Author Topic: lowering the 125´s powerband  (Read 5752 times)

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Offline tschisi

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lowering the 125´s powerband
« on: May 11, 2013, 06:31:02 PM »
hi!

I use my 2004 kx125 mostly for enduro riding and on small cornery mx tracks.
I´m really satisfied with the bike, but it would be nice to lower the powerband a little bit.

I know that this will cut my high-rev power, but that´s ok.
I know that i could buy a 250 or a 4-stroke, but i already tried that.
I know that a 125 is a 125, but i don´t accept that.  :lol:

I´d like to do that by revocable changes, so porting is not an option for me.
Afaik there´s no such pipe as a gnarly for the 125, right?
Would reed spacers bring good results?
I guess more flywheel weight would be good?
Change in jetting? (I run stock jetting, but a 35 idle jet)

thx guys
2004 kx125
1990 kx500 (sold)

Offline KXDINO

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Re: lowering the 125´s powerband
« Reply #1 on: May 11, 2013, 11:47:02 PM »
Lower gearing is first on your list,than try carbon tech lt reeds ,low tension that is.may be boyesens do a set for that model as well,there other things as well but costly.

Offline KevinTwoStk

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Re: lowering the 125´s powerband
« Reply #2 on: May 14, 2013, 05:43:19 PM »
The V-Force reeds should help the low-end response. Double-check to make sure that the '03 V-Force reeds will also fit the '04. If they do, I would snap those up if I were you!

FMF's Shorty silencer can boost the low- and mid-range response.

You might also consider a Steahly flywheel weight. It won't change the power characteristics, but it will smooth out the power and make it easier to ride.

One more idea is to go up one tooth on the rear sprocket. The lower gearing will be an advantage in tight terrain.

Offline delirious_nomad

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Re: lowering the 125´s powerband
« Reply #3 on: May 15, 2013, 02:09:05 AM »
go to motion forward and look at 2 stroke packages.

I just got my sons YZ85 back from Eric Gorr. for $136 all gaskets and a new ring (all parts from him are 20% off too) shipped he reshaped the head and shaved the cylinder. wow it now has power right off the clutch and lost none of its mid or top end...

I think it is $100 + parts and shipping (you can choose your shipper) for 100cc and higher... I am a believer, my son rode yesterday after coming off his XR 100 and he loved it... no more hit!

not convinced by me? call him and talk to the man yourself. he will and can also port (he offers 3 packages) to make the power band how YOU WANT it... I'm a Gorr fan for sure!
« Last Edit: May 15, 2013, 02:29:01 AM by delirious_nomad »

Offline tschisi

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Re: lowering the 125´s powerband
« Reply #4 on: May 15, 2013, 10:49:45 PM »
I live in Europe, which takes me some of this opportunities.  :-(
I just saw that i run 13/50 gearing, so my next rear sprocket will sure be bigger...
I guess reed spacers would exceed the result of carbon reeds?!
What do you think about exhaust spacing?
Mayba adding copper ring?
2004 kx125
1990 kx500 (sold)

Offline motopunk

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Re: lowering the 125´s powerband
« Reply #5 on: May 16, 2013, 06:37:27 AM »
I live in Europe, which takes me some of this opportunities.  :-(
I just saw that i run 13/50 gearing, so my next rear sprocket will sure be bigger...
I guess reed spacers would exceed the result of carbon reeds?!
What do you think about exhaust spacing?
Mayba adding copper ring?

where in europe do you live?? i´m from germany...  8-)

exhaust spacing gives a little bit more torque at bottom end... at the moment i´m trying the same mods on my `83 kx250. this bike has a powerband like modern 125´s and i try to find a little bit more bottom end to mid-power.  exhaust spacing i know for sure, that it works,but the absolut maximum is 4mm,and make always sure, that the pipe fits properly to the cylinder.

 reedspacer is what i have to testing this weekend... ;O) i´ve made several spacers 5mm , 10mm and some selfmade gaskets with 1mm thickness. so i could space in 1mm-steps to find the optimum...
big 2 stroke bikes are weapons for real men, who don´t fear death or devil. ;O)
´83 kx250, ´87 kx250 (with 360 big bore), 87 kx500, ´93 kx500 sfc

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Offline tschisi

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Re: lowering the 125´s powerband
« Reply #6 on: May 16, 2013, 06:00:09 PM »
From Austria.

Please post the results of your tests!
I´d like to know if you win as much at the bottom as you lose at the top...
2004 kx125
1990 kx500 (sold)

Offline motopunk

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Re: lowering the 125´s powerband
« Reply #7 on: May 16, 2013, 07:08:21 PM »
From Austria.

Please post the results of your tests!
I´d like to know if you win as much at the bottom as you lose at the top...



hello austrian neighbor... :-) i live in northeast of germany ...
 and i´m excited how it will work on the 250 .. i have no dyno, so i can only speak of my feelings while riding...  :wink:
big 2 stroke bikes are weapons for real men, who don´t fear death or devil. ;O)
´83 kx250, ´87 kx250 (with 360 big bore), 87 kx500, ´93 kx500 sfc

---  www.der-motopunk.de.tl  ---

Offline motopunk

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Re: lowering the 125´s powerband
« Reply #8 on: May 17, 2013, 09:04:19 AM »
i installed the 10mm-reed spacer and a 4mm exhaust-spacer to my ´83-250 and first soundcheck says: ...whooohoo... it sounds a little bit diferent and stronger from bottom to mid... more i can say after short testride tomorrow...  :mrgreen:

i will post it in this topic: http://www.kxriders.com/forums/index.php/topic,1737.new.html#new
 

« Last Edit: May 17, 2013, 09:51:51 AM by motopunk »
big 2 stroke bikes are weapons for real men, who don´t fear death or devil. ;O)
´83 kx250, ´87 kx250 (with 360 big bore), 87 kx500, ´93 kx500 sfc

---  www.der-motopunk.de.tl  ---