How to "do" the valve clearances on a Kawasaki Z250SL

So you've got to 19473 miles and getting twitchy because you've not checked the valve clearances since you last looked at 8470 and Kawasaki recommend a check every 7600 miles (it's surely not just me??). Upon checking you find the clearances are all right at the tight end of the spec except for right exhaust which is just a smidgen too tight. Here's what you do..

Firstly you need to get access to check the clearances (if you have not done so already). You can find my world-class guide right here. Now on to the interesting stuff.

This guide starts assuming you've already got the rocker cover off and have already tried to get your tool to fit but the hole is even tighter than you wanted. The first step is to remove the inspection cap from the alternator cover, a neat trick I learnt on BAT is that you can use a coin and a pair of pliers to turn out the cap without mashing it up like you would with a big screwdriver that doesn't fit the slot. Happy days!

If you're in the UK then a late, steel 2p is just the ticket. If you use a copper one it will just bend and twist. If you're not from the UK then you're on your own.

Next up is to put the bike in 6th gear and turn the rear wheel in the direction it would turn when travelling forward, this is to turn the engine over so that you can line up the "T" mark on the flywheel with the notch in the inspection hole. You'll probably miss it the first time but don't worry. If you do miss it then carry on going round, do not try and go backwards as you'll be hammering against the starter clutch.

With the crank at "T" hopefully the cam lobes are all miles away from pushing on any buckets - this is TDC on compression and actually you should've found this when checking the clearances so why are you doing it again here? If they are touching buckets then go round back to "T" again.

With that sorted it's time to remove the cam chain tensioner. This is on the right side of the motor, funnily enough where the cam chain is.

Remove the large bolt in the centre first to remove the spring tension and the tensioner's need to extend (which could possibly strip the threads for the mounting bolts when they're halfway out). This will pop out with the spring but not very strongly, don't worry. With the big bolt and the spring removed feel free to remove the two smaller mounting bolts, I used two different spanners to get at the inner one.. What a pain it is.

With the tension off the chain we can now remove the one-piece cam cap/holder/thing. In order to get to the bolts at the front you may find it best to slide this doodad off its peg:

And then it's just a bit of lefty loosey.

The holder has numbers cast into it for each bolt, start at the highest number (8) and work downwards. Crack them a bit, then go round again, and then maybe again to actually fully release them. If you fully remove each bolt straight away then you risk warping the cover which would be a Bad Thing.

Notice how the exhaust cam has a notch in it's holdy-in-placey-disc thing. That is all that differs it from the inlet cam so don't go forgetting!

As a side note I have no idea what this is for but it's great because it stops the cam chain from falling down the tunnel. Thanks Kawasaki!

It's even sealed on the outside, all this work and expensive for what??

After all that simply pluck the came out, lift up the left side first and as the shaft pivots it'll take the tension off the chain. Do whatever works for you. With the cams out we're at the buckets, easy innit?

Time to remove the buckets. These have to stay pristine so don't go grabbing them with pliers. I find a magnet on a stick works incredibly well, they just slide up and out.

And the shim:

Alright that's probably not true and the shim is stuck inside the bucket but this is where it's supposed to be.

Simply measure the shim with a micrometer (you've got a micrometer right? You better had because the size markings were all worn off the shims I took out..) and then do what you like but make sure not to mix up the buckets and their holes because they can be a matched pair. I just measure each shim one at a time and reassemble them before moving on to the next one. I also take notes of what I find with the micrometer but again that's up to you, perhaps you're some kind of memory genius. Compare your shim sizes to the clearances you found and do the appropriate calculation to find out you need to buy some shims. For reference this is what I found at 19473 miles:

Clearance spec from Kawasaki:
Inlet: 0.10-0.19mm
Exhaust: 0.15-0.24mm

My clearance findings:
Left inlet: 0.10-0.15mm (kinda tight on the feeler, mebbe 0.12ish?)
Right inlet: 0.10-0.15mm (even tighter than the left one)
Left exhaust: 0.15-0.20mm (tight on a 0.15mm feeler)
Right exhaust: 0.10-0.15mm (just under 0.15mm, 0.10mm feeler slips in and out)

Shims found in my motor:
Left inlet: 296
Right inlet: 301
Left exhaust: 292
Right exhaust: 291

This meant that I could use the 291 in the left inlet and the 292 in the right inlet and they'd be right up at the looser end of the scale, so that's a few quid saved. Unfortunately I did have to buy a 285 and a 280 for the left exhaust and right exhaust respectively. I actually bought some aftermarket shims from "dirtbikestore" which were much cheaper than Kawasaki items and proved to be machined bang on spec as confirmed by my micrometer - recommended!

