Kawasaki Ninja 400 & Ninja 500 mods & upgrades

The Ninja 400 is the budget track weapon of its era — the backbone of lightweight racing grids and the bike whole race-parts catalogs (Spears Racing, Norton Motorsports) are built around. Stock it's a friendly beginner bike; the aftermarket turns it into a corner-speed scalpel.

1. Tail tidy

   The stock fender is the biggest visual offender on the bike. A fender eliminator with LED signals is the universal first mod.

   Tail Tidy & Billet

2. Sliders and spools

   Frame sliders, swingarm spools, maybe case covers. New riders drop bikes; a $150 kit keeps a tip-over cosmetic.

   Crash Protection

3. Slip-on exhaust

   Yoshimura, Akrapovič and LeoVince own the fitment. It's for sound and shedding the anchor of a stock can — power stays basically stock, and no codes are thrown.

   Exhaust

4. Levers and grips

   Adjustable levers fix the long reach for smaller hands — a real ergonomic fix on this bike, not jewelry.

   LeversClip-ons & Throttle

5. Springs for your weight

   The stock suspension is built to a price and sprung soft. Fork springs and a shock spring (or budget shock) matched to your weight transform it more than any engine part could.

   Suspension

6. Windscreen

   A taller Zero Gravity or Puig screen gives taller riders somewhere to hide. Cheap and reversible.

   Bodywork

1. Tires

   The 400 carries corner speed all day — sticky rubber in stock sizes (Supercorsa, Q5) is the first and biggest lap-time purchase. Warmers only once you're consistently quick.

   Tires & Wheels

2. Quick-turn throttle and grips

   The stock throttle throw is famously long — a quick-turn throttle (Domino XM2 style, or race kits from the N400 specialists) is the beloved cheap fix. Tank grips at the same time.

   Clip-ons & Throttle

3. Suspension, the real spend

   Fork cartridge kit or springs-and-valving plus a proper shock (Öhlins, K-Tech, Nitron — or the community's GSX-R shock swap on a budget). This is where a race-pace Ninja 400 is actually made.

   Suspension

4. Brake pads and lines

   The single front disc works fine at this weight once you feed it sintered pads, a braided line and fresh fluid. Master-cylinder upgrades are racer territory.

   Brakes

5. Make it crashable

   Case covers, race bodywork, clip-ons and rearsets from the race catalogs. Lightweight-class crashes are usually slow — a prepared 400 gets picked up and finishes the day.

   Crash ProtectionBodyworkRearsets

6. Gearing and fueling

   Sprocket changes wake the little twin up more than any pipe; a full system plus ECU flash is the last step and the only real power there is to find.

   DrivetrainExhaustTune

• EX400G/H2018–2023

  One generation, start to finish: 399 cc twin, steel trellis frame, EX400G with ABS and EX400H without. Colors and KRT graphics changed yearly; the hardware didn't — which is why parts listed "2018–2020" almost always fit through 2023 (verify with the seller).

• EX500 (Ninja 500)2024–present

  Successor, not a Ninja 400: the 451 cc engine is a stroked evolution on largely the same chassis. Community-reported that many 400 parts carry over, but fitment is being confirmed part-by-part — don't assume.