A good friend of mine wanted me to post this topic. Is a Power valve 250 cylinder woth the cash. IF it's worth it and people seem to like the ones they got he will buy one. Just let me know your honest opinions please. Thanks in advance.

 

Only get a powervalved 250 if you are going to race in the 250 class. Otherwise, a 310 powervalve kit is the same price. I have heard they make a huge difference, and have a very broad powerband.

 

Brad,
I heard they were harder to tune?
ERIC

 

Eric, aren't you supposed to be working? Got to go riding (i'm off work today). Karl

 

Karl, I am, well sort of.
ERIC

 

A couple people in our race series have the powervavled cylinders. One is a CT powervavle and the other is the Duncan powervavled.

I have spoken with the CT powervalve owner and he seems to like it. I guess at first he was not that impressed, but once he got the pipe that came with it, the motor was a lot better.

From people that I have talked to, they seem to like the motor, but it does not sound like it is the ultimate thing. I have to replace my cylinder this winter and I have looked into this quite a bit. Most people that I have talked to seem to think that the powervalve for quads is not the best gain for the money spent.

I have decided to wait before purchasing the current powervalves out there. One big reason is the CR250 that is being released in 2002. It will have an electronic powervavle, rather than a mechanical one. Wonder if it will be able to bolt onto the TRX250r lower end?

 

I think that is a very valid point that Lasher brought up about next years CR having an electronic powervalve.

All of the factory powervalved motors have some sort of mechanical actuation that comes from the cases. My 2000 KX250 has a little arm that comes out of the cases and actuates the powervalve.

All of the aftermarket powervalves that I have seen rely on (I guess) crankcase pressure to move the powervalve between its two positions. I have seen conventional powervalves get so gummed up with carbon that they would not work. I would think that this condition would be even more likely when you use crankcase pressure to open them. I don't KNOW this for a fact, though.

 

Mike,
I noticed a while ago that you mentioned needing a new cylinder. If you are .080"/68mm over now there is still life left! I'm .090" over on my 89 and still have a few more overbores left. The only thing you need to do is run the 86 piston and a spacer plate.
ERIC

 

Retro - I know about the spacer plate and using the 86 style piston. But the idea is not that appealing to me. While I do not have any knowledge of any drawbacks to doing this, I just don’t like the idea. Don’t know why, maybe because I have an 89 and I feel like I would be going backwards?

I need a new pipe as well, the FMF that came with the quad had a large dent in it. I purchased a PT pipe, had it ceramic coated then when testing it out, it blew off the motor and put a nice hole in brand new pipe. ($280 down the tubes in 5 minutes) Since I am looking for a pipe, I wanted to get a complete system from one manufacturer. I don’t know, just call me stubborn, like everyone else…

As for the current powervalves, they are actuated by pressure, not mechanical like the bikes. As for gumming up, I have not heard, nor asked, the riders in the series. But I have heard that the powervalve should be cleaned after every race and adjusted for each track. I talked to some one at Duncan Racing about a month ago to get prices and info. He stated that the regular cylinder would run about $1000 and the powervavle would run about $1800. When asked if the powervalve was worth the extra $800, he replied yes. Sales pitch? Not sure, but everyone I talked to stated that the powervalve will not necessarily offer MORE power just spread it over a broader range.

I asked ESR if they had a powervalve cylinder or planned to offer one. There reply was…

“We don't build a powervalve cylinder because, in our opinion, the technology to build one correctly isn't available, yet (check out the new electronically controlled powervalve set-ups on the 2002 CR250's). The powervalve cylinders available at current time leave a lot to be desired. When there is a DEFINATE advantage (that's not cost prohibative) to running a powervalve cylinder, we will be on top of it!”

Still not sure on who will get my business for next year. Or even if the powervalve will be an option. But with the electronic powervalve coming out…

Let me ask this… is the current (mechanical) CR250 a direct bolt on to the trx lower end? I have heard that FTZ sells these cylinders and just plugs up the powervalve. Wouldn’t that be great if it was that easy..

 

Well then Mike,
I'll buy that useless cylinder from you cheap? You can get a brand new one for $212 from Midwest Action Cycle in WI.
ERIC