Installation is pretty straight forward if you've got this far, pull out the buckets and shims again and pop in your new shims. Give everything (including the shims!) a coat of oil before putting it back together, just a dribble over it in place is fine.

Ensuring the buckets are all fully rammed home and the crank is still at "T", start fitting the cams back in. I found it easiest to fit the exhaust cam first, it gives you a bit more slack to play with. Fit the specially ribbed exhaust cam back with the "EX" marks horizontal along the top of the head, ensuring there isn't enough slack in the chain to allow it to move out of time - the chain at the "front" needs to be quite taught to make sure the timing is right.

Now the real game begins, fitting the inlet cam into the chain so that the "IN" marks stay horizontal with the top of the head but also making sure the exhaust cam doesn't go out of time. This took me several goes but they both need to have their marks lined up with the top of the head. There's also not a lot of slack in the chain to add to the enjoyment. Eventually..

Next up is to fit the cam cap holder thinger. Did you notice the shiny steel cap things in it?

These are used at the factory to prime the holder with oil so that the cam doesn't run dry for the first few revolutions. The manual says to make sure that these cap things are still securely in place after installation because the air pressure from mounting it could cause them to pop out. I forgot but you should remember!! Anyway..

Use the numbers cast into the cam holder to know which order to tighten the bolts - handy innit! We're aiming for 12Nm on these bolts but as always do it in stages, first snug them down then aim for ~6, then maybe 10 and finally 12. If you don't have a small torque wrench then all I can say is 12Nm isn't all that tight.

We're most of the way there now but don't be tempted to turn the motor round just yet, we still have to put the tensioner back in. This is a standard ratchet affair, first you need to press on the "pawl" (the pivoty black bit) to release it, and then push the big black ratchety plungery tooth bit back inside.

If you don't reset the tensioner like this then you risk breaking something when you bolt it back into place. Speaking of which, bolt it back into place with the small mounting bolts.

Only now it is safely/strongly install can you reinstall the spring, bolt and washer.

Just shovel it all down the middle of the tensioner, it's not complicated, and tighten the end bolt until it's not going to fall off or let oil leak past the washer.

And that is pretty much it. Turn the rear wheel some more to make sure the valves aren't hitting the piston (another Bad Thing) and that the marks on the cam sprockets are still level and correct. If they're not then you have to go back and do it right, if they're fine then tighten the inspection cap back in and put all the ancillaries back on. Then, after all that, cross some fingers and thumb the starter.. Hopefully it'll go well enough but sound a bit more rattly, as is always the sign of a good job!(?).

Installing YSS PD Valves (a.k.a. cartridge emulators) in BMW K75 Showa forks

I originally wanted some of the Showa forks for my K100 so that they could be modified to take these valves, but they weren't leaking too badly when I got them so I just fitted them and got on with riding it. A year later though there was oil dripping right down a leg and very nearly on to the brake disc..

So, time to take action!

The Showas that BMW chose to fit to the K75 are as basic as you can get. First loosen and remove the bolt that is at the bottom where the axle for the front wheel goes and let the oil out (you can try and pump the fork if you want).

Next up is to try and get the spring and spacer and damper rod and gubbins out from the inside of the fork. Normally this would be easy but it appears BMW have insisted on using the same snap-ring design as on the earlier Sachs forks. This means the top has to be depressed against the spring and the clip fished out. This stumped me for a while but I finally figured out the best way was to clamp the stanchion in the lower yoke and use the upper yoke to give somewhere to lever the top down with a screwdriver, like so:

The ring may be slightly corroded in place, just to make it even more difficult to pick out. I eventually managed it with a dental pick/tool, they are really useful to have! So..

