2003 CR 125 Vet Build

Teej317
Profile picture for user Teej317
Posts
888
Joined
4/30/2010
Location
Colstrip, MT US
Teej317

A few months ago, I picked up this cr 125 for $1000. I've always been a 4 stroke guy and have had a couple 250 two strokes in the past. I've tried a couple 125s in the past but never had one of my own. I'm 33 now with wife and kid, but still love to ride and race. I figured what the heck...lets do a fun 125 build.

My plan was to build something reliable and close to stock. A little disclaimer...I am on the heavier side for a 125 some would say (205 lbs). My normal bike is an 18 Rmz 450, so I wanted this 125 to change things up and have a "play bike." Here it is when I picked it up....

IMG 0893.jpg?VersionId=oO2qmK6PzsSHQmH1kKo

IMG 0894

 IMG 0895.jpg?VersionId=NmpmpL92Kk4VSaC6IOr70Sdkn4Yt

 

 IMG 0897.jpg?VersionId=SMVrU46BYmi

 IMG 0898.jpg?VersionId= l5iNrOSsapIsYY Qr

 

2
|
Teej317
Profile picture for user Teej317
Posts
888
Joined
4/30/2010
Location
Colstrip, MT US
Teej317 3/6/2023 9:05am
3/6/2023 9:05am Edited Date/Time 3/6/2023 9:14am

Teardown went pretty well with no surprises fortunately. The bike came with a PC platinum pipe and R304 shorty already on it, which was a win. Got everything torn down and off to cleaning. Full engine rebuild was done with a Wrench Rabbit rebuilt kit. Forks and shock were rebuilt with fresh fluids, bushings, and seals. I put a heavier spring on the rear from Race Tech to help carry my butt around the track.

IMG 0910

 IMG 0939.jpg?VersionId=dQ1xs5XDQoPAaZ.Tv

 IMG 0908.jpg?VersionId=Qgo96tCQJ4zMRNeOlpXqbRyfCe J

 IMG 0906

 

1
Teej317
Profile picture for user Teej317
Posts
888
Joined
4/30/2010
Location
Colstrip, MT US
Teej317 3/6/2023 9:08am
3/6/2023 9:08am

IMG 1097

 IMG 1098.jpg?VersionId=Lo7XXdHULXnI2C.0jc P

 IMG 1099.jpg?VersionId=3d

 IMG 1100

 IMG 1101

 

9
Teej317
Profile picture for user Teej317
Posts
888
Joined
4/30/2010
Location
Colstrip, MT US
Teej317 3/6/2023 9:11am
3/6/2023 9:11am

Big shout out to HM Designs for pulling this kit off. Bike runs great and getting the jetting dialed currently. I'm running Motul 800 with Sunoco 110/pump mix. I plan to drill holes in the airbox to help her breathe a bit more. I thought about doing the powervalve pin mod, but not sure if it's worth it? I do have a pipe spacer on the way to help give me a little more bottom end. Other than that, what you guys think?

Rickyisms 3/6/2023 9:24am
3/6/2023 9:24am

Nice build! That generation of Hondas are so much fun to ride and are very confidence inspiring chassis. Definitely down on power compared to other 125s, but I know a Truck driver on here who knows the hot setup for these things. 

5

The Shop

See All »
Teej317
Profile picture for user Teej317
Posts
888
Joined
4/30/2010
Location
Colstrip, MT US
Teej317 3/6/2023 10:09am
3/6/2023 10:09am
Rickyisms wrote:
Nice build! That generation of Hondas are so much fun to ride and are very confidence inspiring chassis. Definitely down on power compared to other 125s...

Nice build! That generation of Hondas are so much fun to ride and are very confidence inspiring chassis. Definitely down on power compared to other 125s, but I know a Truck driver on here who knows the hot setup for these things. 

Appreciate it! I'm not too interested in spending a bunch of money on porting and boring it out. Looking for small improvements that can be squeezed out of the stock setup. After a few heat cycles and driving it around the block, I can tell its gonna be a blast. It is pretty comical hopping from the 450 to this 125...there is absolutely no bottom end lol. But that's what makes it fun, right? I have some learning to do because I've never been one to use my clutch much. Totally different mindset needed on this 125 to keep it on the pipe.

profeshenal125 3/7/2023 10:16am
3/7/2023 10:16am

632BC516-2C41-4CD6-95DD-00324F4FF754Sharp bike the red plastic is So bright, what co ? I hv 2 04,s & a 05 now. I had another new 04 & 2 06,s stolen. 04 has its own yr air boot it’s dead on the bottom but hits harder in the mid. 05-07 air boot adds bottom to mid with more torque runs very clean to the top. Get the 05-07 air boot. V force runs good but no torque difference. Rad valve adds low & mid torque. Power flow alum cage adds low to mid a little torque & runs clean to the top . The cr125,s run snapper with a new coil, grind the mounts to raw alum. Pc shorty. I drilled 3 holes each side of air box a little improvement. Each part adds a little bit but still runs clean bottom to top. My practice 04 is snappy & runs So clean to the top Very fun to ride. It has a racers choice Wiseco piston, Very Good. Carbon fiber reeds stock cage. I changed cdi,s to a 5 hr 04 with a fmf with RV it runs like a 134 torque feeling but revs to the moon.  I like the 04 engine more than a 06. Even tho it’s probably the worst 125 to get on the pipe . It forces you to carry momentum the mid hit & pull is strong . I pulled 16 yr olds on 23 yz,s off corners into a up hill. 

