First Build post here. Love buying, going through, riding, and then selling bikes. But this is the first that I’ve fully framed and touched every part on, plus it’s a 500, and I won’t be selling it. So I thought I’d share.
Picked up a 2002 KX500 back in April. Traded straight up for a 2003 CR250. Looked like a decent deal at first - typical wear and tear of a desert / trail bike, but nothing I wasn’t willing to work on myself. I wanted to replicate the ‘93 model, since ‘93 was the last year of the 500 nationals.
First pics once I got it in the garage. Not bad from 5 feet away. Whooped chain and sprockets, blown shock, ripped seat cover, tired plastics, and the obligatory mismatched farmers bolts.
The top clamp appeared to be off a late model Honda and didn’t properly fit the steering stem. I measured .135” of play between clamp and stem. Yikes. Need to hunt down the correct one.
Tore it to the frame. Everything was in pretty alright shape - no excessive wear or egging-out, just lots of grime. Detail cleaned every part - I think I should buy contact cleaner by the case. (Or just finally get a parts washer). All the finish was great under the grime, so no vapor blasting on this one.
Found that the late 90s KX250s share the same offset top clamps, so I bought one and machined a bushing and washer to make it work.
Carb cleaned, rejetted to Team Green Specs to start with. 170 main, 55 pilot, N89D needle @ clip 3. It’ll be pretty fat to start, we will see where we end up.
EVO MX Gripper ‘93 seat and ‘93 shrouds. Cut the yellow backgrounds and numbers myself. Found repro swingarm decals on eBay.
AEO Rebuilt and Resprung the Suspension. Parts laid out and ready for assembly
Frame was gussetted with a JT Engine Works gusset kit, then powder coated with Prismatic Powders’ Kiwi Green - little lighter than the OE color, great match for the plastics, close to the Team Green color.
Tore it open hoping to just do a piston. Looks like it’s sleeved, still on the stock bore.
This is the piston I pulled out of it.
Unreal. Not only was it making good compression and running like this, but with the carbon patterning, it was running like this for awhile! It had evidently spat that piston chunk out almost immediately, as there’s a small indent in the head where it hit initially, and nothing else. Cylinder had a little light, superficial scoring. These 1/2 liter 2 strokes are tough. Sent the cylinder and head to Eric Gorr for honing and porting. Wössner piston to match the stock bore.
Stock crank checked out beautifully, .016” of lateral rod play. Threw an EBC Dirt Racer Clutch Kit in it, slapped the clutch cover back on, and hoped to call it a day in the motor department. Then I got all excited, pulled the flywheel cover to check the ignition side, and…. Lots of flywheel movement. Great. Time for main bearings.
Split the cases, and the bearing came out with the crank. Looks like the bearing race was egged out in the case. Only a few thousandths oversized, but looks like case work at this point. I called Tom Morgan, he said that’s an easy fix and has oversized bearings that work, so the whole thing went off to him.
Coming together.
Finished roller. Pretty much everything is new, from cables to a complete hardware set and everything in between. Just waiting on the motor. Tom says February.
Since the photos, I found an original Renthal purple bar pad, and the correct KX500 top clamp. Still would like to get a DPR cone pipe, steel-braided brake lines, and an oversize front rotor before the motor is back.
I ended up picked up a low time 2000 KX500 as well, and will end up swapping the cylinders, putting the Nikasil’d jug on the 2002 for a full TMR engine build, not just an bottom end assembly. The Gorr ported cylinder will go on the 2000.
Will post updates as they’re available.
The Shop
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Luxon 4-Post Bar Mounts
$189.95 - $239.95
Get some 1/8 plastic T fittings and turn the carb into the loop design to help eliminate any hesitations from fuel vacuum
https://www.ebay.com/itm/294337792453?hash=item4487e649c5:g:XWkAAOSw2xR…
Pit Row
Wheels done
Forks are coming back today, ended up throwing 0.48kg springs in after riding the 2000 with the god awful 0.40’s. I threw the .44s that were in the ‘02 in the 2000 to match the 5.6 shock, will be nice for General Purpose / Off-road / Light MX duty.
The 2002 with the 0.48kg forks and the 5.8kg shock will be Moto duty only.
Galfer Lines and Rotors, plus a rebuilt front master cylinder and new wheels from Faster USA (Thanks a bunch Colin!). Not much left to do… just wait it out - the worst part!
Few More Angles
The 2000 got a new tank, seat covers, and numbers this week.
Motor build is on the way, and the 2000 is for sale if anyone is interested.
Quick update.
Motor is finished and shipping Monday. Hoping to update this thread next week with a successful conclusion to this build.
The 2000 is sold, with cash in hand for the CR500 I’m working through now. Hopefully that is done in the next month as well.
Mmmmm boy. Tasty treat from the UPS man.
Completed this morning. I really couldn’t be happier. Only hiccup was the pipe, I did not have the patience to pull the right side radiator to mount it. I may try at a later date, but the old PC made my favorite power, so we’re keeping it. Thanks all for following, and I’ll post a ride report here in the future at some point.
Quick family photo of the disgruntled stepbrothers
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