🔎 Why Does a 16T Feel Flat?

 That's a sharp observation, and you're absolutely right — changing to a 16T front sprocket can sometimes cause a flat power delivery if the internal gearbox ratios aren't ideal for that setup.

🔎 Why Does a 16T Feel Flat?

Your gearbox ratios determine how effectively power is transferred across each gear:

  1. Taller Gearing Effect:

    • Moving from 15T → 16T increases the overall gear ratio, reducing RPM at any given speed.
    • While this extends your top speed potential, it also demands more torque to maintain acceleration, especially in 5th and 6th gear.

  2. Gearbox Ratio Mismatch:

    • If your 1st - 4th gears are closely spaced (short-ratio design) but 5th - 6th gears are widely spaced, switching to 16T may create a "dead zone" where power flattens out.
    • Your engine’s revised power curve now builds peak power higher in the RPM range (~8,000 - 10,500 RPM), so taller gearing may prevent you from holding those higher RPMs effectively.

  3. Big Bore Impact:

    • Your 60mm bore setup produces more torque but may struggle with excessively tall gearing if the port timing and ignition advance don't deliver enough punch.

🔥 Recommended Solutions

Instead of a full jump to 16T, try one of these optimized options:

✅ Option 1: Keep 15T front but switch to a 31T rear sprocket

  • This achieves a milder gearing change, reducing the risk of feeling flat.
  • Expect a 2-3% RPM drop at high speeds without losing acceleration power.

✅ Option 2: If you still want to try 16T, use a 33T or 34T rear sprocket

  • This will regain some acceleration strength while still stretching your top-end performance.

✅ Option 3: Maintain your 15T/32T setup but focus on refining your ignition curve and carb jetting to increase acceleration torque.

🔎 Best Recommendation for Your Setup

Considering your current timing strategy, taller exhaust port, and goal to hit 200 km/h, I’d recommend starting with:

🔧 15T Front / 31T Rear → Best balance for acceleration and top speed.
🔧 Test 16T Front / 33T Rear only if you're confident your engine can sustain higher RPM without feeling flat.

🚨 Pro Tip for Testing

  • Use 4th gear as your test gear — it's the most neutral gear in terms of load and acceleration characteristics.
  • Accelerate from 5,000 RPM to 10,000 RPM and monitor how quickly your bike builds speed. If the bike struggles to pull effectively past 7,500 RPM, the gearing is likely too tall.

Would you like a detailed RPM-to-speed chart for different gear combinations to see how each setup will behave on the road? 🚀

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