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BDX power valve delete vs STM power valve system

J
Mar 23, 2009
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It seems like me and all my buddies with AC's have had power valve/servo motor problems this year... everytime we go for a ride together someone has a problem that cuts the ride short so Ive been looking at ways to eliminate this problem.

The BDX power valve delete looks to be the cheapest, easiest, and most reliable fix but it appears to be just a fixed insert that doesnt open or close, and I cant wrap my head around how that can work good... it just seems like theres got to be a reason for the vakve to be there and theres got to be a reason for it to open and close at different points so I dont know how a fixed insert could take its place without a major loss of power somewhere in the curve. They have dyno sheets showing an actual power increase and it looks to be an increase across he entire curve could this actually be true does anyone have any experience with this, especially on a 1000 cat???

The STM system sounds like a decent option, taking the servo motor and cables out of the equation but I only know one person that has this and hes only got a couple short rides with it and his stupid sled is still throwing a intermittent ECU-18 code that really hurts performance and makes him really nervous never knowing when it might throw the code and bog down on him. He took it back to the mechanic that installed it and he said he went thru it with a fine tooth comb and called STM and worked with them they say the "chip" is good and wired right so it must be a faulty ECU causing the problems now... but since his sled hasnt ever worked right since the change and hes got very little seat time since the swap he doesnt know how well its working either

Sooo can anyone give me the pros and cons of either of these setups or any good or bad experiences???
 

m8magicandmystery

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there is no comparison..

STMs are in a different league....you maintain the original concept of the valves without the hassles..
 
J
Mar 23, 2009
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there is no comparison..

STMs are in a different league....you maintain the original concept of the valves without the hassles..

Yeah thats what I was thinking but BDX shows dyno sheets before and after and it appears that they increased the hp numbers across the entire curve... seemed to good to be true to me as well and I know that dyno numbers can be messed with I use to work for the company that manufactures the dyno that they used to run there testing. But I guess I was just hoping there was truth to it somehow since it seemed to be the easiest and cheapest fix, especially if there was an actual performance gain
 

m8magicandmystery

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the bdx valve delete for certain seemed a failure for the 800s as I haven't heard one good review..
I cannot say for certain about the 1000 but it seems that people wrote that they had a bad lower rpm performance with them .But I am not certain if it happened in all cases.
The power valve is great for low end and the STM keeps that advantage and as well you can adjust the opening rpm if you want with different springs on their new piston style
valve.

I know what you mean by wishing the bdx working ok,maybe someone will pipe in with good results for the 1000..??
 

Hardass

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I have the newer stem valves one has broke already with very few miles on it it broke tight where the threads start on the main shaft. Caring them tomorrow.
 

Rixster

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Oct 20, 2005
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It may help to understand the theory of the power valve and how it works.
Engineers found that a 2 stroke motor made more torque with an exhaust port lower in the cylinder. The trade off is that you make more horse power when the exhaust port is higher in the exhaust port. So, the fix. Bore a oval for the exhaust port, plug the top portion of it with a movable piece. At lower rpm, keep it closed with in turn lowers the exhaust port, at higher rpm open the valve which in turn raises the exhaust port. that way you get the best of both worlds. I have a hard time believing that you would GAIN any power with either of these setups. And i would tend to believe that with the fixed block off valve, you would see no change in the bottom end and lose hp on the top end.
 

kidwoo

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Yeah that locked in place BDX thing makes no sense to me at all.

I mean every modern 2stroke motor works on the same principle right? RAVE valves and whatever polaris calls them are the same thing aren't they? Just they (and STM) use springs and cat uses cables and a servo?
 
B
Nov 26, 2007
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Lake Tapps, Wa
On my 06 m7/8 I ended up having a bad servo so I just pinned my valves open and used the bypass chip so I'm open all the time. If you didn't know any better you may not notice but running twins I can tell that it's lacking a bit in the mid range. Once its on the pipe its a runner but in that 5500 to 6500 range it can be a little doggish.
 
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