[Service Log] GSX750S Katana Custom Vehicle—Eliminating Handling Anomalies! Complete Realignment and Friction Reset of All Components for a Fresh Start
The long rainy season has finally cleared, and the best riding weather has arrived! Everyone, is your bike ready to go?
Before you know it, we’re already in double-digit month (October). All work reservation slots for 2026 are now full (※ Those who have already contacted us and made reservations can rest assured—we have you locked in).
I try to avoid saying things like “I’m busy” or “I can’t keep up.” It creates unnecessary stress and actually concentrates more requests. Our long-time customers understand both their own hopes and our work pace deeply, and entrust their bikes to us—I’m truly grateful.
Starting next year, I’m thinking of opening up just a few slots for “new customers.” When we formally announce it, I’ll make a proper announcement, so thank you in advance(´ω｀)
It’s been a while since I used a Sunstar drive chain
It’s so masculine. “I love iron,” he saysso I also installed it without plating for the first time in my life.
The exhaust pipe fits the oil-cooled version
One step forward, three steps back… Custom vehicles like this really do have all sorts of issues.
The cylinder pitch is the same, but the “flange pitch and exhaust gasket diameter” are different.
I noticed it when I removed the exhaust and saw the gasket deformation.
I’ll look for a gasket with the right outer and inner diameter. The problem is it’s thin… So I won’t write about it.
The outer diameter is too tight to fit… I can’t use a lathe, so I’ll hand-fit it to the actual part. What am I even doing… Next time, please use this Kitaco XK-15.
For now the exhaust is on and the exhaust leak is stopped
Front maintenance and inspection
I wipe the tires with water and check for any foreign objects.
The brake disc thickness is fine too.
The bearing condition is fine. The front clip was okay… I put a rotation sticker on it so you can tell at a glance.
I wet-blasted the wheel spacers to hide the surface. The width varies slightly left to right, so be careful. I’ve marked them.
The axle shaft runout is fine. Just cleaning and oiling the fork makes a huge difference in how long it lasts.
Looking at each part like this really boosts your confidence.
Maximizing current performance. Brake maintenance
I sand the brake pad surface and peel off a layer. This Brembo is a pin-less type. I chamfer it so it moves smoothly.
Brake pads don’t wear evenly top to bottom, left to right. The more you use them, the bigger the difference becomes, so“you shouldn’t use them down to the wire.” The brake disc will wear unevenly.
Anodized calipers with aluminum pistons are really nice. Dirt doesn’t stick to them, and performance doesn’t drop off.
The bleeder nipple being on the inside is a bit of a pain.
I’ll degrease the brake disc thoroughly and then bed in the fresh brake pads hard.
What parts are currently being used?
You need to know how many holes, what size, and what offset. But this is a modified aftermarket part… There’s been so much work done all over the place that the specs are just weird.
While I was at it, I remade the center spacer(*´ω｀*) I made sure it centers on the bearing.
Cold compression and spark plug replacement
We’re getting about 1 MPa across the board, but #3 is a bit low. Since it’s cold, it’ll be higher once the engine warms up.
The reason we check cold is “an engine that’s solid cold starts sharp.” Once it warms up, the numbers should be decent.
Spark plug DR8EA ⇒ JR8B is good JR8B is a spark plug made for oil-cooled engines—basically a more durable version of the DR8EA. There’s no real reason to use DR8EA, so for installation and specified vehicles, JR8B is the only choice. *If you’re worried, leave it as is The tip is cut and it’s less prone to breaking from vibration.
Battery charging and output voltage check are important
Please charge the battery to full once in a while. While riding, it doesn’t charge as much as you think.
A weak battery means weak ignition. To get a snappy spark, start with a full charge.
Keep the headlight on all the time and use the power you generate.
The current regulator shows about 15V headlight OFF, 14.65V ON. Seeing 15V again after a while is thrilling. By running with the headlight always on, you consume the power you generate and don’t burden the regulator.
We also did control lubrication and fluid replacement.
Autumn sunshine is the best(*´ω｀*)Enjoying the countryside
I took it out on our usual test course. It’s not bad, but it feels a bit sluggish… Can you tell what I mean?
When I spray parts cleaner, it’s sucking it in a bit.
The intake manifold wasn’t replaced during the engine overhaul. Or maybe it was never even removed…
At my level of junk lordship… I have used ones. Our customers often replace them even though they’re still good, so I keep them as samples. Still usable, so free! *Fast turnaround too!
The FCR spigot won’t come out. No wonder it’s sucking…
FCR uses liquid sealant to seal the spigot. Everyone wants it to be an O-ring like TMR.
Gasoline-resistant liquid sealants are very rare. Semi-dry is standard, but this one dries almost completely, so it’s safe to use.
[Service Log] GSX750S Katana Custom Vehicle—Eliminating Handling Anomalies! Complete Realignment and Friction Reset of All Components for a Fresh Start
ポチップ
