{"id":2055,"date":"2026-08-27T20:08:26","date_gmt":"2026-08-27T11:08:26","guid":{"rendered":"https:\/\/www.decoboco.info\/en\/?p=2055"},"modified":"2026-09-24T12:54:44","modified_gmt":"2026-09-24T03:54:44","slug":"yamaha-sr400fi-statutory-inspection-sunstar-brake-disc-upgrade","status":"publish","type":"post","link":"https:\/\/www.decoboco.info\/en\/20260827\/everyday-events\/yamaha-sr400fi-statutory-inspection-sunstar-brake-disc-upgrade","title":{"rendered":"[Maintenance Log] SR400 (FI) Statutory Inspection! Elevating Braking Feel with Sunstar Brake Discs"},"content":{"rendered":"\n
\"\"<\/figure>\n\n\n\n

During inspections, I propose replacing various wear items.
There are surprisingly many parts that technically work but are in less-than-ideal condition.

I’m currently based in Chiba too, and I want to keep bikes in a condition where you can “ride carefree for two years without worry.” <\/span><\/strong>
You get both comfort and peace of mind, so riding becomes genuinely fun. <\/p>\n\n\n\n

Day in and day out, I live by the motto “no complaining, no criticizing.” <\/span><\/strong>(*\u00b4\u03c9\uff40*)<\/p>\n\n\n\n

Today’s Inspection & Brake Tuning Log<\/strong><\/span><\/div>
\n

Target Vehicle: <\/strong> Yamaha SR400 FI (Fuel-Injection Model)<\/strong><\/p>\n\n\n\n

Service Request: <\/strong> 24-month periodic inspection & statutory inspection + front brake disc replacement<\/p>\n\n\n\n

Parts Used: <\/strong> SUNSTAR Brake Disc Rotor<\/strong><\/p>\n\n\n\n

Inspection Highlights: <\/strong> Stem and swingarm play inspection, pivot point greasing, complete fluid\/plug\/oil changes.<\/p>\n\n\n\n

Disc Replacement Benefits: <\/strong> Eliminates OEM disc wear and step wear. Sunstar’s precision flatness and superior heat dissipation deliver a refined, linear brake feel that responds perfectly to fingertip input!<\/p>\n<\/div><\/div>\n\n\n\n

\n
\n
\"\"<\/figure>\n<\/div>\n\n\n\n
\n
\"\"<\/figure>\n<\/div>\n<\/div>\n\n\n\n

Chiba Relocation 1st Anniversary Inspection Certificate Holder\u2014Limited Stock Available! (*\u00b4\u03c9\uff40*)<\/a><\/span><\/strong><\/p>\n\n\n\n

<\/p>\n\n\n\n

\"\"<\/a><\/figure>
\n

My other BLOG, Decoboco.
“RURAL GARAGE<\/strong>“<\/span>

A hidden room beyond bikes.
I share everyday convenience items, relocation stories, delicious meals, life philosophy<\/strong>and more.<\/span>
\u2190click<\/span><\/strong><\/p>\n<\/div><\/div>\n\n\n\n

