Air-cooled 4-cylinder with no overheating? XJR1200 K Factory clutch release fluid and engine oil change

The first large-displacement motorcycle I ever owned was an XJR1200 (salvage title).
I was really surprised by its sheer size and torque, you know?

Since it had the same color scheme, it brought back some nostalgia.
Even looking at it now, I still think it’s a pretty nice design, but it’s strange how it never really caught on in popularity. Don’t you think?
It’s actually a really great bike.

Anyway, let’s get the work underway.

デイトナ(Daytona)
¥3,551 (2026/09/21 02:35時点 | Amazon調べ)

(Free motorcycle appraisal and sale with the rumored KatieX! This is the new way to sell.)

K Factory XJR1300 clutch release

It goes from 38Φ to 40φ, just 2mm larger.
If you look at the image of the stock piston, you’ll see
that the contact surface is very small, so Yamaha clutch releases tend to weep fluid easily.
Swapping in this part is a good preventive measure, I think.

Subjectively, it feels a bit lighter, but that’s about it.
Don’t expect dramatic changes.

K-FACTORY
¥39,600 (2025/04/02 19:47時点 | Yahooショッピング調べ)

Even though it’s new, I’ll remove the piston and apply metal rubber before reassembling.
That should help with initial break-in.

Engine oil is Shell Advance Ultra!

The engine oil came out nice and black.
I replaced it along with the filter.

I use Golden Cruiser DOT4 brake fluid.
Golden Cruiser is handled by CCI, which is metal rubber—it feels like the action gets smoother, kind of.

I already assembled the clutch, so there’s no photo.

If I’d just done the work without worrying about all the details, it would’ve been done long ago.

I was looking for a black stock bolt with an M8 thread and 20mm under-head length for the brake disc.
At first I made a mistake and ordered the same 25mm under-head length.

After a lot of searching, I found what I thought was the 20mm version, but the seat was slightly too small to use.
In the end, I had to cut this 90109-084F7 down by 5mm.

ヒロチー商事 ハーレー 楽天市場店
¥209 (2026/09/21 06:35時点 | 楽天市場調べ)

Stock bolts really do look right, don’t they?

I cleaned the drive chain and re-lubricated it.
The adjustment looks fine.

The seat lock action was a bit stiff, so I lubricated it slightly.
That’s it—all done!

K-FACTORY
¥39,600 (2025/04/02 19:47時点 | Yahooショッピング調べ)
デイトナ(Daytona)
¥3,551 (2026/09/21 02:35時点 | Amazon調べ)
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