2003 KX125 Build

rrjr
Profile picture for user rrjr
Posts
1133
Joined
11/1/2012
Location
USA
rrjr
Edited Date/Time 10/18/2017 8:08pm
My son went from riding a 65 to a crf150r and then to a kx250f. He said he wanted a two stroke to ride because he never really rode one when he was on mini's.

I picked up a 2003 kx125 for him. The bike was in pretty good shape and had was supposed to have a Eric Gorr 144 kit on it with a fresh piston and rings.

Went out the first ride and it blew up. So I decided to update it a little.

Rebuilt the top end
Rad hubs with Excel rims
Pro Taper bars
Works Connection clutch perch, axle blocks, Holeshot device and brake master cylinder covers
270mm front rotor
Front brake caliper from 2013 kx250f
Showa sff forks that were revalved
22.5mm triple clamps
2013 kx250f front fender and number plate
Acerbis hand guards















|
Sidecar
Profile picture for user Sidecar
Posts
1727
Joined
1/29/2015
Location
GB
Sidecar 10/22/2016 2:20pm
10/22/2016 2:20pm
Nice looking bike, good job.
SeaClassExpert 10/23/2016 2:50pm
10/23/2016 2:50pm
Can you adopt me?

Looks awesome!
CarlinoJoeVideo
Profile picture for user CarlinoJoeVideo
Posts
7517
Joined
11/30/2013
Location
Portland/Los Angeles, CA, USA
CarlinoJoeVideo 10/23/2016 3:30pm
10/23/2016 3:30pm
I think I was looking at that bike on Craigslist. Bummer it blew but you did a good job with the update!
rrjr
Profile picture for user rrjr
Posts
1133
Joined
11/1/2012
Location
USA
rrjr 10/23/2016 5:33pm
10/23/2016 5:33pm
CarlinoJoeVideo wrote:
I think I was looking at that bike on Craigslist. Bummer it blew but you did a good job with the update!
Yeah my son was pretty bummed out. He did two 5 lap motos before it let go. The guy I bought it from was really cool. When I told him what happened he ended up sending me a new top end kit.

Now that I know all the 2013 KX250F parts work on it I'm going to tear it back down and powder coat the frame, clean everything and make it all nice.

The Shop

See All »
Kx125rider 10/23/2016 5:51pm
10/23/2016 5:51pm
Loooks awesome, theyre great bikes. That actually looks like an 04, the 03 forks were different.
rrjr
Profile picture for user rrjr
Posts
1133
Joined
11/1/2012
Location
USA
rrjr 10/23/2016 8:10pm
10/23/2016 8:10pm
Kx125rider wrote:
Loooks awesome, theyre great bikes. That actually looks like an 04, the 03 forks were different.
Those are Showa SFF forks from a 2013 KX250F
TKL965
Profile picture for user TKL965
Posts
151
Joined
5/5/2014
Location
AU
TKL965 10/23/2016 8:13pm
10/23/2016 8:13pm
Kx125rider wrote:
Loooks awesome, theyre great bikes. That actually looks like an 04, the 03 forks were different.
2003 because the pipe mounts to the sub frame.
He has also installed kxf front end.
HenryA
Profile picture for user HenryA
Posts
3784
Joined
12/29/2011
Location
Stockholm, SE
HenryA 10/23/2016 11:55pm
10/23/2016 11:55pm
Looks great! How does the fork perform? Was it bolt on complete with clamps?
ctbale
Profile picture for user ctbale
Posts
1103
Joined
1/4/2014
Location
Gustavus, AK, USA
ctbale 10/24/2016 3:30am
10/24/2016 3:30am
would you consider loaning it to bubba so he has a bike for A1 ? ha
Racer_Twentynine 10/24/2016 3:39am
10/24/2016 3:39am
That's an 04 or newer based on the shrouds and rear plates.
ternst12
Profile picture for user ternst12
Posts
95
Joined
6/24/2014
Location
Buffalo, NY, USA
ternst12 10/24/2016 3:59am
10/24/2016 3:59am
Racer_Twentynine wrote:
That's an 04 or newer based on the shrouds and rear plates.
2003 and up had the newest body style.
Racer_Twentynine 10/24/2016 4:02am
10/24/2016 4:02am
Racer_Twentynine wrote:
That's an 04 or newer based on the shrouds and rear plates.
ternst12 wrote:
2003 and up had the newest body style.
My bad brain fart. Happens when you get old.
Kx125rider 10/24/2016 4:16am
10/24/2016 4:16am
Kx125rider wrote:
Loooks awesome, theyre great bikes. That actually looks like an 04, the 03 forks were different.
rrjr wrote:
Those are Showa SFF forks from a 2013 KX250F
Ahhh, My bad.
rrjr
Profile picture for user rrjr
Posts
1133
Joined
11/1/2012
Location
USA
rrjr 10/24/2016 7:09pm
10/24/2016 7:09pm Edited Date/Time 10/24/2016 7:17pm
HenryA wrote:
Looks great! How does the fork perform? Was it bolt on complete with clamps?
The forks were revalved and set up for my son by Enzo when they were on his KX250F.They were perfect in every way on the 2013 With the KX125 being lighter they are a little stiff but it's nothing a little adjustment can't take care of.

