I went all in on an overpriced Marketplace find today. It's a '90 KX125, the first generation with perimeter frame and conventional (41mm) forks.
Seller had it labeled as a 2001 but it was clear what year it really was from the pics. He said it has been sitting for a long while.
It started right up and shifted through all the gears without a hitch. It runs extremely rich, which could be old fuel, carb tuning or crank seals.. or more likely a combination of the three.
The first thing I do when I get a bike is crawl underneath and inspect the frame rails and lower side crank cases. I'm looking for wear as well as previous welds/epoxy fixes to the cases. I was surprised to see that the rails had very little wear considering its age, and relieved that there were no case cracks/repairs, and no evidence of orange RTV.
The frame spars and subframe also looked remarkable with relatively little wear on each side. Pretty sure this is the original paint as this scuff shows the black primer underneath that Kawasaki used.
The other thing that is often broken is the clutch cable stay in front of the clutch arm. It's intact.
The OEM countershaft guard and cover are still on the bike which was a surprise. The cases in this area are also intact.
The shock still holds charge, but it probably needs rebuilding at some point due to age.
The plan right now is to do a mostly cosmetic freshening up with
- New plastic (wish I had a set of TUF Racing's pink plastic to put on this bike)
- OEM graphics
- OEM seat cover
- Handlebars, cables and controls
- Tires/tubes
- Piston/rings
- Turbine Core muffler for woods
The hot ticket in the early 90's was to run '89 KX forks in place of the undersized USD units that came on the bike. So, I will source a set of clamps and forks and run conventionals on this bike. I also have some nicer '91 fork tubes with the blue anodized uppers I could run, but i hear the 46mm conventions were much much better.
As for the engine, I want to a minimum pull the cylinder and inspect the cylinder lining and power valves for wear/damage. I feel I should also go ahead and split the cases and replace the crank seals.
All in all, it is in okay shape considering the absolute scrap heaps I've looked at on marketplace of late. The seller wanted 1500 but I at least got him down to 1300. I still feel like I overpaid by several hundred dollars. It was one of the better machines I looked at in recent weeks so I decided to go for it.
Updates to follow as I work more on the bike 🫡
Any tips/suggestions for cleaning the decades old glue goo from the tank?
Same for removing the swingarm sticker and its vulcanized residue?
You should add an intake boot to your list
Have a Boyesen RAD11 on the way
Nice find. A freind of mine bought one brand new in 90', and he did well on it. The bike had a lot of mid and up power, but not much down low. It won the MXA shootout that year over the CR.
1990 KX125 review from Tony Blazier
The Shop
Luxon 4-Post Bar Mounts
$189.95 - $239.95
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Dirt Bike ranked it last that same year 😅
Lucked up on some nice NOS '90 KX125 shrouds with graphics already installed, this was the last set left:
I remember freaking out when a buddy had one of these. They looked so rad at the time.
Yeah that frame set up was wild bak then!
I guess I don't mind an engine rebuild I kind of expected it, but seeing this is a little bit of a gut punch. Cases are a little tricky to weld on especially when they have had oil and grease seep into the pores over the years
Why do people do this
I've had this happen on a bike or two that i've owned in the past. One bike was brand new and it threw a chain and busted that mount off. I rode it for probably 2 years like that before i had it welded back on. So not the end of the world.
Firestarter fluid (don't know the proper word in english) usually is a good glue remover
Can I get some tips on starting to clean the counter shaft sprocket guard that is broken off?
There's 35 years of grease and funk that has seeped into the cast aluminum. The more clean that is before it is TIG welding the better
Should I be using some heat along with a degreaser?
I don't remember anyone ever swapping the inverted fork for the 89's. I would go for a set of like later model forks. Like the 91 or 92 kawie had better inverted fork action. Compared to the other brands then.
I saw this in your first post when you said "cases intact"
I thought well... Kind of...
I would try goo gone and test in a small area first.
WD-40 and some heat works well, too. Like hairdryer heat, not blowtorch.
Pit Row
That broken case piece is no big deal, you have the broke piece…after seeing that airboot full of dirt, you knew a case splitting was in order….. Bike looks relatively low hr….I bought a super clean low hr 90 250 a few years back…got really lucky just needed some minor cosmetics and a good cleaning & greasing. I have also bought a few bikes that had the airboot look like yours… I remove all air filters before buying now😂 look forward to seeing your progress
Pulled top end apart tonight. Grit from air filter takes out the first smallest bearing it can find which is the wrist pin bearing. Crank will have to be rebuilt.
The powervalves are in tact though I do see some minor wear on the gear teeth. A guy in Europe makes new OEM style reproduction powervalves, may go in on them. He's been messing around with hard anodizing so I'm curious to see if that's an option when I order.
Previous previous owner recently installed a new Wiseco 589M05600 piston in this one.
