The world is in chaos, Covid-19 is killing sick people left right and centre and almost everyone has been told to self-isolate.

This of course means you can spend some quality time with the one you love (to ride)… your motorcycle(s). In my case I’ve noticed my 1994 zx-9r is leaking oil somewhere near the gear change lever and from both fork seals, while my 1998 ZX-9R C1 bike, the front brakes are binding slightly.

Since its been a while since I did some work on these bikes (see then its not surprising that something needs attending to. The zx-9r’s get used everyday so the wear and tear is a lot more than my older classics.

With oil leaking out of both seals, I dropped into Rad Hardchroming to get a second opinion. At first glance the guy who owns the business thinks the legs look OK and it most likely the seals (I fitted Pyramid Parts seals), he didn’t like the seals I had chosen so this time I will fit a better brand.

So this month I have two major jobs:

  • Disassemble the front brakes from the 98 C1 bike and remove the pistons, clean everything and re-assemble with new seals while I am at it.
  • Pull the fork legs apart on the 94 B1 bike, check the lower leg for scoring and if needed get them re-chromed.

1998 zx-9r Brake Service

Easter Friday – stuck at home – So with no kids at home and my partner looking after her sick sister it seamed like a good time to attack the brakes!

Thinking it would be a quick job I pulled the left caliper off, dropped out the pads and started to pump the front brakes. To my surprise, only two pistons moved out so a full strip would be required.

If you look carefully you can see a build up of crap at the top of each piston. This tells me that the pistons will need a bit of work.

This is why they the brakes are causing an issue, only two pistons in this caliper are free.

I used this opportunity to see how bad the other pistons were before I started a full disassembly. Using a block of wood, I cut a section out to make space for a piston to pop out, this gives me a chance to see how bad each one is and the picture below shows the result.

Using a block of wood allows pushing out each piston to see what they look like.

I used the block to pop each piston out and pushed it back in by hand. I’ve only had the bike for about 5 years and not serviced the brakes so stuck pistons are to be expected.

I gave this a quick clean before poping out the middle piston by hand, the gunk build up is pretty bad but will clean up fine.

After a short time I had the calipers apart and removed each piston by hand, the right hand calipers were worse than the left, not sure why?

Hint: If you intend to separate the calipers, loosen the 4 retaining bolts before you unbolt the caliper.

After separating the caliper halves and removing the pistons, the extent of the gunk build up was obvious. Strangely the brake fluid in the master cylinder was clean.

It took me most of the day to strip and clean the calipers, there was a lot of build up and I really wanted everything to be as clean as possible. The picture below gives an idea of how much crap had built up compared to one I cleaned.

Clean verses dirty, after a few more minutes I managed to get all the yellow fluid residue out.

It took about 4 hours to clean out the caliper bodies and then polish the pistons to a nice smooth finish.

Finishing Up….

I fitted new seals with a small blob of brake grease, pushed the pistons back in and rotated them as they went in. I also went to the effort of cleaning the threads of the bolts on a wire wheel and reassembled the two halves.

A small amount of lock tight on each bolt and a polish of the head of the bolts finishes off the task. At this time I fitted the pads and slid the calipers back onto the forks.

Once fitted on the forks, connect the brake lines, open one bleed nipple and begin bleeding a caliper, then the other and come back to the first. Bleeding the brakes is a simple task and there were no issues getting fluid in and air out. A speed bleeder might be on the cards for next service!

The only annoying issue of the whole process was fitting the dust seal on the smaller pistons.

If you need to order bits, below is the 1998 C1 parts list:

1994 zx9r Forks

Note to self – todo – fork disassembly!

I have parked the bike and am preparing to strip out the forks. I’ve done it three times in six years but never taken photos so this has presented a great opportunity to record how its done on a set of “upside down” forks.

z650, z1a and GPz1100 Update

April status for the z1a, z650 and GPz1100.

The z650 has a leak in the sump as a pool of oil built under it a couple of days after I assembled it.

The z1a engine is 90% assembled, I will look at what is needed and get busy, and I will document what has been done so I know where I am up to.

GPz1100B2 – needs a new 530 chain. With the lock down and un-essential travel banned, I have not ventured out to a bike shop, however I better do that this weekend and get a chain, after that I need to have another go at the tank.

I have located a spare B2 tank and even managed to get an extra B1 tank as a spare. I’ve asked the seller of the B2 tank to send me some pictures and a price including shipping. Hopefully its both repairable and reasonable to purchase.

In the mean time I need to get some molasses to clean out the existing B2 tank and the newly acquired B1 tank.

More to come….. next month!


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