2004 KX125 Build

MXBen711
Posts
249
Joined
2/1/2018
Location
GB
Edited Date/Time 2/22/2020 3:35pm
I bought this little beauty a few months ago, and ive been riding it a little always with the idea of making it something special when i can. I forgot how much old bikes can fall apart, especially when they have been stood for years.




It was a field bike, and had been put away dirty so has some parts that need some love. I replaced the fuel pipe, cleaned the carb, put my bars and risers on, threw a piston in and it was pretty sweet. Tried a v force which was real good, and JD sent me an ignition to try which was even better. Toyed between a resto but i love those builds that Primo is building over at PC with the 18 plastics so that is the plan.

Parts so far:

A kit forks/X Trig clamps
90% of a Ti Kit - need a swingarm pivot and linkage bolts
PC Works pipe and Ti 2 Silencer
JD Ignition w/ 2 maps
V force
18 OEM subframe/tank/airbox
GUTS Phantom seat foam/seat cover
270mm front disc
CRF front brake master cylinder/caliper
Braided steel brake lines
WC Clutch perch

Parts on the way:

PC Head/Cylinder - ill be matching the cases
Hybrid Ceramic bearings
All linkage/suspension bearings
Machined down stock hubs

Coatings:

Alu Silver powder coated frame
Anodised crank cases/outer clutch/water pump
Anodised brake carriers/various parts
Cerakote brake calipers/master cylinders

I will be trying to document everything as well as i can but when parts arrive and things get sorted i usually just want to throw them on! Will be a total nut and bolt rebuild, and ill do my best to spare no expense. I have been thinking about a lectron carb, anyone have any opinions on those?

Excuse the workshop, its still under construction. Ill be sorting that out while the frame is at the coaters







2
|
10/10/2018 12:10pm
Sweet build!
Where did you get the 18 subframe etc? Can only find new ones here..

/ Christopher
MXBen711
Posts
249
Joined
2/1/2018
Location
GB
10/10/2018 1:11pm
Wangstedt wrote:
Sweet build!
Where did you get the 18 subframe etc? Can only find new ones here..

/ Christopher
I searched for months but could never find any used, finally just bought new. The items arent cheap but i want to build the best bike i can.

The Shop

MXBen711
Posts
249
Joined
2/1/2018
Location
GB
10/10/2018 1:17pm
Engine all stripped and separated into bags. This week i will be stripping every bearing and every seal from the cases, sending the transmission to the USA for some refinements and coatings and the top end to PC for porting.

While im waiting for that to be done ill be moving onto brakes and linkage


1
MXBen711
Posts
249
Joined
2/1/2018
Location
GB
12/4/2018 3:04pm
So a really busy few weeks has kept me away from getting too much done. Here’s the cases after they’re all stripped out. They’re really dirty and burned from the dirt that’s left on.

I’ve decided on cerakote for the crank cases and outer clutch/water pump. I’ve heard some horror stories of tolerances changing enough cause bearing issues and the amount I’m dropping into this it has to be perfect







The frame also came back from powder, and the clamps/forks came back from the coaters. I felt like I had to put them together just to make it look like I’d done something haha



Gearbox due back any day now, and currently working on the hybrid bearings. Once I have all the parts I’ll start with the rebuild
2
slamdmini
Posts
105
Joined
9/3/2006
Location
CA US
12/6/2018 6:45am
nice. looks like ur building basically the same bike as me, minus the a-kit. i too have been thinking about the lectron carb. for now i just rebuilt the stock one, but i may change later
MXBen711
Posts
249
Joined
2/1/2018
Location
GB
12/6/2018 7:01am
slamdmini wrote:
nice. looks like ur building basically the same bike as me, minus the a-kit. i too have been thinking about the lectron carb. for now i...
nice. looks like ur building basically the same bike as me, minus the a-kit. i too have been thinking about the lectron carb. for now i just rebuilt the stock one, but i may change later
The lectron is something that looks really cool, the ultimate goal would be to get a factory carb with no choke circuit!
slamdmini
Posts
105
Joined
9/3/2006
Location
CA US
12/6/2018 2:27pm
slamdmini wrote:
nice. looks like ur building basically the same bike as me, minus the a-kit. i too have been thinking about the lectron carb. for now i...
nice. looks like ur building basically the same bike as me, minus the a-kit. i too have been thinking about the lectron carb. for now i just rebuilt the stock one, but i may change later
MXBen711 wrote:
The lectron is something that looks really cool, the ultimate goal would be to get a factory carb with no choke circuit!
i agree the lectron looks bitchin
jg622
Posts
56
Joined
10/31/2017
Location
Grove City, OH US
12/7/2018 5:29am
Are you replacing all the bearing with the hybrid ceramic bearings? Id like to know where to get these from.
MXBen711
Posts
249
Joined
2/1/2018
Location
GB
12/7/2018 5:35am
jg622 wrote:
Are you replacing all the bearing with the hybrid ceramic bearings? Id like to know where to get these from.
They were really tough to find, and they arent cheap.

I have ended up going with a company over here in the UK called HB Bearings, and if they dont offer the size ready made they can re manufacture some to replace the ball bearings with ceramics.

Im still waiting on them so ill put some details up when i have them.

The only bearings i could find were main bearings and they were $110 each!

Heres a list of all bearing sizes in the bottom end

628 x 2
63/22 x 2
6204 x 1
SX04A81C x 1
SC03A53C x 2
6805JRZ x 1
608 x 1
MXBen711
Posts
249
Joined
2/1/2018
Location
GB
2/22/2020 1:31pm
Long time with no updates, but here is the bike as of today!

Everything has been dry fit to see how it fits, next is the disassemble and rebuild with everything as it should be.

There have been some challenges, foot pegs in particular!











6
DrewJett747
Posts
154
Joined
5/22/2018
Location
Belleville, IL US
2/24/2020 8:10pm
jg622 wrote:
Are you replacing all the bearing with the hybrid ceramic bearings? Id like to know where to get these from.
I’ve been told the World Wide Bearings Is great to work with. Let me know if you decide to buy from them. I would really like to try them out in my next build. I’m curious how much they cost and if it’s beneficial to only do your main bearings or if it’s a waste if you don’t do the entire motor. I’ve heard $500 for 4 bearings.


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