 

2
1
profeshenal125 3/7/2023 10:49am
3/7/2023 10:49am

JM racing decked & ported with a diff carb taper bore. It added a long & strong mid range into the top end. It sounded really sick pulling threw the mid. You could short shift or rev it out. I then had a 2 mm stroker crank & 2 mm ovr bore done. In 2010 no doubt it would pull any mod 250f. About even on torque 23 but a stab of the clutch it hit 23 ft lbs Rt Now like it was charged from a transformer.  A blast to ride. 2nd engine is Tara Geiger,s replica LL championship engine spec with a bit more torque for my 171 lbs.  I hv not tested it yet, snowing here yet.  As far as pulling a 23 yz my 04 runs clean. The yz had a blurber b4 it hit, so easy pass. 

1
Teej317
Profile picture for user Teej317
Posts
888
Joined
4/30/2010
Location
Colstrip, MT US
Teej317 3/7/2023 12:01pm
3/7/2023 12:01pm
profeshenal125 wrote:
Sharp bike the red plastic is So bright, what co ? I hv 2 04,s & a 05 now. I had another new 04 & 2...

632BC516-2C41-4CD6-95DD-00324F4FF754Sharp bike the red plastic is So bright, what co ? I hv 2 04,s & a 05 now. I had another new 04 & 2 06,s stolen. 04 has its own yr air boot it’s dead on the bottom but hits harder in the mid. 05-07 air boot adds bottom to mid with more torque runs very clean to the top. Get the 05-07 air boot. V force runs good but no torque difference. Rad valve adds low & mid torque. Power flow alum cage adds low to mid a little torque & runs clean to the top . The cr125,s run snapper with a new coil, grind the mounts to raw alum. Pc shorty. I drilled 3 holes each side of air box a little improvement. Each part adds a little bit but still runs clean bottom to top. My practice 04 is snappy & runs So clean to the top Very fun to ride. It has a racers choice Wiseco piston, Very Good. Carbon fiber reeds stock cage. I changed cdi,s to a 5 hr 04 with a fmf with RV it runs like a 134 torque feeling but revs to the moon.  I like the 04 engine more than a 06. Even tho it’s probably the worst 125 to get on the pipe . It forces you to carry momentum the mid hit & pull is strong . I pulled 16 yr olds on 23 yz,s off corners into a up hill. 

 

Interesting stuff, thanks for the comment. The front plate and fender are off a '22 crf 450. I used Cameron Niemela's adaptor kit and the fitment is great. I'm going to start with punching a few holes in the airbox and take note of each little change. 

1
profeshenal125 3/7/2023 12:24pm
3/7/2023 12:24pm

3E27C3E4-B98A-4200-935E-7770512EF309.jpeg?VersionId=7GiFH9HYU7RnsslRfzVhxkYNS1qRwYou should b able to see where I drilled my holes in that pic. Power flow cage filter has a diff shape & it’s  a smaller filter.  I got in a standing position & moved around like I was riding. My legs didn’t cover the part of where I drilled my holes as much. 

 

1
johnk408
Profile picture for user johnk408
Posts
1085
Joined
1/20/2022
Location
Ft Mitchell, KY US
johnk408 3/8/2023 2:24pm
3/8/2023 2:24pm

Didn’t know there were $1000 125’s out there still. I looked all winter for a project and people still wanted $2500 for bikes even if they were in pieces.

2
Teej317
Profile picture for user Teej317
Posts
888
Joined
4/30/2010
Location
Colstrip, MT US
Teej317 3/8/2023 8:21pm
3/8/2023 8:21pm
johnk408 wrote:
Didn’t know there were $1000 125’s out there still. I looked all winter for a project and people still wanted $2500 for bikes even if they...

Didn’t know there were $1000 125’s out there still. I looked all winter for a project and people still wanted $2500 for bikes even if they were in pieces.

Sounds about right lol. I put a feeler out on a local Facebook group and a guy messaged me. Guess I got lucky. But yea they are out there. 

Teej317
Profile picture for user Teej317
Posts
888
Joined
4/30/2010
Location
Colstrip, MT US
Teej317 3/8/2023 8:30pm
3/8/2023 8:30pm

Got holes drilled and found these cheap vent inserts off Amazon.
A30F2AF4-BE13-4B77-BE0B-9E8D07B77822.jpeg?VersionId=3sJQM 7amdDTJBGZh33celhHNI

 

4
mjones7212
Profile picture for user mjones7212
Posts
164
Joined
8/5/2021
Location
Oildale, CA US
mjones7212 5/17/2023 7:44pm
5/17/2023 7:44pm Edited Date/Time 5/17/2023 7:45pm
johnk408 wrote:
Didn’t know there were $1000 125’s out there still. I looked all winter for a project and people still wanted $2500 for bikes even if they...

Didn’t know there were $1000 125’s out there still. I looked all winter for a project and people still wanted $2500 for bikes even if they were in pieces.

ive got a complete 04 cr125 that id sell for 1300 but im in california 

DylanVV21
Profile picture for user DylanVV21
Posts
41
Joined
8/17/2015
Location
Fowler, CA US
DylanVV21 5/24/2023 2:56pm
5/24/2023 2:56pm
mjones7212 wrote:

ive got a complete 04 cr125 that id sell for 1300 but im in california 

Shoot me a text, I may be interested..

559-301-7491

 

Also TJ, looking good!!

1

Post a reply to: 2003 CR 125 Vet Build