Inazuma 1200 Oil-Cooled Katana | Dramatically Improve “Push-Pull” and “Handling” with Wheel Bearing & Fork Oil Change

This week was hectic with arranging various materials and parts (´ー`)
I’m thinking this week is the last chance, so hopefully I can recover from any accidental mistakes.

I’ve got bolts, nuts, engine oil, fluids, and fork oil all lined up.
Moving to Chiba’s Soto-bo region was truly the right decision.
Most importantly, “test rides are so much fun!” is genuinely wonderful! I’m just being careful not to crash.

Maintenance Log for This Article

Vehicle: SUZUKI GSX1200 (Inazuma 1200 Oil-Cooled Katana Spec)

Work Performed:

  1. Wheel Bearing Replacement: Replaced front and rear wheel bearings with new ones.
  2. Fork Oil Change: Replaced degraded oil to restore suspension movement.

Purpose: Refresh aged rotating and sliding parts to restore the original smooth ride and light handling.

Result: The bike became surprisingly easier to push and pull, and road tracking improved significantly.

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I’ll go ahead and change the fork oil.

I’m constantly adjusting what “Deco-mainte” (inspection and service) should include.

Among standard maintenance checks, I’ve only seen a few cases of “quite bad, needs attention” from new customers.The tricky part is actually the follow-up care recommendations after completing a full service cycle.
Should I wait until things get really bad, or replace parts that aren’t that bad yet? That’s what I wrestle with daily.
For customers who’ve already had a full service cycle, the best approach is to
“leave the necessary work to me”and just do the work.That’s how I’ve been handling things lately.

Fork oil changes are quite labor-intensive work.
With simple upright fork designs, there’s not much difference in labor between a full fork overhaul and just changing the fork oil.
As a result, fork oil changes don’t get done as often, which isn’t ideal for the fork.
Keeping the oil clean and in good condition for longer means you’ll definitely enjoy riding more.

Once you use a vacuum pump for bleeding, you can’t go back.
You won’t have to worry about even the slightest air pockets, so why not pick one up this year-end?

M20×P1.5 to fit the GSF1200 straight axle shaft

To be precise, the fork span is only 5mm shorter on the GSF1200 at 200mm, but it fits just right when installed.
The Inazuma 1200 has a narrower outer diameter at the threaded section, so the bottom case needs to be machined.

The axle shaft is definitely designed for BITO R&D.
Please note it can’t be used directly on the Inazuma 1200.

When you buy a used bike, the wheel bearings are usually shot

OEM bearings usually only have an oil seal on one side.
Unless something’s really wrong, they won’t leak completely.
Used bikes have typically been around for quite a while.
These days, wheel bearings rarely seize up completely—they’re actually quite long-lasting.
But they’re definitely worn, so there’s more play. Replacing them right away after buying a used bike might actually be the secret to enjoying it more.



Bikes can have various modifications over time.
Taking measurements and comparing them to specs increases your confidence.

Wheel bearings have manufacturer-specified installation directions, so be careful.
Position adjustment is also needed, and there’s a bit of a knack to it, so pay attention.

The J-TRIP frame stand is a must-buy item

The day I dispose of my homemade frame stand is getting closer and closer.
Next May will mark one year since I moved.
If I haven’t used the homemade frame stand by then, it’s a candidate for disposal.

This frame stand’s finish and convenience are so good it definitely ranks in my BEST BUY TOP 5.

Definitely ranks in BEST BUY TOP 5 ♪

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The fact that the handlebar can be removed after lifting is the key!
By being able to remove it,“it prevents the stand from coming off if you bump something”

A stand with amazing design, adjustability, usability, and safety
It’s a product for people with some experience, but I think having one—or even two—is worth it.
I’ll add another one when the timing is right (*´ω`*)

The extension bar comes off with one push.

J・TRIP OFFICIAL online shop
¥38,500 (2026/09/21 07:35時点 | 楽天市場調べ)

Let me do a quick overall inspection

I cleaned the calipers and changed the brake fluid.
I trust Golden Cruiser DOT4 brake fluid.

The plug color is a bit uneven, but the condition isn’t bad.
Since Watanabe is installed, I’ll widen the gap and replace with new NT4245 plugs.

I might want to clean the carburetor at some point too.

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Joshin web 家電とPCの大型専門店
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The air filter was replaced last time, so I reused it.
I also cleaned the air cleaner box and pulled the drain hose.

Charging the battery and removing the fuses from the fuse box is like a ritual I do every two years.
I’m praying everything stays at 100% and no problems occur.

Using OEM 36618-43410 to cover the digital temperature sensor

This cover is for the oil pressure switch, so the inner diameter is a bit large.
Wrap a cable tie around the oil temperature sensor to create a groove, and it actually works surprisingly well.

I don’t like things that are hard to use, so I cut the tip and use it.


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I changed the engine oil to Shell Advance 4T Ultra.

I want to think about an Insta360 X5 mount

I’m aiming for a mount that
minimizes vibration, allows easy position adjustment, convenient attachment/detachment, and is easy to obtain.

I think almost 100% of people who buy phone holders and mounts end up disappointed.
The problem is usually that they can’t mount it where they want.
Thinking about what you really want before choosing a product might get you closer to your goal.

I struggled without having the camera body.
I’m also considering that it shouldn’t fall off and should be easy to remove when parked.

Mirror mount style 1-inch ball.
Back in the day, only RAM existed
FANAUE 1-inch Ball Mirror Mount Base for 10mm Bolt Holes MB-01

I like the surprisingly high quality feel.
My only complaint is that if you don’t put the nut with the chamfered side down, the clearance is too tight.
But it works fine anyway.

REC-MOUNTS BB Standard Ball Joint Arm 62mm Total Length (BB-62)

A ball joint arm that moves in four directions—eye-opening.
And this 62mm length is the key. Compared to standard arms, the range of motion is completely different.

レックマウント(Rec-Mounts)
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Finally,
RAM MOUNTS Camera Mount (Small Base) Black RAP-B-366U

The 1/4 threads are securely held by the seating surface, so it’s reliable.

ラムマウント
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If you want quicker attachment/detachment.

Insta360 X5/X4/X3/Ace Pro 2/Ace Pro/Ace/ONE RS/ONE R Quick Release Base Bracket Insta360 GO 2/GO 3 ONE X/ONE X Compatible Aluminum Quick Release Mount Adapter Base

The price is considerable,and if you mount the X5 vertically and use it on a bike, there’s an increased risk of it falling off.
I tend to forget to lock it…
Basically, it won’t release without pressing the button, but there’s still some risk.
Try it as is, and if you find attachment/detachment tedious, then go ahead and buy it.



I filled up with gas at a JA station you don’t see in Tokyo.
Lately I’ve been thinking this full-tank service is really important.

There’s something appealing about being able to pick it up and head straight to the highway.
Next is just waiting for the Qi-charging Quad Lock to arrive.

Undercarriage Refresh for Inazuma 1200 “Oil-Cooled Katana”. Work Performed:

Wheel Bearing Replacement: Replaced old bearings to reduce rolling resistance.

Fork Oil Change: Refreshed the front suspension fluid. Result: The bike is now significantly easier to push and pull, and the handling has become much sharper and smoother. Essential maintenance for any vintage bike project.

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