I had an idea

[Piney0]

Okay, 2002 and up CR250's had the electric powervalve.   My thought is Using the Servo motor from the CR to operate the powervalve in a TRX cylinder.  

CR's are gear driven, think something could be made to connect this to the TRX powervalve?

Making something like this is above my capabilities, so anyone who wants to give it a shot, please go ahead.

What do you guys think?

[Burns363R]

The biggest trick will be adapting it to work off of a signal so that it is in the right position at the right RPM.


The easiest thing would be to put the CR cylinder and everything on, and use it and the ignition from the CR.  But i think the main problem with the 02 and up CR's is that they are case reed design, so it really wouldnt work.  Now if they had a Servo driven Power valve on a cylinder reed design like our current setup.  Someone could adapt the cylinder to our bottom end.

[hontrx265r]

I brought this up last year to a couple engine builders and they did not think it was worth the effort for the gain that may be involved. It would need a more advanced ignition but its doable. I thought it would be even better to be able to map the p.v. characteristics so you could really dial in a particular engine and give it the most optimal port height at each rpm/tps.

[Piney0]

Good points.  What's frusterating is knowing the exact gains over each system would be real easy to tell if one was designed.    I'm sure I am not the only one who feels that the rotax style powervalves aren't that predictable in when they operate, and I can see a setup like this being more predictable.

I guess we would really need to map out the signal in order to know the potential gains.  It would be interesting to see if the throttle position sensor plays with the timing too.  If so, that makes another way that the PV signal might be able to be dialed in for our use.

I'm also surprised that the engine builders didn't think it was worth the effort, but I'm not an engine builder, so I don't know what crazy stuff goes on in their heads :rofl:

[mx250r91]

Wow I didn't think anybody else was interested in this, seems the trend with aftermarket cylinders has been towards non-powervalve for the most part.

I've actually been working on this for a while now not but not within almost a year now as there have been other priorities, projects, children etc. taking precious R&D time.

But here is what I have so far, I'm using an aftermarket programmable DC-CDI with integrated powervalve controller. This allows full customization of the ignition maps, PV maps, TPS input, rev limiter, power jet solenoid... you can even mount a switch on the bars to toggle different ignition/PV maps (think holeshot setting...) pretty cool stuff!

Wish I had more time to finish and test, hopefully someday I'll have a ride report.

[Piney0]

Wow!  This is cool.  On first look, it looks like an RZ YPVS servo motor, and a modified rotax powervalve.  I have an RD350 also, so I know a little about that system, and zeeltronics.  This is very cool.

Please keep us posted if / when you get further.

[Jerry Hall]

I think a programmable controller is the only way to properly control a power valve.

I do not like the pneumatic (rotax type) power valves.  They are not very repeatable and tend to close when you let up on the throttle.  A bog often occurs if you suddenly close the throttle and immediately snap the throttle back open when the engine is in the RPM range where the engine is on the pipe.  The pneumatic type valves tends to open a little late on a cold pipe and a little earlier when the pipe is saturated with heat.

The Zeeltronic units work really well. I have used them for years on road racers and custom projects. I just have not had anyone that had a Honda big bore that was willing to spend the money for the Zell controller, stepper or servo actuator and the necessary hardware to make it work on the pneumatic type power valve. You are also going to need to spend half a day or so on the dyno mapping the ignition and power valve curves.