SpruceItUp wrote: 04:21 pm Mar 17 2026
I have RAD valve on my CR125 and it works great. It has quite the quality feel to it, especially because it is made of aluminum and not plastic like the VF3 on my KDX.
Performance wise I have no clue as they're on two different bikes, but I may pick up a RAD valve for my KDX. It is a really well built product. And the fact that the intake manifold is all aluminum and the boot on it is easy to find makes it worth it.
Chuck, you say the RAD valve behaves differently than the VF3, in what way does it do so that makes you like it?
Thanks
The RAD Valve is obviously the better design/build quality, with a generically replaceable coupling to connect the carburetor, instead of the OEM molded intake manifold boot.
The VForce has a quicker throttle response on the low end, but the RAD Valve has power gains everywhere else that the VForce3 does, and seems to smooth out the hit when the power valve opens a bit better, although this could be due to differences in atomization through the higher velocity through it.
Apparently the rad valve with the upgraded carbon fiber reeds improves the response on the low end exactly the same as the V-Force3, according to another forum member SS109 .
The RAD Valve's reed placement angle is a bit greater, causing the reeds to have to bend further, although durability of the reeds seems to be a non-issue. The VForce3 places the reeds at a more relaxed angle so that they do not have to open as far, and they have a larger reed area.
There have been a few complaints of people saying that the plastic VForce reed cages are able to be easily distorted and sometimes show up new from the factory with a slight distortion so that the reeds do not seem to seat fully closed on them.
I'm very likely picking up another RAD Valve from a member here, but also later this year, would like to pick up a new Moto Tassinari VForce4 reed cage to compare and try out.
In the past, it seems the VForce3 performance has been preferred in the KDX community, but with the carbon fiber reed petal upgrade, perhaps this was a non-issue?
EDIT - apparently Ron Black was saying that the VForce or stock reed setup using the stock type full intake manifold boot is better for the carburetors, as it dampens engine vibrations more due to having a greater length of rubber between the engine and the carb, and the needle jet and jet needle in particular will experience more wear with use due to the engine vibrations. Another forum member seemed to interpret this as the RAD Valve's coupling style will wear out the slide faster, but with the slide being covered in premix and being a snug fit in the bore vs an open orifice and a full circle tapered needle loosely blocking the orifice at varying throttle positions, this obviously is going to be the primary focus of the wear concerns. I feel this is not going to be as much of an issue on Lectron carbs, Lectron Billetron Pro Series carbs, and the new SmartCarb SC3 34mm metering rod carbs, as they aren't a fully tapered needle - their metering rods only are tapered with a flat bevel on the backsides, and therefore will remain in roughly 50%+/- contact with the receiver portion of the carb body instead of loosely plugging the metering orifice.[/I}
. Lot of work and money for a stupid reed valve system. Again, there is more to the story that is irrelevant to if someone has tried the vforce 4.
That's what we do here in Arizona. I like to be on the trail by 6am at the latest during the summer. I get out, hit it (25-40 miles), load up quickly, and home to the A/C!
