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2006 KX250F Rebuild
Posted: 03:01 pm Feb 21 2022
by Slick_Nick
I bought this bike in the summer of 2018 for $1800. It ran, but not well. Picked it up with the intention of having a new project. It sat in its roached condition in my garage for two years, until I decided that I wanted to get back into motocross. (I ended up buying this bike's twin, a 2007 model, in the fall of 2021, from the same guy I got this bike from.) It's rebuild it forthcoming.
The 2006 KX250F is, in my opinion, my "dream" motocross bike. When I first saw it released, I loved the black and green look, the smooth aluminum frame, the brown-gold triple clamps and engine covers. It was the first year of the aluminum frame for Kawasaki (their previous foray in 04-05 were the steel framed "kawazukis".)
With all that said, lets get into it. When I looked at the bike, it ran, but it popped, it backfired, it was super lean, but the engine itself had no knocks or anything, so I felt safe to assume that even though I intended to do a full rebuild, I wasn't in for any huge ticket items.
Here is the bike as I picked it up, and got it home for a wash off to see what we're dealing with.
Figured I'd hit it with the inspection camera. Lots of carbon, and looks like an aftermarket piston. The cylinder head is a different shade of weathered aluminum, perhaps it was replaced at one point?
Re: 2006 KX250F Rebuild
Posted: 03:06 pm Feb 21 2022
by Slick_Nick
Re: 2006 KX250F Rebuild
Posted: 03:16 pm Feb 21 2022
by Slick_Nick
Project bikes are always FULL of surprises. I really love (and i mean LOVE) how this bike looks stock, so months before this, I had already ordered a new to me (lightly used) stock seat, since I assumed this one had this gross cover on it. But wait... What's this we see underneath it? Half an hour later, and after pulling what felt like hundreds of staples, I was surprised to find, an almost mint condition stock seat cover still in place! There was a white streak on top, but that easily wiped off later on! What a score!
This exhaust is a full Pro Circuit Ti-4 Titanium system. Brand new, this exhaust was close to what I paid for the whole bike! More on refurbishing this exhaust later, don't worry, but for now enjoy the grossness.
With the wheels off, let's break them down and see what we've got. The front wheel was bent, both wheels were missing spokes, and the spokes that were left were so seized that many needed to be cut off! There were stripped rotor and sprocket bolts, but those were removed by welding on a fresh nut with the MIG.
These bearings sure look awesome!
Re: 2006 KX250F Rebuild
Posted: 03:21 pm Feb 21 2022
by Slick_Nick
Re: 2006 KX250F Rebuild
Posted: 03:27 pm Feb 21 2022
by Slick_Nick
Re: 2006 KX250F Rebuild
Posted: 03:35 pm Feb 21 2022
by Slick_Nick
Re: 2006 KX250F Rebuild
Posted: 03:41 pm Feb 21 2022
by Slick_Nick
Upon closer inspection of the piston, it looks like this one may have kissed the valves at one point. Maybe that's the reason for the new cylinder head?
Let's tear down the head so we can clean and inspect it.
Once the head was cleaned in the solvent tank and dried, I hit it with a super soft glass bead in my blast cabinet. This easily removes all carbon, but won't harm things like valve seats. Use care to blow out every tiny nook, cranny, oil passage, water jacket, with compressed air. Then, do it again. Then, do it some more, until not a single glass bead remains. Then, wash the head with soapy water, and repeat the last three steps again.
You absolutely CAN NOT lap titanium valves! I did, however, green them up, and double check that the contact patch was good.
Re: 2006 KX250F Rebuild
Posted: 03:47 pm Feb 21 2022
by Slick_Nick
Re: 2006 KX250F Rebuild
Posted: 03:49 pm Feb 21 2022
by Slick_Nick
Re: 2006 KX250F Rebuild
Posted: 03:54 pm Feb 21 2022
by Slick_Nick
Re: 2006 KX250F Rebuild
Posted: 04:03 pm Feb 21 2022
by Slick_Nick
With the frame back on the stand, we now have a clean, blank canvas to work with as we build this back up from a "bike in a box" to its former glory.
