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Inazuma 1200 Oil-cooled Katana Rear Brake Master Cylinder OH and Newtech Oil Change

Everyday Events (Work Log)



Thank you as always for the Inazuma 1200 oil-cooled Katana. The rear brake was pulsing, so it was an emergency pit stop.
The dust seal had protruded out. The fluid was leaking through the gap created by the compression.
The dust seal grooves on non-anodized calipers typically become jagged like this.
“Jagged grooves → deform the dust seal and corrode it → piston sticks and rear rotation becomes sluggish.” That’s how it works.

If the caliper piston is stiff, just washing the caliper and massaging it won’t be very effective unless the caliper is in good condition to begin with.

If you’re going to spend time massaging it, I think doing an OH would be better in the long run.
We polish it smooth. Interestingly, once it’s in this state, it doesn’t corrode as easily.
On the other hand, if you buff it to a shiny finish, it seems to corrode more easily. *Though that’s just my impression…


Work like this is really tough without the right tools. It takes time and the finish ends up being so-so.
When the person doing the work thinks “it’s not going to get that clean anyway,” the customer doesn’t feel much excitement either.
It’s more like “well, it works, so that’s good enough.”

But still, if it could look as nice as it did when new… or at least reasonably clean… that would be nice.
I think that’s what hobbies are all about.
Already at 75,000 kilometers and the paint was peeling badly. This time I stripped it off on my own.
It’s finished in matte silver bare metal. I don’t think it will corrode much, and since it’s unpainted, if it gets dirty we can just polish it again.
We also did an OH on the rear master as a set. This really does get dirty… The corrosion on the carburettor and rear master makes the bike look much older.
Probably… it’s cleaner than new. Both the technician and the owner are happy.
The umbrella spring is closing up. Initially it has tension and fits snugly against the inner wall. It opens responsively so there should be minimal play in the brake feel.

When it sags, it becomes spongy and mushy.
It’s a habit, but when assembling calipers and masters, I bake them once to dry them crisp.
Blowing with compressed air works too, but… what if… something’s still left behind? Is the mist from the air being removed? If you’re worried about that, this method puts your mind at ease.
When you open a package, it’s definitely safer to inspect it. The manufacturer’s packing is done by people too.
One in a thousand, one in ten thousand—it really can happen. If you assemble it as-is, whose responsibility is it? If you didn’t notice and assembled it, it falls on the technician… that’s for sure.
We apply CCI metal rubber with a brush. Surprisingly, it’s economical and doesn’t splatter, so it’s all good.
The split bolts are good ones from the later Bandit 1200 and similar models.
This small hole is critical to check. If it clogs, it can really lock up and be dangerous.
And that’s how it turned out. The rod was painted with Guncoat.
When something gets clean, you repair it and feel satisfied. I think the throwaway culture of “it’s dirty so let’s just replace it” will decrease.
We finished up with an oil change using Newtech NC50 10W-50.
Everyday Events (Work Log)
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