yzeater

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May 21, 2001
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ok. so i finally moved up from an xr100 to a cr 125. i have no idea how to ride this thing. the brakes actually work and it has more than 8 horsepower...soo, can you give me general suggestions? Thanks.
P.S. What is this i hear about a powerband?
 

CRGuy

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Nov 14, 2000
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The powerband is when the engine pick's up in power quickly and is right around the center of the RPM's. It's made by a small chamber that open's to increase cylinder volume.
CRG
 

Danman

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Nov 7, 2000
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You can get those powerbands in any color that you want at the honda shop :p Just kidding. :) I think you should listen to CRguys post unless you realy just want to go the nearest shop and ask for a red power band to match your plastic:p
 

CRGuy

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Nov 14, 2000
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Ewww a red one! I told my mommy to only pick up the black one's!:p
J/k Look at my first post. LOL
CRG
 

High Lord Gomer

Poked with Sticks
Sep 26, 1999
11,790
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Originally posted by CRGuy
The powerband is when the engine pick's up in power quickly and is right around the center of the RPM's. It's made by a small chamber that open's to increase cylinder volume.
CRG
PLEASE do not attempt to answer questions as an expert if you do not really know the answer!

If you plot horsepower and RPM on a graph, the "powerband" is the range of RPMs during which optimum power is made. It is used to describe a range of RPMs. It is not a physical object that can be touched.

On most 125s, it is fairly high in the RPM range.

The powervalve opening to effectively raise the exhaust port does not "make" a powerband. For a better understanding of all of this, I would suggest searching on: Powervalve, PV, and powerband in both the advanced tech and Engine Modification forums.
 

CRGuy

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Nov 14, 2000
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So what is that chamber for then? I know it has something to do with the powervalve. I didn't mean to make it seem like it was a physical object only the chamber is physical.
CRG :eek:
 

MoO_coW

Member
Jul 14, 2000
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The powervalves give 2 strokes more low-end power. It is basically a piece of metal that starts off covering part of the exhaust port to give you more low end, when the RPM's go up so do the powervalves until finally they are up all the way recessed inside of the cylinder.
 
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CRGuy

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Nov 14, 2000
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I just looked at my manual. I see the valve's and how the operate.
Ok now that's strait. Why would you put a thicker gasket for the RC vlave cover? It wouldn't do anything.
CRG
 

Reeko

Member
Aug 9, 1999
67
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I am not familiar (yet)with the Honda exhaust valves, but in general there are a couple of parts to the valve system.
One attempts to alter the effective compression by altering the exhaust port timing. These valves being closed results in a higher effective compression ratio and exhaust velocities (better bottom end power).
The other part attempts to effect the returning exhaust compression wave by opening what I think Eric refers to as a surge chamber (at least for the Kawi Kips system). I think that changing the volume of this chamber is what we are refering to with the larger PV covers.

I am probably not describing this correctly though.
 

High Lord Gomer

Poked with Sticks
Sep 26, 1999
11,790
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What do you mean by the "RC valve cover"?

If you mean the Reed Cage, a thicker gasket (or a spacer) would effectively enlarge the intact tract, but that's a whole different animal than the powervalve.

We better stop this in here before Wardy makes us move to Rich's or Eric's room. :scream:
 

CRGuy

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Nov 14, 2000
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Not the reed cage:silly: Honda call's there power valve's RC valve's. I don't know why.
Yea I think we should stop before we get moved. ;)
CRG
 

Reeko

Member
Aug 9, 1999
67
0
I just got my Red Rider magazine. Know I understand what he means by RC valves.

In the mag, they talk about the servo controlled power vavles. They refer to them as "RC style". I think they mean that they are the same as some of there sport race bikes, aren't Honda's racing 2 strokes models "RC" ?
 

MoO_coW

Member
Jul 14, 2000
486
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Yes but the 125's say they have RC style valves also. And last year they had RC style valves so it doesn't have anything to do with the new servo controlled powervalves.
"Honda’s RC-style exhaust valve features an NSR road-racing-inspired rotary-flap exhaust-valve design that provides a smooth transition between low-range and midrange engine speeds. Also, this year’s exhaust-valve flaps feature a 2.5mm hole for enhanced low-end response. The exhaust flange bore shape is now oval, improving midrange and top-end power as well."
 
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Jaybird

Apprentice Goon
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Mar 16, 2001
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Charlestown, IN
RC = Radio Controlled
I think this is what they reffered to. Servos are used to control remote mechanisms on radio controlled planes, boats, power valves, etc...:)
 

Jeff Gilbert

N. Texas SP
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Oct 20, 2000
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RC = Ricky Carmichael:p
 

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