Since I already had a majority of my new parts in, I wanted to get everything cleaned, organized, and prepped as much as I could, so that the final assembly would happen quickly. Things were completely broken down, cleaned, bead blasted where required, inspected, replated, and organized so that they were ready to assemble and easily at hand. I find that breaking things down into "sub-assemblies" is a great way to stay organized and ahead of the game.
The petcocks on these bikes have a habit of collapsing. I was able to source a new one. I also sourced a used rear caliper mount, as this one was destroyed and unsafe. More on the assembly of these things later.
Re: 2006 KX250F Rebuild
Posted: 05:57 pm Feb 21 2022
by SS109
Dude, I love it! I have an '06 chassis that's been waiting forever to be converted in to an AF conversion. I actually pirated the forks to put on my KDX! Seeing how nice you got that frame and the other parts makes me want to get back to it but, sadly, I'm too deep in a lot of projects right now.
Keep the updates coming!
Re: 2006 KX250F Rebuild
Posted: 06:46 pm Feb 21 2022
by Slick_Nick
Re: 2006 KX250F Rebuild
Posted: 07:01 pm Feb 21 2022
by Slick_Nick
2006 models had silver rims and silver hubs, 2007 models had silver rims and bronze hubs, and 2008 had black rims and bronze hubs. While I paused for a minute, giving how well the stock '06 wheel hubs cleaned up in their bare aluminum state, I really liked the look of the wheels that the '07s came with, so they would be Cerakoted instead.
More parts blasted, and into a burnt bronze Cerakote. The color on the triple clamps is the same as the engine covers, it's just the interior lighting in my kitchen making them look so much lighter!
This bike came with Enzo suspension on it, I won't know until later on if it's set up for me or not, but I was able to see the stamp on the shock spring, and it was actually the correct one for my weight! Score! After it was blasted, I gave it a coat of Kawasaki green.
Before / during / after replating all of the hardware. In this case, it's the kickstart boss and stuff.
Re: 2006 KX250F Rebuild
Posted: 07:06 pm Feb 21 2022
by Slick_Nick
Re: 2006 KX250F Rebuild
Posted: 07:16 pm Feb 21 2022
by Slick_Nick
Re: 2006 KX250F Rebuild
Posted: 07:22 pm Feb 21 2022
by Slick_Nick
Freshly repacked and she's good as new! Well, not new, but considering this exhaust is now discontinued, it'll have to do!
I wasn't going to bother keeping that stock crank, I didn't know it's history, but lets check it anyway.
Rebuilding the crank with a fresh Pro-X rod kit and truing it up!
Got the runout to about half a thou, well within spec! She feels great!
I have no idea why the crank has that oil pattern or whatever like that, I've never seen that before, I tried everything under the sun to remove it, including a weekend soak in the solvent tank, thinner, lye, you name it. Oh well, give it cheetah power I suppose?
Re: 2006 KX250F Rebuild
Posted: 07:27 pm Feb 21 2022
by Slick_Nick
At this point, I basically had a bike in a box. All the hardware was cleaned, every last bolt was replated, parts were all ordered and all arrived, I had everything Cerakoted and refinished that needed it. New Kawasaki parts (where needed) were in hand, and most importantly, I had everything (except the forks) broken down, checked, and catalogued. I am pretty meticulous when it comes to how I do stuff, once I get going on a project, I hate having to wait on parts, or realizing that something was missing or broken. So, I cleared out a section of the shop, buit a makeshift table to temporarily keep things organized while I built, and I laid everything out to do one final comparison to my lists and make sure I had everything.
Behold, my exploded bike.
Re: 2006 KX250F Rebuild
Posted: 07:28 pm Feb 21 2022
by Slick_Nick
Re: 2006 KX250F Rebuild
Posted: 07:36 pm Feb 21 2022
by Slick_Nick