Kawasaki ZX9R E2

[dern]

Picked this up before christmas and it's been waiting for a service before I ride it...

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It needs a proper service and I'm about halfway through it. The stuff on the list is...
- Throttle and clutch cables - done
- Air filter - done
- Oil and filter - done
- Spark plugs - done
- Check valve clearances - doing
- Refurbish brakes
- Change coolant
...and I'm sure there's some stuff on the white board in the garage that I've forgotten to put in this list. It all looks ok so far, the oil looked excellent but the air filter was completely borked.

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[dern]

Valve clearances are out of spec so next job is cams out...

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It's not too bad but it's well over the interval at 16k miles and 23 years!

By the way, if you're servicing your own bike and you've decided not to check and correct valve clearances because you've read some anecdotal evidence that some bloke once did 80k and the valve clearances were spot on then you're not servicing your bike. Give it to someone who knows what they're doing.

[dern]

I'm going to pull the front calipers off at lunchtime to see if I need pistons as well as seals for the caliper rebuild. I've read that while upgrading the calipers can see an improvement, upgrading the master cylinder to a radial setup can bring better feel. I've read that buying a master cylinder from something like a 2004 R1 or R6 of the same period would work but I don't want to simply buy something and hope. What do I need to do to figure out if a particular master cylinder will work with the calipers? I'm assuming that as well as it physically fitting on the bar I need to make sure that the master displaces at least as much fluid on operation as the original... is that kind of information available or is it a case of trying stuff until it works or buying an expensive aftermarket master made for the purpose? Thanks.

[KungFooBob]

You have to work out the ratio of MC diameter to total piston area, there's a magic ratio that feels 'right' but I can't recall it.

I used to have a bookmark with all the calcs, but I can't find it now.

Edit:

Ah-ah!

http://www.vintagebrake.com/mastercylinder.htm

You probably need a version that covers twin discs tho'

[dern]

Ah, cool... thanks.

[mangocrazy]

What's the piston diameter of the current master cylinder? That will give you a starting point. I seem to remember that the Tokico 6-pot calipers weren't highly regarded at the time, feeling wooden by all accounts. That could of course be down to the m/cyl. I played around with different master cylinders on my LC and the standard 5/8" m/cyl felt wooden whether I used OE Yamaha or Brembo Goldline calipers. A 1/2" m/cyl took away the wooden-ness but at the expense of spongey feel. When I switched to a Brembo 16mm m/cyl with the Goldlines feel and power were spot on.

[Mr. Dazzle]

Just gotta think back to your O-Level/GCSE physics innit.

The brakes are just a pair of hydraulic rams (the fact the calliper usually has more than one piston isn't super relevant, it's a second order effect, it's the total area of the calliper pistons you need to think of). If the MC is half the surface area of the calliper pistons, the force you put in is doubled but the MC moves twice as far as the calliper pistons. The real ratio won't be 2:1, that's just an example.

I simple terms, if you make the MC smaller it'll move further when you squeeze (probably feels spongier) but it also provides more braking 'power' for the same force at the lever. And vice versa, a bigger MC 'amplifies' your grip less so it feels more wooden.

Pretty much pure personal preference as to which is better.

Mango you're triggering me with your mixed units

[dern]

Just took the calipers off and the seals are blown out in a few places, there's crusty shite on the pistons so they're scrap but the bores in the calipers look good. Just need a refurb kit with pistons now.

[mangocrazy]

Mango you're triggering me with your mixed units

Merely quoting the stamped sizes on the m/cyls... Yamaha, for all their being Japanese, used imperial sized m/cyls in the early 80s. And (as we've discussed before) good old BSP is alive and well in at least half the globe.

Anyway, back to dern's brakes... Powerhouse in Chesterfield offer a wide range of caliper refurb kits, especially for Japanese bikes.

[KungFooBob]

As the crow flies, I'm sat approximately 287m away from Powerhouse right now

[MingtheMerciless]

Mango you're triggering me with your mixed units

Stay away from the railway then.......distances are in miles and chains and tolerances on equipment is usually in mm.

[Ssray]

I used this when changing the brakes on my zzr11.
The same size radial master cylinder should feel better than the current one as there is a more direct path for the force from your fingers.

http://202.51.14.75/galespeed_en/01_master_ratio_d.html

[dern]

I used this when changing the brakes on my zzr11.
The same size radial master cylinder should feel better than the current one as there is a more direct path for the force from your fingers.

http://202.51.14.75/galespeed_en/01_master_ratio_d.html

Great, thanks very much.

[dern]

Front and rear callipers rebuilt, installed and bled.

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[dern]

Valve clearances all adjusted…

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Probably could have saved a lot of time by subtracting the shim difference instead of adding it. Would have only had to do the job once then. Don’t think I’ve done that before.

Also flushed and refilled the coolant.

Just need to put new chain and sprockets on and give it a clean.

[ZRX61]

Step brother had one of those.

[Dixiethedog]

Great project. And it is cool to see that you are doing things properly.

A good mate of mine has a ZX9R C (I think that it is a C model), anyway, it has factory standard immaculate blue candy paint, ZX10R front forks and brakes, a Z750 wheel (that looks like a ZX10R wheel, but cost a lot less),a ZX10R complete rear end (swingarm, wheel, brake...), a gel rider seat along with a lovely Renthal bar conversion. Done with a nice CNC top yoke. He retained the front fairing, but had to modify the metal brackets (I think?) that go to the screen. If you did not it had been done you could walk past it and pay no attention to it as it looks totally factory built. It also has Aliexpress rear sets that he rebuild with all new bearings rather than the rubbish Chinese bushes. And best of all, it is lovely to ride. It is as comfy as anything that I have ever ridden. The screen may have been cut a small amount? It might be totally different to what you want to achieve, but it shows that you don't need the latest 2025 super expensive type of bike to have something that is a lot of fun.

Good luck with yours!

[A_morti]

Looking like a proper job @dern

The master cylinder question is more complicated than it first seems. On the one hand it's just a bunch of hydraulic cylinders, but on the other there's also a difference in the physical leverage applied by different design levers on different brands and also designs within the same brand. EG a 1/2" master cylinder off a Honda Grom behaves more like an 11mm master cylinder off an 89 honda cb-1, than a 1/2" master cylinder off a 90s Hornet 600, but all are from Nissin. For the same reason, radial master cylinder bore sizes are all-but unrelated to axial master cylinder sizes for this purpose.

Long and short of it is, if someone else already did a radial conversion and rates it, you could do worse than follow down their path.

[dern]

All finished and runs like a dream. Brakes feel very strong indeed.

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I’ll ride it through the summer and then take it to bits and restore some of the bits that need more than just cleaning and service the suspension.

[dern]

Considering I bought this on a whim, this is a great road bike. Plenty of power and feels easy and comfortable to ride on the road. Really happy with this one. I’m sure I’ll get bored of it at some point but for now it’s excellent.