250 KX250 rebuild (Maybe one of the sickest rebuilds you'll ever see.. haha)



In this rebuild project a 1996 KX250 was bought for $200, the only parts that appeared to be missing were the silencer, some plastic body components, and the front brake reservoir.


As I began the tear-down i began realizing that many of the parts were discreetly missing. I first noticed that the Carburetor slide was missing after I took off the sub frame, air box, and carburetor. I had already known that the bike needed a new crank, crank bearings, and a top-end; and there was no telling about how bad the motor damage would truly be knowing that the bike sat outside in the rain, sleet, and hail throughout winter. Of course I knew I was going to have to strip all of the bike down to the frame and replace and grease every bearing and moving part, especially the swing-arm and shock bearings.

Unexpected Problems

After I began the dis-assembly and long restoration process for the bike I en-countered a major problem, the swing-arm was severely busted up and every bolt you could think on the entire rear end of the bike was stripped, rounded, or cross-threaded. So I then began the process of looking on eBay for a swing-arm in decent shape.

I observed the characteristics of the 1996 swing-arm and discovered that the 1994-1998 model KX125s and KX250s were very similar, so I ordered a very nice or at least decent shape 1998 KX125 swing-arm. Along with just being in better shape, the 1998 swing-arm offers better handling than the 1996 swing-arm. The 1996 swing-arm is about is about one inch shorter and about one inch less in width. Another advantage of using the 1998 swing-arm is that it is made out of aluminum so it is lighter, and the longer length provides better cornering and less front wheel pop in the straights.

Frame Repair

The frame was badly rusted and the sub-frame needed a new mount re-welded. First, for the main frame assembly I treated the rust and primed the frame. The main frame was then painted "alloy silver".

Motor Tear down

The top end only took about 5-minutes to tear down, I could tell I was definitely going to need a cylinder sleeve and piston. Once the top end was disassembled I removed the clutch cover and removed the clutch plates, clutch springs, clutch inner and outer basket, and clutch actuator rod. Next, the kick starter assembly was removed and the water pump was removed, good thing the water pump was removed because the impeller was froze. For the final dis-assembly part, which was splitting the cases, I used a Tusk Crank Case Splitter from Rockymountainatv.com. This made taking out the crank and transmission easy. Here are some pictures of the dis-assembly...





Motor Assembly

The cylinder needed a new sleeve or to be chromed by a shop such as U.S. Chrome. I realized that for slightly $30 more I could buy a very nice cylinder off of eBay with a new cylinder sleeve, a slightly used piston, a KIPS cover, and carbon fiber reeds; All of which I was going to buy anyways. With all the new tools I bought I was slightly out of my budget, which was why the project got put on hold for several weeks, thanks to finding great buys on eBay I was able to jump right back on track with this project!

First off, since the motor was already disassembled there was no delay to install parts. I installed some new All Balls Racing crank bearings, although All Balls Racing products are cheaper they are not cheaply made, and they have been proven in amateur racing. Next, the crank was installed using a Tusk Crank Case Installer tool, due to the way the threads are on the crank of older KX250's I had to buy a dye to use the tool. After the crank bearings and Crank were installed the transmission was installed. The bottom end of the motor also received some new shifter forks due to the severe beating it took from the last owner. Next, the crank cases were put together using the Tusk Racing Crank Installer again. Finally, the top-end was installed along with a new Athena gasket kit.

More Unexpected Problems

As I began to disassemble the rear wheel I realized that the rear hub was cracked, It's hard to believe how mistreated a bike can be, especially when you take into consideration that it was once a brand new bike of a proud owner.Due to the hub being cracked I decided to go ahead and buy some nice aftermarket wheels. I decided to go with RAD MFG. Econo Wheels because they offer a great price for the package and the only issues i've heard of them have been about the wheel spacers. Not to mention the offer a trick look, thanks to RAD MFG.'s in-house anodizing, so i went with a Lime colored hub and a Black rim with Silver spokes and nipples.

