Athena Big Bore Cylinder Kit 163.5cc - Honda CRF150R (2007-2010)

Race-Ready 163.5cc Big Bore Kit for CRF150R

Athena big bore cylinder kit transforms your CRF150R into a 163.5cc powerhouse. Complete race-spec kit with aluminum cylinder, forged piston, and gaskets—serious power gains for competitive racing.

Why Athena Big Bore Kits

✓ 163.5cc displacement (from 150cc)
✓ 69mm bore (oversized)
✓ Aluminum cylinder – nickel carbide coating
✓ Forged piston with moly coating
✓ Enlarged water jackets – better cooling
✓ Complete kit – cylinder, piston, gaskets
✓ Race-proven performance
✓ Professional-grade quality

What's Included

✓ Aluminum cylinder (69mm bore)
✓ Forged piston with molybdenum coating
✓ Rings, clips, wrist pin
✓ Complete Athena top end gasket set
✓ All required seals and hardware

⚠️ **Does NOT include cylinder head** (uses your OEM head)

Does It Fit?

✅ **Honda CRF150R** (2007-2010)

Quick Specs

Part #: P400210100023 / 0931-0307
Bore Size: 69.00mm
Displacement: 163.5cc (from 150cc)
Compression Ratio: 12.1:1
Cylinder: Aluminum with nickel-carbide coating
Piston: Forged with moly coating
Engine Type: 4-stroke
Weight: 3.14 lbs

Premium Cylinder Construction

**Nickel-Carbide Coating:**
Advanced cylinder coating for superior wear resistance and heat dissipation

**Enlarged Water Jackets:**
Improved cooling system design handles increased heat from larger displacement

**Aluminum Construction:**
Lightweight performance design

Forged Piston Technology

**Molybdenum Coating:**
Reduces friction and wear for longer life

**Forged Construction:**
Stronger than cast pistons—handles higher compression and heat

**12.1:1 Compression:**
High compression ratio for maximum power

Race-Ready Power Gains

**163.5cc vs. 150cc:**
13.5cc displacement increase delivers substantial power and torque gains throughout the powerband

**More Displacement = More Power:**
9% increase in displacement means serious horsepower gains for youth racing

Complete Top End Kit

**Everything Included:**
- Cylinder (69mm bore)
- Forged piston
- Rings, pin, clips
- Complete gasket set
- All seals
- All hardware

**Uses OEM cylinder head** (not included)

Installation Notes

⚙️ Difficulty: Advanced
🔧 Tools: Engine tools, torque wrench, measuring tools
🔧 Time: 4-6 hours
👨🔧 Professional installation highly recommended

Pro Tip

💡 When installing big bore kit, check all clearances carefully. Break in the engine properly—avoid high RPM and heavy loads for first few hours. Use quality oil and proper fuel mapping for the larger displacement.

What Else You'll Need

For installation:
- Engine oil and filter
- Coolant
- Fuel mapping/tuning (highly recommended)
- Valve service (check clearances)
- Timing chain inspection

Fuel Mapping Required

**Important:**
Big bore requires proper fuel mapping/ECU tuning for optimal air/fuel ratio. Stock mapping will run lean—dyno tune recommended.

Enhanced Cooling Design

**Larger Water Jackets:**
Athena redesigned cylinder with increased coolant capacity to handle extra heat from larger displacement

Why Go Big Bore

**More Power:**
Substantial increase in horsepower and torque

**Better Acceleration:**
More displacement = faster acceleration

**Competitive Edge:**
Stay competitive in youth racing classes

**Bolt-On Power:**
No other engine mods required

Uses OEM Cylinder Head

**Cost Savings:**
Reuses your OEM head—no need to buy expensive head

**Simple Install:**
Just replace cylinder and piston assembly

Perfect for Youth Racing

**Class Legal:**
Many youth racing classes allow up to 165cc displacement

**Competitive Advantage:**
Extra displacement keeps young riders competitive

Athena Quality

Athena is a world leader in 2-stroke and 4-stroke engine components. Their big bore kits are used by professional racers worldwide.

⚠️ California Prop 65 Warning

This product contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.

Questions?

📞 541-668-7503
📧 Support@dunegoonshop.info

Ships same day before 3pm EST ⚡
In stock - Ready to ship!