<\/div>\n\n\n\n
\n
\t\t
\n\t\t\t\t\t\t\t
\n\t\t\t\t\t\n\t\t\t\t\t\t\"\"\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t
\n\t\t\t\t
\n\t\t\t\t\t\n\t\t\t\t\t\tSR400 ProSelect Bike GL-PS4B-BS Nano Gel Battery (YT4B-BS, GT4B-5 compatible) (Gel type, pre-filled and charged) PSB103 sealed MF battery\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\n\t\t\t\t\t\t\t\t\t
ProSelect<\/div>\n\t\t\t\t\n\t\t\t\t\t\t\t\t\t
\n\t\t\t\t\t\t\u00a53,070\t\t\t\t\t\t\uff082026\/09\/21 13:36\u6642\u70b9 | Amazon\u8abf\u3079\uff09<\/span>\n\t\t\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\t\t\t\t\t
\n\t\t\t\t\t\t\n\t\t\t\t\t\t\t\"\"\n\t\t\t\t\t\t\t\u53e3\u30b3\u30df\u3092\u898b\u308b<\/span>\n\t\t\t\t\t\t<\/a>\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t
\n\t\t\t\t\t
\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\n\t\t\t\t\t\tAmazon\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t<\/div>\n\t\t\t\t\t\t\t
\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\n\t\t\t\t\t\tRakuten\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t
\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\n\t\t\t\t\t\tYahoo!\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t
\n\t\t\t\t\t\"\"\n\t\t\t\t\t\u30dd\u30c1\u30c3\u30d7<\/span>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t<\/div>\n\n\n\n
\t\t
\n\t\t\t\t\t\t\t
\n\t\t\t\t\t\n\t\t\t\t\t\t\"\"\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t
\n\t\t\t\t
\n\t\t\t\t\t\n\t\t\t\t\t\tSR400 Sunstar KC-401H Custom Type Disc Rotor Left and Right (Gold) KC-401H\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\n\t\t\t\t\t\t\t\t\t
\u30e2\u30c8\u30e1\u30ac\u30cd \u697d\u5929\u5e02\u5834\u5e97<\/div>\n\t\t\t\t\n\t\t\t\t\t\t\t\t\t
\n\t\t\t\t\t\t\u00a526,227\t\t\t\t\t\t\uff082026\/09\/21 13:36\u6642\u70b9 | \u697d\u5929\u5e02\u5834\u8abf\u3079\uff09<\/span>\n\t\t\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t
\n\t\t\t\t\t
\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\n\t\t\t\t\t\tAmazon\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t<\/div>\n\t\t\t\t\t\t\t
\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\n\t\t\t\t\t\tRakuten\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t
\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\n\t\t\t\t\t\tYahoo!\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t
\n\t\t\t\t\t\"\"\n\t\t\t\t\t\u30dd\u30c1\u30c3\u30d7<\/span>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t<\/div>\n<\/div>\n\n\n\n
\n
\n
\n
<\/div>\n<\/div>\n<\/div>\n\n\n\n
<\/div>\n<\/div>\n\n\n\n
\n
\n
\"\"<\/a><\/figure>\n<\/div>\n\n\n\n
\n
\"\"<\/a><\/figure>\n<\/div>\n\n\n\n
\n
\"\"<\/a><\/figure>\n<\/div>\n<\/div>\n\n\n\n\n\n\n\n
<\/div>\n\n\n\n

After four years of use, the battery performance is quietly impressive<\/h2>\n\n\n\n
\"\"<\/figure>\n\n\n\n

Lately I’ve been recommending this AGM-GEL battery for its reasonable price and high durability.
Rather than running a battery until it’s completely dead, replacing it after a certain period is best practice.

Startup performance improves dramatically, and interestingly, the overall feel seems to improve slightly too.
You might think it doesn’t matter since the alternator is charging, but it actually does. <\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

I check the maximum output voltage at various RPMs.
A little extra effort makes a huge difference in reliability. <\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Fuses are definitely worth checking during maintenance. <\/p>\n\n\n\n

\n
\n
\"\"<\/figure>\n<\/div>\n\n\n\n
\n
\"\"<\/figure>\n<\/div>\n<\/div>\n\n\n\n

Fuses are cheap\u2014if they look dirty, I just replace them.
This is basically a good-luck ritual (*\u00b4\u03c9\uff40*)<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Always give a new battery an initial charge.
Sometimes they arrive partially depleted. You want that full punch when you hit the starter button. <\/p>\n\n\n\n

Brake disc is Sunstar & Daytona Sintered<\/h2>\n\n\n\n
\"\"<\/figure>\n\n\n\n

Large center bore with a modern design.
Excellent compatibility\u2014I’m amazed at how many bikes it fits. <\/p>\n\n\n\n

\n
\n
\"\"<\/figure>\n<\/div>\n\n\n\n
\n
\"\"<\/figure>\n<\/div>\n<\/div>\n\n\n\n

The brake caliper was reasonably clean.
Piston operation is fine. <\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Single-piston caliper enthusiast here.
Fine deburring makes movement about 1% smoother. <\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

