v-force reed valves

[recessionracing]

are they worth buying for the rs125?

[Craig H.]

I installed them, and I did notice a more crisp throttle response...hard to tell if it did anything else just using my "butt dyno".

Craig

[maddad]

I Like them ,I did space the manafold out 5mm with a plate and cleaned up where they dont line up properley ,Although this thing sits on 10 k almost all the time.Reason for the spacing is to stop the flutter and the reeds freying at the end.It's a theory still good after 400ks on the track.

[Craig H.]

I Like them ,I did space the manafold out 5mm with a plate and cleaned up where they dont line up properley ,Although this thing sits on 10 k almost all the time.Reason for the spacing is to stop the flutter and the reeds freying at the end.It's a theory still good after 400ks on the track.

Please explain what you cleaned up. I totally removed the "sticking out part" of rubber on the stock manifold. Why would the reeds flutter, and how would spacing 5mm change anything? Just askin!

Craig

[maddad]

This is what is needed to fit the VForce,The 5mm is to give a bit more volume to the crank case and take the reeds further away from the turbulence.

[Craig H.]

Yea, that is what I did. Increasing the volume of the crankcase will only decrease the scavenging pressure. We used to actually try and decrease the volume of the crank case in order to increase the scavenging..."crankcase stuffing".

Craig

[maddad]

I could try without the spacer for the last race of the year 1 round to go this things topping out at 11k rpm I'm a happy camper.

[2T Institute]

Yea, that is what I did. Increasing the volume of the crankcase will only decrease the scavenging pressure. We used to actually try and decrease the volume of the crank case in order to increase the scavenging..."crankcase stuffing".

Craig

Care to explain why a RSA/RSW 125 has 650cc case volume? That thinking went out with points ignitions. A Rotax Max kart engine loved a thick gasket between the reed and cylinder

[Craig H.]

The actual size of the case volume, I am sure, is fully calculated by the engineers and designers and is designed to get the job done. As the piston moves down, it compresses the fuel/air/oil mixture in the crankcase and that mixture is forced up into and across the now "empty" cylinder. This mixture is what pushes the exhaust gases out. That whole process is call scavenging. By reducing the volume of the crankcase, the pressure is increased when the piston comes down. The mixture is forced at a higher pressure into the cylinder, thus increasing scavenging. I am not sure if this will have any effect on a Rotax, but I can almost guarantee that by increasing the volume, you will decrease scavenging which will drop power.. As far as your engine "loving" a thick gasket between the reed and cylinder, I have no comment as there may be many other factors at play in your assessment. The beauty of the V-Force is that you are now using twice the number of petals to move the same amount of mixture through...therefor the petals move only half the distance making them last longer and offering a quicker response.