Head looks fine, no prior wrist pin explodey damage.
Cylinder has some wear, expected after seeing the dirt in the air boot. A little bit of nikasil plating damage.. will probably need replating at least. It's still on stock bore.
Elsewhere on the bike, I was surprised to find that the shock linkage bearings are very tight.. no play at all when I pull up on the swingarm. That's almost a garuntee with most of these older bikes in this kind of condition.
Going back on my earlier thought about frame.. I think it has been painted at some point. The VIN numbers arne't filled in but have some material in them. Frame looks usable as is with some elbow grease.
Looks like it was mostly trail ridden or on the street by the look of the tires. Not much maintenance. Good for the chassis,... bad for the motor lol
Kawasaki paints swing arms silver. Are you sure the black is not primer under the silver?
And it’s brutal to remove.
I like your style.
I've had some 1991 KX 250 forks in my garage forever. So I decided on a whim to get some triple clamps off eBay and will try running the 91 forks on my '90 KX125.
I still think the 89 46 mm conventionals are probably better forks but, I like the look of upside down forks and the blue anodized uppers are pretty cool
In we go
I couldn't find your post again about the con rod but vintco listed this for the rod. Stating it was also for the 95+ kdx200. Funny the parts diagram for the kx125 doesn't list the rod separately. But the kdx200 one does and it comes up available oem for like $93.
Shipped off crank to Millennium for rebuild and balance. Asked them to use Wossner or Pro-X con rod.
Waiting on a Wiseco piston kit to arrive, got a NOS for $120. They are selling for $180 new today. I remember paying $80 for them when I was younger. Rebuilding bikes is not for the faint of heart, especially not in this crazy economy. Millennium wants $400 for replating. PowerSeal is around $300.
Need to finish pulling bearings from the centercases, then bring them to a vapor blasting guy over in Atlanta. Will also bring over my swingarm, triple clamps, and a few other aluminum tidbits. He says the airboxes and boots look great after vapor blasting so I may do that too.
Those are my short-term to do items.
Also on my list of stuff to work on are the front forks. Need to pull them down and rebuild with new bushings and seals. Would love to put gold valves in them but the math is already stacked against me with this project. I should probably at least get correct rate springs in it so it's at least rideable.
Need to get the shock dropped off at A1 in Atlanta for a rebuild and bump stop install, and probably correct spring rate.
Gotta get a few spokes replaced in the rear wheel. Nobody makes wheels for this generation KX, so that's not an option.
Why does this feel like its turning into a maximum rebuild? 🙃
Drain plug gasket: GASKET,10.5X16X1 92065-058
Crankcase right (outer) BEARING-BALL 92045-1209 (crank main)
Crankcase right (outer) SEAL-OIL 92049-1301
Crankcase right (outer) BEARING-BALL,#6303C3 601B6303
Crankcase right (outer) BEARING-BALL 92045-1497 (small one)
Crankcase right (outer) BEARING-BALL 92045-1304 (small one)
Crankcase right (inner) BEARING-BALL,#6905 92045-036
Crankcase right (inner) BEARING-BALL,#6202C3 601B6202
Crankcase left (inner) BEARING-BALL 92045-1209 (crank main)
Crankcase left (outer) SEAL-OIL 92049-1300
Crankcase left (inner) BEARING-BALL,#6202C3 601B6202
Crankcase left (inner) BEARING-BALL 92045-1252 (held on by two retainers)
Crankcase left (outer) SEAL-OIL,SC25376 92050-013 (output shaft/countershaft sprocket seal)
Crankcase left (outer) SEAL-OIL,TB13225.5 92051-005 (shift shaft seal)
Powervalve governor rod o-ring: RING-O,14.5X1.5 92055-1399
Powervalve top double o-ring: RING-O 92055-1439
Powervalve top o-ring: O RING,15MM 670B2015
Powervalve governer rod from case, orign: SEAL-OIL,SDO8144 92049-1207
Water pump gasket: GASKET,PUMP COVER 11009-1936
Water pump elbow gasket: GASKET,ELBOW 11009-1935
Water pump outer bearing: BEARING-BALL 92045-1497
Water pump inner seal: SEAL-OIL,MHSD8X18X10J-1 92049-1366
Clutch cover arm seal: SEAL-OIL,AG0353-F0 92049-1262
Kickstart seal: SEAL-OIL,SB16244 92049-002
exhaust silencer baffle o-ring: RING-O,BAFFLE PIPE 92055-1461
transmission input shaft snap ring: RING-SNAP 92033-1231 (3 total)
transmission output shaft snap ring: RING-SNAP,20MM 92033-1258 (3 total)
countershaft output shaft: RING-O,17.5X1.5 92055-022
Planning to run a bare aluminum swingarm. Hope the vapor blaster is able to get all the old paint/primer off
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