A Little More Bottom-End From A 125

A 125'ER

Member
Dec 27, 2000
2
0
Hello fellow Dirt Riders! How can you get a bit more bottom end out of a '96 CR 125? How well does a flywheel weight work for helping this out? My bike has a Bill's pipe, PC silencer, and Boyesen Reeds. I recall something about using '99 power valves to increase bottom end. Has anyone tried this mod? What about a torque spacer between the intake and the intake manifold? Any coments will be appreciated. Thanks.

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'96 CR125
 

Yamadude

Member
Apr 13, 2000
2
0
125'er
from my understanding...
increasing the weight of the flywheel will provide you gains in rotaing mass momentum, which is typically used on 125s in enduro situations. The advantage here is the bike is less likely to stall due to the increased mass. The negative is that the bike is less RPM responsive to throttle inputs.
These attributes as related to low end pwr adavtages are negotiable. ....Less likely to stall however; slower to gain rpm.
I got my 125 to provide acceptable lowend through a FMF fatty, v-force reeds and alot of carb tweaking.
I have avoided Tourque spacers because I belived they would also inherently add a mid to high-end sacrifise in acceleration. Likewise, I thought adding a flywheel weight would make the bike sluggish in RPM explosiveness.
I did'nt want to take away from the attributes of 125 fun,...just feather the clutch on any low end bogs.

-J
00 Yam 125

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J.Olson
DFW, TX
Yamaha $1.25
 

125rider

Member
Nov 8, 2000
5
0
I have a 98 cr 125 that I rife on trails with. I have on it a pc pipe, fmf shorty silencer, v-force delta reeds, 12/52 gearing, and a 8 once flywheel weight With these mods I have found my bike to be an awesome trail bike with little or no trouble riding with the 250's.

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Racerdude

Member
May 24, 2000
148
0
Unless you have lots of money, or want to do irreversable (porting) you will have to make a sacrifice. The torqu spacer i used on my 97 YZ125 that I used to have, worked like a charm. You might also try going up 2-3 teeth on the rear sprocket. Jetting might also help. Good luck!

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Air is great, but they put knobbies on these tires for a reason!!

Tyler #28
When in doubt, WFO

'01 KX125
 

MikeT

~SPONSOR~
Jan 17, 2001
4,110
11
Racer.. Is a torque spacer something that goes between the reedblock and cylinder? What is it, and how much does it cost?

BTW I think you will get the most response from adding a tooth on the rear.

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[This message has been edited by MikeT (edited 04-16-2001).]
 

nikki

Moto Junkie
Apr 21, 2000
5,802
1
I've been trying to get some more bottom end out of my YZ 125 and this is what I have added:

1 tooth to the rear sprocket, Mossbarger torque spacer (MikeT - they cost around $25 and yes, they go between the reed cage and cylinder), Boyesen Pro-Series 2-stage carbon fiber reeds, and a PC shorty silencer (and have rejetted the bike and reset the carb float level).

These mods have helped some, but I still might try another tooth on the rear...

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'01 YZ 125 - #32
2000 D17 Women's Motocross Champion
Sponsors: DGY, MX-Tech, Bell, Smith, Works Connection, Boyesen, Twin Air, SoCal/DeCal Works, Morris Trailer Sales, and Skyway Trucking

[This message has been edited by nikki (edited 04-16-2001).]
 

A 125'ER

Member
Dec 27, 2000
2
0
Thanks for all of your input. The gearing I am running right now is 12/53. It is geared pretty low. For larger open roads, I run a 13 tooth countershaft sprocket. The v-force reeds you guys are talking about, are they just reeds that bolt to the stock reed block, or is it both the block and the reeds? How well does a RAD valve work? I am curious about the torque spacer aswell. Do you sacrafice any top-end power with one of these?
Thanks for your help.

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'96 CR125
 

Racerdude

Member
May 24, 2000
148
0
The V-Force is a block and reed combo. From everything I have heard, the v-force is better all around than the rad valve. the rad valve tends to add a lot of mid hit, and thats about it. I dont know about your situation, but on the v-force, some applications require that you trim your intake to make it fit.

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Air is great, but they put knobbies on these tires for a reason!!

Tyler #28
When in doubt, WFO

'01 KX125
 

Yamadude

Member
Apr 13, 2000
2
0
as far as torque spacers go...

I heard some complaints that the addition of this mod will make the 125 not want to rev as high. Maybe some of the people here could comment on that.

I like to comment on the V-force-2 reed cage. I've been throughly impressed with it. I felt that the addition did not require any jetting changes on my machine. I did have to make some air-screw adjustments.
In my case; the "high rpm" setting took away from the low-end (but had a huge hit in the high rpm range). Also, the "low RPM" setting (this is with the reed petal stop) did'nt add any low-end to my 125 (as opposed to the stock cage). The gains were either high end, or mid to high with the latter.

-J

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J.Olson
DFW, TX
Yamaha $1.25
 

Randy KX125

Member
Sep 6, 2000
10
0
I would just send it to Eric Gorr, tell him what you want and, voila..there you go. Also porting can be changed after it is done with epoxies. Eric can and will explain it all to you. I think his port job cost less that a V-force reed cage. Go to his web page and call him.

He did my KX125 and it hauls through the ENTIRE power band!

Good Luck,

Randy

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the Eel

~SPONSOR~
Sep 23, 2000
1,747
0
Randy - which powerband-type did Ericport it for ? Overall ? Or low-mid ?
 

marcusgunby

LIFETIME SPONSOR
Jan 9, 2000
6,450
2
The Crs do respond well to the cometic thin(0.3mm) base gasket which gives a nice boost to bottom end power.You will need to stack 2 head gaskets together to stop the comp getting too high-or go with one head gasket and run race fuel and get even more bottom end due to higher compression.
 
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