power valve

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#2
the difference is in the way they are controlled, i.e. a mechanical powervalve normally use a centrifugal governor to move the valve. an electric powervalve use a electric stepper motor to operate the powervalve.
 
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#5
right the cr250's have it, which some of the reviews said wasnt the best idea. and the 125s dont have it although I think some of them used to and they said when they switched back to mechanical it was more effective.
 
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#6
steve.emma said:
the difference is in the way they are controlled, i.e. a mechanical powervalve normally use a centrifugal governor to move the valve. an electric powervalve use a electric stepper motor to operate the powervalve.

so a mechanical one is opened through centripetal force than right?
 

Rich Rohrich

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#7
rmc_olderthandirt said:
What bikes have an electric one, and why?
Rod

When you control the valve electronically, you can tie it's movement into multiple events like load (usually via TPS), ignition advance, and rpm to give it a fairly sophisticated opening curve. The power could be made much more usable once you get it sorted out. With a mechanical only system it generally follows rpm, and opens the same time regardless of operating conditions. Better than no powervalve, but far from optimum.

I'm not sure that Honda ever achieved a useful advantage on the CRs, but I am sure that it was an avenue worth persuing.
 
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#8
supposedly they never did get their electonic powervalves fully sorted out from all the reveiws I have read they just dogg the CR's :| . What is an RC valve and what does it do? was that something else only honda was doing?
 
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#9
When you control the valve electronically, you can tie it's movement into multiple events like load (usually via TPS), ignition advance, and rpm to give it a fairly sophisticated opening curve. The power could be made much more usable once you get it sorted out. With a mechanical only system it generally follows rpm, and opens the same time regardless of operating conditions. Better than no powervalve, but far from optimum.

I'm not sure that Honda ever achieved a useful advantage on the CRs, but I am sure that it was an avenue worth persuing.
yep i agree with that. having a external powervalve actuator that is electronically controlled is a much better idea in terms of maintainence and performance, it also has fewer moving mechanical parts.
like Rich said its a pity honda didnt take it further..... i mean they could have made the control unit have diferent ignition timming and powervalve actuator "maps" that the rider could select by flipping switches on the ecu. or go all out and have an "on the fly" type handlebar switch to provide different power for different riding conditions. not quite EFI i know, but it would have been cool.
 
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#10
im just doing a bunch of research on the hondas. im a honda guy Im looking at getting a newer bike but I have heard the yz's are so much better or what not. but to me its kinda like trading sides but I think i might just do it. but i still want to keep it honda
 
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#11
HubertGarfunkleIII said:
supposedly they never did get their electonic powervalves fully sorted out from all the reveiws I have read they just dogg the CR's :| . What is an RC valve and what does it do? was that something else only honda was doing?

An RC valvle is just the name Honda gave their electronic power valve. They did get the valve fully sorted out. It is quite reliable, quite effective, and doesn't seem to give owners half the problems of mechanical valves. The thing holding the motors back is the porting, not the valves.
 
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#12
Fewer mechanical parts, but more electronics. Probably okay if the bike already has a lighting coil, rectifier, voltage regulator and battery.

Rod
 
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#13
76GMC1500 said:
An RC valvle is just the name Honda gave their electronic power valve. They did get the valve fully sorted out. It is quite reliable, quite effective, and doesn't seem to give owners half the problems of mechanical valves. The thing holding the motors back is the porting, not the valves.
can you elaborate on porting please :cool:
 
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#14
The motor was just average all around for 02 (the first year of the RC valve). It had a weak bottom end, a mediocre midrange, and a decent top end. Honda went away from the standard 3 exhaust port system (one main port and 2 sub-ports) back to the 2 port style from the late 1980's. They also went to a case reed design where the intake is on the crankcase instead of the side of the cylinder. Honda made a lot of changes and it just wasn't as developed as their previous cylinder.
 
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#15
the reason im getting so into depth with this is im looking at getting a new bike. i have made up my mind on getting a newer 125. i kinda want to stay on a honda, but from what i have read and heard the cr's sucked. their 2005 + models were better but still not all that great. while the yz is supposedly the best 125. so im just trying to see if I should go cr or yz. I have also read alot that if the cr had a better motor it would be the best. i wonder if there are any mods i could do to the cr to make it the best. or if i did those same mods to the yz would it be better.


http://www.motocrossactionmag.com/M...0&tier=3&nid=259ECC09E87541C48B80E6D53A3D3962


Q:HOW DOES THE CR125 HANDLE?



A: Write this down for posterity: If the 2006 Honda CR125 had a broad, easy-to-use and powerful engine, it would win every 125 shootout. This is a sweet machine. It feels light, goes where you aim it and doesn’t exhibit a single bad habit.



heres some reviews and shootouts between the 2.


http://www.dirtrider.com/tests/motocross/141_0502_2005_honda_cr125r_yamaha_yz125/index.html7


i thought this was interesting and it will be neat to see the next article on it. a cr144


http://www.dirtrider.com/tests/motocross/141_0605_2006_honda_cr144r_long_term_test/index.html
 
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