Flash's Carbonized Reed Valve

[Bear45-70]

Your would be wrong, on two counts. First off they are not a cage but a stop which limits how far the reed can open. You will break or at least kink metal reeds if you don't run stops. Second the air does 2 seperate 90° turns with this reed design so they are in the air flow by design. A "V" block reed cage design causes only small deviations from a straight line air flow thru the reeds.

[mousewheels]

Wheelman,
Thanks - plenty helpful for those who have scooters that don't support by Boyesen. Hand tools and Harbor Freight we should all be able to rise too, and your finding that sampler kit of carbon is handy.

I have a set of Boyesen reeds for a Yamaha 50 and it came with a little shim like Bear is talking about. But I recall from the diagram at least for my model, they put it on top of the reeds, but under the reed stop. So it let the reeds open a tiny bit more. Someone could experiment with that sort of setup, with less risk of reed breakage. The shim is not very thick - under 0.032...

[Bear45-70]

All the fiber reeds we ever installed in outboards, stock or racing, were installed without the reed stops. If the fiber reed breaks it just goes through the motor and hurts nothing. The reason for reed stops with metal reeds is so they won't break, because they do not pass through the motor without causing damage.

[Wheelman-111]

Greetings:

Wish I had my camera and parts disassembled to illustrate.

On my bike, the intake manifold ("Snorkel") does indeed bend 90 degrees on its way to the reed block. Mixture/air from the carb first flows forward and down, turns right into the reed block. From there, the incoming air encounters the opening in the plastic reed block and the two closed reeds:




The reed block is at the top left, and sits upside-down with respect to what the mixture flow "sees". On my engine, the ports leading into to the crankcase are horizontal, with openings facing Left.

I submit that when the reeds open, like a trap door hinged from the left side of the case, the air has a STRAIGHT shot into the case port. The reeds swing down and out of the way. The reed stop is UNDER the reeds and is NOT in any way a factor disrupting the airflow. At All. I also submit that the stop permits the reeds to open farther than necessary to make an unrestricted pathway for the mixture. The case ports are only about 3/8 of an inch "high", and the reeds can open wider than that even with the reed stop. Shimming them as MW described would not make a bigger opening for the mixture because the case ports themselves are the limiting factor.

I thought of going in there with trusty Roto-Zip and opening things up a bit, but I hear Aluminum dust in the case might be bad for bearings and bore, so I demurred on the de-burr. Maybe if I someday split the cases I'll give that a try.

NGAPE Performance Report: (Non-GPS-Assisted Performance Evaluation)

The speedometer needle touched the "1/2" mark on the fuel gauge on the way to work today:




I think that's about 46, certainly faster than I've ever seen before, making this Polini 65 2-stroke almost as fast as my old CT-70 with a proper All-Metal-Gear transmission. Woo-Hoo!

[scooterwerx]

i opened up those ports on mine, i filled the case with 90wt gear oil and stuffed rags around the crank to prevent al filings from entering the crankcase, then washed everything out with solvent. worked well, and it still runs! i was considering splitting the cases but opted for the quick and dirty route. i have also been considering matching the bottom skirt of the cylinder to the ports, since the way it is now, the cut out in the side of it limits about 25-30% of the opening's area...i opened up the boost port to match the malossi cylinder, that helped out alot in low end power.

[Wheelman-111]

Greetings:

Thanks for giving me something to think about, Werx. Got Pics?

How'd you score a Malossi for your NB/SE50? All I could find was the Polini Contesta 47mm. How do they compare?

[scooterwerx]

it worked! just gotta be careful no swarf gets down in the case...

i have been curious about how the polini and malossi cylinders would stack up head to head...we should both ride to El Paso and race!!! its halfway! i think im going to get the polini cylinder for my elite E/nb50 swap. the malossi cylinder i have is ported and port matched, so if performs very well. with the gears and a 90\90 10 tire it pulls like a train and wheelies everywhere. i did score a leo vince sp3 on ebay uk, so ill see how much improvement can be had.

i got the malossi from roselle european imports in new york. Vigro is da man! he hooked me up proper, now i order all sorts of stuff from them.

[Wheelman-111]

Greetings:

Aah-Hah!! So you're the rat basket what stoled my LV muff out from under me!

That thing came off eBay faster than Britney's knickers at a margarita party. He who hesitates as they say... I am consoled only by the thought of what you paid for shipping.

Race in El Paso? That fair hamlet is 21 hours from here in Deepinnaharta. At 80 MPH. Big state!

So you got your NB50 Malossi cylinder from Vigro @ Roselle? I wish it was easier to contact them online. Did you have to phone the order in?

Maybe the moderators should consider adding a "Parts Source" section to the Forum? Have all the links or phone numbers in one place so we could browse & shop more easily. The stores might even want to contribute something back. Just a thought.

Back to my Aero; it now keeps up with urban surface street traffic just fine, runs 46+ but it sure won't wheelie. Whatcha got in yours to make it so? Built carb and CT reed block/adaptor makes that much difference?

[scooterwerx]

ohh yeahhh!!!! the shipping was outrageous but i supose it should be worthwhile, the d*** shipping was almost as much as the pipe!!! i got snaked a while ago for one that daywot had for 175, so this time i had to jump on it! im still going to build one for my other nb, so if it works out maybe ill sell it at a discounted price....someday!!! ahahah

much searching it took to find that cylinder...malossi only sells wholesale, and all of their US distributors needed minimum orders and such, but by chance I got transferred to Vigro, i think by accident, and i told him what i needed and BAM it was here!

I think the thing that made my motor come to life, well i know it is, is the porting. the stock porting is conservative bordering on boring. the transfers and boost ports are tiny stock, and just doing these improved performance tremendously. the exhaust port is good, but the duration is wimpy and it could be wider. i noticed a huge difference after doing these vs. just bolting it on. the 21mm carb was also like night and day. low end and top end improvements. im thinking im going to need a bigger carb with the LV pipe, seing as the stock exhaust is so terribly restrictive and awful.

[Wheelman-111]

Greetings:

The Polini piston/cylinder is 47. I have read there's scarce room for more. Is the Malossi 47 also?

[scooterwerx]

yep. 47 looks like about as big as it gets. i do have a spare overbore piston thats 47.5mm!!! not that itll make a difference. the d*** head studs are too close together!

[Wheelman-111]

Greetings:

Carbon reeds @ 0.5 mm helped low end. Just switched to 0.25 and bent the reed stopper down a little and found more power on top. Same midrange and a little softer low end.

I can make both thicknesses for anyone wanting to try this. Send me your stock steel ones for a template. $20. shipped. See WTB thread.