At around 7000 miles the steering of my 250SL developed a nice notch at the straight ahead position, as they all do. This was annoying but the MOT man doesn't know what they are so it wasn't a terrible problem. However at 22500 miles the handling was turning weird so I decided to do something about it, not working thanks to the virus also meant I could take as long as I wanted. The first problem - how to keep the front end in the air without a centre stand? I ended up with this bizarre solution:
This was surprisingly stable but not as good as using a front headstock stand, so I decided to remove the forks with the stand in place (as this requires some pushing/pulling/twisting/swearing) and then switch over to the bolt-in-the-hole solution. This isn't exactly a guide because my bike doesn't have the front fairing like most do, but the next step is to take off the front end.
Transfer the bike to the special bolt-in-hole position (I usefully dropped mine when attempting it the first time, this job was slick from start to finish..!) and then take the yokes off. Hello loose-ball thrust bearings, my useless pitting friends..
I was surprised to find so much grease in these bearings but it's not as if it gave them a long life. The next stage is to knock the old races/cups out of the headstock, normally this isn't much of a problem with the little Kawasaki fought me all the way. The bottom cup in particular wedges itself at an angle and refused to come out, despite receiving some huge whacks.
It was no good as it was so time to break stuff.
The headstock was a little worse for wear after this procedure (!) but nothing a few wipes with some sandpaper couldn't help out.
I can only guess the cup gave me so much trouble because it is shallow, and therefore prone to being able to get quite a lot of angle before becoming stuck. It also became clear that everything is very tight on this bike, with close tolerances - my BMW gave me a much easier time when changing these bearings.
I had purchased some replacement bearings from All Balls, specifically kit 22-1040 which lists the Z125 Pro as being compatible. The Z125 Pro and the Z250SL are almost the same bike and use the same part numbers for steering head bearings so I thought this would be fine.
These turned out to be nowhere near the sizes I needed, much too small. I would hazard a guess that these bearings also DO NOT fit a Z125 Pro. I emailed All Balls to ask/tell them about my experience but heard nothing back.
This left me with a bike precariously perched on a bolt on a trolley jack and no way of putting the front back on. A quick trip to the local bearing factor with the lower yoke and bearings to hand gave me the sizes I need but they didn't have a taper roller for the bottom, only another thrust bearing (though this was from FAG and looked a lovely thing with the balls held in a steel cage..). A quick search on the Internet gave me the bearings I wanted, an "NTN 4TCR0643L/0643 Narrow Section Steering Head Set Taper Roller Bearing 30x52x16mm" for the bottom and a "48KS/30K Narrow Section Steering Head Set Taper Roller Bearing 30x48x13mm" for the top which turned out to be manufactured by ABC whoever they are. These were both purchased from Simply Bearings in the UK. You can of course buy a cheaper non-sealed bearing for the bottom but if it doesn't come with an extra separate seal to go under the roller part then you'll be changing them again quite soon.
As you can see from the invoice these bearings weren't cheap, but I didn't have much choice in the matter. The fact that I'd already spent £31 on the All Balls kit didn't help either!
With the new bearings procured simply bang the races into the headstock..
Seriously bang the roller on to the stem of the bottom yoke (it's really so very tight, unbelievable) and it's job done! And yes the bottom the headstock is not round any more.. Is it from the old race getting stuck or is it crash damage from serious force going through the lock stop? Who knows, the new race went in nice and snug so no worries. Right, anyone want to buy an opened but unused bearing kit for a KLX110..?