Don't forget to remove the clip above the oil seal before you try and pull out the stanchion, I definitely didn't do that twice.. Anyway, the bad news here is that (as far as I know!) the original springs are progressive, meaning they won't work all that well with the valves.

The good news is that the top of the damper rods are the normal cup shape, meaning the valve/emulator/whatever will fit fine without an adapter.

So, that's the fork in bits. Now the fun starts! Look at these puny little holes..

Where's my professional-grade weapon of choice??

Now, for PD Valves of size 265 or bigger (these take 310) YSS recommend having 6 holes which are 8mm in diameter and there must be at least 10mm between the holes so that the damper rod can still hold up the bike without buckling/failing. As an aside the top of the damper rod for these forks is 25mm and here is the size chart, weirdly only supplied by YSS in the instructions in the kit (so once you've bought them) and not mentioned anywhere on their website that I can find..

They fit like this, if you didn't already know:

Anyway, where were we? Ah yes..

File and deburr the edges so that you don't send swarf all round the forks and the oil isn't sheared to buggery by sharp edges (I used a very small round file which took a long time)..

So, with that done we need some proper springs. Not only do we need some that are slightly shorter to compensate for the new extra tall damper rod/valve combo but we also need some that are linear. The springs out of these 41mm Showas are only 32mm outer diameter which is actually really small if you start looking at fork springs, however there was a ray of sunshine - Harley Davidson fitted 41mm Showas to their bikes too, and it turns out they fitted shorter linear springs. A quick search on ebay revealed a place called Huggy's Speed Shop had some Harley springs in stock with a completely unknown past, they merely arrived in a container full of bits. £30 exchanged hands and they were mine, muhahaha! Harley spring and spacer on the left, BMW spring and spacer on the right..

Racetech recommend 30mm spring preload when fitting their emulators to a Harley with these Showas which seemed to be about as much as was originally intended judging by the way the fork top pinged off. So, I fitted the Harley springs with the shorter BMW spacer and this little bit of magic happened at full extension:

Given the depth of the fork cap that is pretty much spot on. The springs are still completely unknown so I have no idea what their rate is but a Harley is a heavy bike and the K100 is a heavy bike so what can go wrong? Onwards with the reassembly! Put it all together and fit the bolt back in the bottom so it won't all fall apart.

The top bush was a right bugger to get back in..

Some very unprofessional tools and techniques were employed..

But eventually it went in. Don't give up!

Put the washer in..

Put your new oil seal in, which was the cause of all this to begin with (I've fitted TTO seals for the first time here because a pair of NOKs were coming in at about £25 which is totally unacceptable, these were £6.34 and TTO are still Japanese so should be alright at least for a bit - at least they're double lipped).

Sadly not the first time I've used a punch to install new seals but sometimes you have to work with what you've got. I now have a seal driver, I'm sure I'll have the opportunity to use it soon.. Anyway, install the wriggly clip on top of the oil seal and that particular bit of nastiness is all finished.

Use the same trick to squeeze the cap back in the top and install the horrible clip ring thing.

And there you nearly have it. Tighten the bolt at the bottom (I connected both forks together with the fork brace so the legs didn't twist round), probably with the old copper washers because it seems they're a special size and then fill the forks with oil. A quick test trying to bounce a fork on the lawn revealed the new springs to seem very firm so I went with 10w oil and only 350ml of it compared to the standard 410ml. After bolting the whole thing up and tightening the yoke clamps I took the bike off the stand and normally it would sag quite a bit under its own weight. Now it just kinda sits there. It sags a bit when I get on but I had to adjust the rear shock to max preload and I still feel like I'm riding uphill so the Harley springs are actually very hard indeed. The movement of the forks is improved though, and get better the faster you go which seems to be a hallmark of these valves - I suppose they do come from the world of racing after all.

So, there you have it - if you try this, let me know how you got on and what oil/springs/preload/valve preload you went with!