Trying to Finish the Project

I had a very nice 2004 KX125 loaded with ProCircuit goodies, but unfortunately I had to be willing to sacrifice one my bikes to finish the rebuild. So after about a one month break from the project, and after selling my 04' I decided I mind as well dump some more money into this bike and just keep it. Since I now had $2100 in my pocket I decided to get the rear shock spring, frame, and swingarm powdercoated matte black. I also had to buy some forks along the way since mine were corroded. I bought 3 sets of forks of ebay, all of which were damaged just as bad as mine. So I finally decided to start browsing on Craigslist, and I finally found a set of 96' kx250 forks two days later. Come to find out I also had to spend $35 on some tripple clamps because I later figured out I had a 96' frame and motor with 95' forks, which are 2mm.s smaller in fork tube diameter. So after I figured all of that out I began assembling the frame, I've also been waiting for some parts so I decided to make some brackets and trim so older plastics so I could use the newer style (03-05) style plastics. Here are some pictures...

Rad Mfg. Wheel

Powdercoated Parts

Assembly and Plastic Conversion


Just When I Thought I Was Almost Done Buying Parts!!!

My new plastics finally arrived, so I began making the adjustments to make them fit. I also ordered OEM levers, swingarm hardware for the chain slider, and new pistons for the front brake caliper. All of which was around $140. Later on I ordered some black side panels, which I found out are very hard to find for this year and model, and some wave disc rotors for front and rear. I also bought a new rear Dunlop tire from a local dirtbike shop. I was about to install the motor but I found a very small crack on the connecting rod, so now I must also buy a connecting rod or complete crank. It's kinda bad, yet good at the same time that I found the crack because it probably would have messed up my cylinder wall plating and new piston. Although it seems i'm back to square one I'm really not. Now that I have to save up some more money, since my parents put $1900 of my money savings Arrrgggghhhh!!! I mind as well spend about $35 at local shop to get the cylinder (The cylinder sleeve was beginning to wear.) bored out 1 mm. so I will know that the bike will be race ready and run good for years to come, along with buying a new crank assembly so the crank doesn't need to be balanced after the new connecting rod is installed. Here's some more pics...

The Final Assembly... (yep, the third complete assembly of the bike!)

After I recieved the parts I began re-assembling the motor. I installed a new crank-shaft assembly and Wiseco piston I also replaced the water pump impeller. After I assembled the motor I installed the rest of the electrical system and put the motor in the bike. Everything on the new subframe lined up perfectly, although at first I didn't think it did because the UFO side panels didn't fit. The rest of the bike went together fairly smooth except I spent several months ordering the rest of the 'odds-and-ends' when ever I had the money... Below are the final pictures of the bike and further down on the page is a complete parts list with the total cost. The only thing the bike is still lacking are some nice graphics...





All Done!!!!
Parts List

Used Parts

New airbox
Cylinder (replated)
Forks (newer and larger diameter)
Radiators (sprayed with paint remover to remove stock black paint)
98' electrical system with TPS sensor for carburetor
New Parts

94'-98' style rear fender, side number plates, and radiator shrouds made by UFO plastics
03'-07' style front fender and front number plate
Renthal handlebars
ProTaper pillow top grips
Anodized works connection brake covers and assorted hardware
Factory Effex seat cover
FMF Gnarly
FMF Powercore II
ProCircuit Linkage
UFO gas cap
Motohose colored hose kit
Tusk racing Chain
JT rear steel sprocket
JT front steel sprocket
Renthal Brake pads front and rear
Galfer brake lines
Cyrca Handguards
Off brand wide footpegs
Turner performance chaing guard and roller wheel (red)
Tusk Racing Wave rotors front and Rear
Acerbis chain slid plate (rubber)
Topar Racing billet clutch cover and case saver
MotionPro clutch and throttle cables
Wiseco piston and Crankshaft assembly
Koyo crank bearing and water pump impeller bearings
Rad MFG. Econo series Hubs (green)
Rad MFG. Rims (black)
Heavy duty spokes
Heavy duty tire tubes
Aluminum rim locks
Dunlop tires front and rear
And approximately $450 in specialized OEM hardware (bolts)
And the running total is... $4,327.73

I'm very sorry for the long delay in updates and slow progress, but unfortunately I ran into some family and money problems along the way. I also had to stop spending money on the bike for about 3 months because I had to purchase my own truck when my father bought my step-sister a BRAND new Volkswagen Jetta. Although my problems aren't your problems I just felt as though I should explain why the build took such a long time....
you can't get black #plates for it... Unless you order them directly... Plus i'm running acerbis panels because the have the rubber heat guards for the silencer... :thumb:
you can't get black #plates for it... Unless you order them directly... Plus i'm running acerbis panels because the have the rubber heat guards for the silencer... :thumb:

That sucks. Oh well dude its still an awesome bike.:thumb: