2012 Kawasaki KX 250F - Blown to Bits Corona Virus Rebuild
Article and Pictures by Jarrett Grantham

For the past couple of years I've been riding on ancient technology (2001 CR 250) so I decided to upgrade a little and do a project bike.  I bought this bike from a friend of mine that had started it but lost interest; basically a roller with no engine.  At the start of this project I was a little hesitant as I had never worked on 4-Strokes and all of that was basically foreign to me but I have the confidence in myself mechanically so I figured what the heck.  

This is basically the start of what I bought:

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- New Starcross tires

- New Front and Rear brakes from a parted out new 2018 KX 250f

- New Plastics

- New front & rear sprocket and a new Renthal Chain.

- New swingarm from a parted out new 2018 KX 250f.

- New Renthal Handlebars

- Front and Rear suspension rebuilt by EBR.


The Elephant in the Room (The Engine)

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As you can see, the engine was blown to bits and pieces and above is what I was dealing with.  I thought at a minimum I could reuse the bottom engine cases but that too was toast.  

I decided to go all in and buy new engine parts for anything that was trash; in hindsight I should have attempted to locate a running engine on Ebay or somewhere but I couldn't find one.  There was also the risk of that engine being bad as well.  

So, I bought the following

  • New OEM Cylinder Head by Fastheads with Del West valves, springs, seals, etc: $1229

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  • New OEM Intake Camshaft: $167
  • New OEM Timing Chain and Guides: $80
  • New Standard bore Cylinder Works Cylinder kit with Vertex Piston: $425

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  • New OEM Engine Cases: $464

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  • All New OEM lower end bearings and seals: $315 

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  • New ProX clutch plates and discs: $125

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  • New Tokyo Mods manual timing chain adjuster: $99

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  • No Toil Super-Flo Air Filter Kit: $38
  • Tusk Radiator Hose Kit - Blue: $50
  • New Tusk Front and Rear wheel bearings: $37
  • Tusk High Pressure Radiator Cap with temp gauge: $25
  • Tusk Wireless Hour Meter: $25
  • Factory Effex OEM Shroud and Tank Graphics 2012 OEM Style: $35
  • Tusk Folding Shift Lever: $20

Lessons Learned

  • Always buy a running bike; it will make it a lot easier when assembling.  This is especially important if you have never worked on that brand and model.
  • Buy OEM parts for things like engine bearings and seals.
  • In my case I should have bought a complete engine that was either rebuilt or an enigine that is nearly new pulled from a running bike.  I could have probably bought a 2016 and above engine and converted all the electrical stuff much cheaper than rebuilding the 2012 engine.
  • When putting in new lower end bearings the easiest way to do that is the freeze the bearings overnight or in dry ice and heat the engine cases in an oven to about 275 F.  They usually will pop right in but you have to be fairly quick about putting the bearings in.  Keep a few sockets and a light hammer available in case you have to lightly tap the outer races to get the bearings in.
  • Always buy new parts if you can; you will start second guessing your purchase if it's used.
  • Your going to need quite a few tools to get started; things like flywheel puller, Crankcase puller and Installer. 
  • Take your time and re-check everything you assemble; there are so many pieces that it never hurts to double check.

The Finished Project


The overall project took about 3 1/2 months (excuse the messy garage) but it gave me something to do while in lockdown due to the Corona 19 virus mess.


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