Boysen Reeds

[betablounty]

has anyone tried out the Boysen Reeds on a 08 250??

they fit and how do they perform??

wouldnt be suprised if Heath has tried them hes got everything else!!

cheers

Jono

[dan williams]

Not Boysens but VForce3s, same as I have on my '05. They have the same effect on the '08. It'll pull a gear higher and lugs like a four stroke at low RPMs. I won't ride without them.

[betablounty]

Not Boysens but VForce3s

whats the difference??anyone know??

[jezza]

With Boyesens you just get the reeds which are dual stage. The original reeds in the Beta are single stage, ie one reed on the top, one reed on the bottom. Boyesens have two reeds on top and two on the bottom. The first reed opens at lower revs and the second as the revs build. They come with a reed plate which is different than the original one. The original reed plate is shaped like half a semi circle and limits the reed travel. The Boyesen reed plate just secures the reeds where they screw onto the reed block and is a flat plate. Total cost about

[jse]

Not sure of the internal details of the V-force as not had one to look at but am sure someone else will come on here and help out.

I guess I'll poke my nose in here (I know, as usual)....

Some time ago (geez, it's got to be 10 years or so) , one of my Pro riders came back from Belgium with two of the reed cages for us to test. The were made by Moto Tassanari (I understand now V-Force) and had not been released to the public yet. They performed very well and are essentially two reed blocks stacked on top of each other and the idea is that, simply put, with the added surface area (four-sided), you will get essentially double the amount of flow at the same reed opening measurement of a single (two-sided) reed block. There are other details relating to Fluid Dynamics, Harmonics blah, blah, blah, that make them work well, but the main reason, as I understand, is increased flow at low tip openings.

Boyesen reeds also work well and to my knowledge, they are the only true "dual-stage" reeds as Eyvind Boyesen still has an active patent on the design.

Jon

Edited April 11, 2008 by JSE

[dan williams]

The stock Beta reeds are four petals as well. The main point of the VForce or any carbon reed is the lower mass of the petal allows it to open and close with less pressure then the standard fiberglass reeds. This means the carbon reeds open faster to let in more mixture and close faster to hold more charge in the crankcase and let less blowback through the inlet tract at low RPM. At high RPM the reeds are always open so the design of the reed block comes into play but in most engines there is more then enough power at high RPM even given a less then optimal flow through the reed block.

[jse]

The stock Beta reeds are four petals as well. The main point of the VForce or any carbon reed is the lower mass of the petal allows it to open and close with less pressure then the standard fiberglass reeds. This means the carbon reeds open faster to let in more mixture and close faster to hold more charge in the crankcase and let less blowback through the inlet tract at low RPM. At high RPM the reeds are always open so the design of the reed block comes into play but in most engines there is more then enough power at high RPM even given a less then optimal flow through the reed block.

You're correct, the Beta is four petals, but still only a two-sided reed block, whereas the V-force is four-sided and often eight petals.

I think the V-force block is significantly different and it's function is irrespective of the reed material-carbon fiber-which is common now in reeds used in Trials engines. Even just considering the reed petal itself, the use of carbon fiber is only one of the factors that dictate it's performance and some other considerations are the weave pattern, resin composition, petal width-length-thickness, radius at tip, free length vs. clamping footprint etc.

I didn't want to get too complicated in discussing the V-force, but here's another thing to look at: the angle of the block where the reeds sit in relation to the centerline of the block is called the "half angle" in block design. The V-force is not simply two blocks together but the centers are angled inward on purpose, so beside the doubling of effective tip area, the design helps to shape the fuel/air charge and therefore maintain it's velocity

Jon.

[jse]

... question still remains. What about on an 08 with the larger inlet tract? As far as i can see it reduces the size of the inlet. (v-force reeds i mean)

My guess is that the V-force you have is designed for the smaller carb on the earlier models. You may want to return it or if you want to use it, you'll need to enlarge the inlet on the block to fit the manifold. I assume that, when the inlets are matched, it should work fine but I'd have to look closely at the block to be sure.

Jon

[jse]

... it fitted my 05. so do they do a new version for the 08 then?... what model code is it?

I just looked up their website: http://www.mototassinari.com/ and didn't see any applications for specific bikes. You may want to contact your Beta dealer, I'm sure they will be able to find out.

Jon

[dan williams]

Oh yeah, forgot the extra four petals in the VForce but the point remains that the lower petal mass is what has the most effect on low RPM power. Additional surface has two effects, making it easier to get high flow through the block and allowing smaller petals. The Beta doesn't have carbon fiber reeds stock. They paint them black but under a microscope it's pretty clear the fibers in the matrix are glass. In any case my original statement still stands that having the VForce gives a lot more grunt to the Beta. It almost feels like cheating.

[jse]

Oh yeah, forgot the extra four petals in the VForce but the point remains that the lower petal mass is what has the most effect on low RPM power. Additional surface has two effects, making it easier to get high flow through the block and allowing smaller petals. The Beta doesn't have carbon fiber reeds stock. They paint them black but under a microscope it's pretty clear the fibers in the matrix are glass. In any case my original statement still stands that having the VForce gives a lot more grunt to the Beta. It almost feels like cheating.

Point well taken. You're right about the carbon reeds making a big difference and they are one of the reasons that allows the V-force to work as well as it does. The Tassanari prototypes were phenolic/fiberglass reed composition as carbon was relatively rare at the time. Like you say, the reed/manifold setup can have a big difference in low-end power delievery, even in older bikes. I don't know if the photo will process, but it's of a one-piece aluminum manifold/reedcage for a TY350 I made years ago using lost wax casting (like jewlery is made) and used 6 dual-stage reeds. It made a significant change in the throttle rsponse.

Jon

[dan williams]

Wow, that's a pretty piece of work. You're hard core Jon.

[jse]

Wow, that's a pretty piece of work. You're hard core Jon.

Thanks, Dan,

Sometimes I think I'm more nut case than hard core.

Here's a shot from the other side.