I clean the bolt threads to eliminate vagueness in tightness.
It’s subtle but makes a real difference in feel.
If thread-locker residue remains, torque can reach spec too quickly.
The question isn’t whether a bolt stays loose with thread-locker\u2014it’s whether it’s properly clamped and stays tight as it should be. <\/p>\n\n\n\n

<\/p>\n\n\n\n

<\/p>\n\n\n\n

<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Also, replace dust boots generously.
They cover the slide pins, and stiffness is bad news.
Always lubricate slide pins with silicone grease. <\/p>\n\n\n\n



I also use silicone spray to keep movement as smooth as possible during assembly. <\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n


As I’ve gotten older, I’ve come to appreciate single-piston calipers. <\/span><\/strong>And seeing cracks in aged dual-piston calipers (especially from Brand B),
I realize manufacturers really understand cost-benefit balance.
Braking performance has improved so dramatically with modern discs and pads…

that’s my impression anyway.
Heat-treatable stainless is limited, but… <\/p>\n\n\n\n

Oddly-shaped wheel hub<\/h2>\n\n\n\n
\"\"<\/figure>\n\n\n\n

Unique to Yamaha? I’ve only seen it on the SR400 in our shop. <\/p>\n\n\n\n

The hub has no bearing\u2014it’s a free-floating design.
Pretty innovative! <\/p>\n\n\n\n

\n
\n
\"\"<\/figure>\n<\/div>\n\n\n\n
\n
\"\"<\/figure>\n<\/div>\n<\/div>\n\n\n\n

The hub damper is still in good shape, so I reused it.
But I wanted to tighten clearance a bit, so I added POM shims.
This time I used six shims for 6mm of preload (*\u00b4\u03c9\uff40*)<\/p>\n\n\n\n

Turned out great and feels solid. <\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Replaced the drum shoes while we’re at it.
After vacuuming, I wet-blasted them to this shine \u2606
It’s not a visible area, but it should help a bit. <\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Assembled with Yamaha OEM parts\u2014perfect fit. <\/p>\n\n\n\n

Axle shaft and wheel bearing check<\/h2>\n\n\n\n
\n
\n
\"\"<\/figure>\n<\/div>\n\n\n\n
\n
\"\"<\/figure>\n<\/div>\n<\/div>\n\n\n\n
\"\"<\/figure>\n\n\n\n

Axle shafts rarely bend, but it’s good to check anyway.
I also inspect and adjust wheel bearings\u2014 knowing the bearing number <\/strong>makes ordering easier later.
Most people don’t order OEM wheel bearings, but…
it’s handy to know (*\u00b4\u03c9\uff40*)<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

I also lubricated the speedometer cable.
Honestly, I’ve never seen anyone break a cable. <\/p>\n\n\n\n

\n
\n
\"\"<\/figure>\n<\/div>\n\n\n\n
\n
\"\"<\/figure>\n<\/div>\n<\/div>\n\n\n\n

Replaced fluid, air filter, and spark plug too.
The SR400’s simplicity and serviceability are why it’s so beloved. <\/p>\n\n\n\n

Test ride before the rain\u2014chop chop! \u266a<\/h2>\n\n\n\n
\"\"<\/figure>\n\n\n\n

Thin tires like this are genuinely wonderful.
There’s real feedback and it’s incredibly fun.

Going wider for looks is totally valid, but
“wait, something feels off?” <\/strong>\u2014I bet many people have felt that.
Manufacturers really nail the balance.

