - just experimenting with carbonation.

Ill go even farther and point out that the cage on this particular design is completely out of the airflow. Also on my bike the reeds are clearly not the main factor limiting top end.

Finally - here it comes - a reed valve engine design that converts to port-controlled at top RPM clearly needs better reeds . These are capable of hitting a high note - think party favor - and so I believe they continue to keep up with the intake pulses and close on cue up to and perhaps beyond this engine's rev capability.

Theory is all fine and dandy, but here's how it ran:

1. Started normally, required a slight idle speed adjustment.
2. Midrange torque such as it is - hey my other bike is an HD 1200 Sportster! -was distinctly stronger.
3. Throttle response felt crisp and instantaneous where it was lazy before.
4. Top end improvement was an underwhelming 45.4 - up from 44.6. I do not think the speed improvement alone is significant enough to justify the effort. It may be due to Weather or even random factors. The throttle response DOES justify the effort for me.

Can't speak to durability. Yet - only 15 miles with carbon so far...