Everything switched over from the 2013 to the 2003 perfectly. It all bolted right up. I was actually surprised how easy of a conversion it was. The wheels are also from the 2013 and they fit perfect also.

I tried using the 2003 triple clamps with the 2013 forks. The bottom clamp worked but the top clamp was too big for the diameter of the 2013's fork tube. So I just switched everything, Triple clamps. master cylinder. brake caliper, fender and front number plate.

Going from 25mm offset triple clamps from the 2003 to the 22.5mm offset from the 2013 makes the bike a little "twichy"
and it turns a little too good. I'm going to see if I can find some that have the offset somewhere in the middle.
Stevens35
Profile picture for user Stevens35
Posts
8
Joined
8/28/2016
Location
Fredericktown, MO, USA
Stevens35 2/4/2017 4:06am
2/4/2017 4:06am
Did you use the rear shock from the 13kxf an if so did it go right on or did you have to modify anything?
BobPA
Profile picture for user BobPA
Posts
8331
Joined
10/31/2013
Location
USA
BobPA 2/4/2017 5:38am
2/4/2017 5:38am
You can run the stock clamps if you have a shim made. I haven't personally done it, but have seen it done on the inter webs.
hillbilly
Profile picture for user hillbilly
Posts
9079
Joined
8/16/2006
Location
Afton, TN, USA
hillbilly 2/4/2017 7:21am
2/4/2017 7:21am
What "blew up" ,and was it poked and stroked to 144?

My buddy got PJ Larson's 125 in 05 and I did a 2mm stroke and 2mm bore on it. This makes the need for the head to be milled for piston to enter with the ring landing right at the top of the cylinder.

The power output was impressive.
rrjr
Profile picture for user rrjr
Posts
1133
Joined
11/1/2012
Location
USA
rrjr 2/16/2017 8:54pm
2/16/2017 8:54pm
hillbilly wrote:
What "blew up" ,and was it poked and stroked to 144? My buddy got PJ Larson's 125 in 05 and I did a 2mm stroke and...
What "blew up" ,and was it poked and stroked to 144?

My buddy got PJ Larson's 125 in 05 and I did a 2mm stroke and 2mm bore on it. This makes the need for the head to be milled for piston to enter with the ring landing right at the top of the cylinder.

The power output was impressive.
It just stuck a ring. No real damage. The guy I bought the bike from was really cool. He sent me a new piston kit and set of gaskets. It was indeed a true Eric Gorr 144 engine. It really rips. My Son is pretty big at 6'1" and 175# and he says it's just as fast as his 13 kx250f. Just a different kind of fast.
JMoore938
Profile picture for user JMoore938
Posts
20
Joined
10/16/2017
Location
Chesapeake, OH, USA
JMoore938 10/18/2017 8:08pm
10/18/2017 8:08pm
What all was required to install the 2013 kx250f triple clamps/forks?

Post a reply to: 2003 KX125 Build