The FI version starts so easily\u2014nothing like the old SR!
It fires up almost instantly, so even people who hated old SRs can come back to this.
Light, punchy, comfortable seating, and it feels like you could ride forever.
Braking and cornering feel refined now. <\/p>\n\n\n\n

\n
\t\t
\n\t\t\t\t\t\t\t
\n\t\t\t\t\t\n\t\t\t\t\t\t\"\"\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t
\n\t\t\t\t
\n\t\t\t\t\t\n\t\t\t\t\t\tSR400 Sunstar KC-401H Custom Type Disc Rotor Left and Right (Gold) KC-401H\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\n\t\t\t\t\t\t\t\t\t
\u30e2\u30c8\u30e1\u30ac\u30cd \u697d\u5929\u5e02\u5834\u5e97<\/div>\n\t\t\t\t\n\t\t\t\t\t\t\t\t\t
\n\t\t\t\t\t\t\u00a526,227\t\t\t\t\t\t\uff082026\/09\/21 13:36\u6642\u70b9 | \u697d\u5929\u5e02\u5834\u8abf\u3079\uff09<\/span>\n\t\t\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t
\n\t\t\t\t\t
\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\n\t\t\t\t\t\tAmazon\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t<\/div>\n\t\t\t\t\t\t\t
\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\n\t\t\t\t\t\tRakuten\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t
\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\n\t\t\t\t\t\tYahoo!\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t
\n\t\t\t\t\t\"\"\n\t\t\t\t\t\u30dd\u30c1\u30c3\u30d7<\/span>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t<\/div>\n\n\n\n
\t\t
\n\t\t\t\t\t\t\t
\n\t\t\t\t\t\n\t\t\t\t\t\t\"\"\/\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t
\n\t\t\t\t
\n\t\t\t\t\t\n\t\t\t\t\t\tSunstar chain & sprocket 3-piece set SR400 (520 convert) (88\u201321) with 1 extra chain joint, gold KS31707\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\n\t\t\t\t\t\t\t\t\t
\u30d0\u30a4\u30af\u3068\u30a2\u30a6\u30c8\u30c9\u30a2\u306e\u30a4\u30f3\u30c7\u30a3\u30fc\u30ba<\/div>\n\t\t\t\t\n\t\t\t\t\t\t\t\t\t
\n\t\t\t\t\t\t\u00a521,285\t\t\t\t\t\t\uff082026\/09\/21 13:36\u6642\u70b9 | \u697d\u5929\u5e02\u5834\u8abf\u3079\uff09<\/span>\n\t\t\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t
\n\t\t\t\t\t
\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\n\t\t\t\t\t\tAmazon\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t<\/div>\n\t\t\t\t\t\t\t
\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\n\t\t\t\t\t\tRakuten\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t\t
\n\t\t\t\t\t\t\t\t\n\t\t\t\t\t\n\t\t\t\t\t\tYahoo!\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t
\n\t\t\t\t\t\"\"\n\t\t\t\t\t\u30dd\u30c1\u30c3\u30d7<\/span>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t<\/div>\n<\/div>\n\n\n\n

<\/p>\n\n\n\n

<\/p>\n\n\n\n

<\/p>\n\n\n\n

<\/p>\n\n\n\n

<\/p>\n\n\n\n

Yamaha SR400 FI (Fuel-Injected Model).<\/span><\/div>
\n

Topic:<\/strong> 24-month statutory inspection & front brake upgrade with SUNSTAR Brake Disc Rotor<\/strong>. Details:<\/strong> Happy Thursday night from the Decoboco tech bay! For our second log tonight, we completed a thorough 24-month vehicle inspection on a fuel-injected SR400. Beyond routine fluid flushes and chassis greasing, we upgraded the worn front brake disc to a precision SUNSTAR rotor<\/strong>. SUNSTAR’s superior metallurgy and exact surface flatness eliminate rotor warpage, uneven pad wear, and lever pulsation. Combined with fully detailed caliper piston cleaning, fresh brake pads, and flushed DOT4 fluid, the brake feel is transformed. Verdict:<\/strong> The braking response delivers a deeply refined, progressive bite that perfectly matches the single-cylinder character. Routine inspections are the ideal opportunity to elevate your ride’s performance flavor!<\/p>\n<\/div><\/div>\n\n\n\n

<\/p>\n\n\n

<\/div>\n\n\n

<\/p>\n\n\n\n

\n
\n
\"\"<\/a><\/figure>\n\n\n\n

<\/p>\n<\/div>\n\n\n\n

\n
\"\"<\/a><\/figure>\n<\/div>\n<\/div>\n\n\n\n
<\/div>\n\n\n