Athena Big Bore Cylinder Kit 144cc - Kawasaki KX125 (2003-2007)
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Race-Ready 144cc Big Bore Kit for KX125
Athena big bore cylinder kit transforms your KX125 into a 144cc powerhouse. Complete race-spec kit with aluminum cylinder, high-performance power valves, piston kit, and gaskets—everything for serious power gains.
Why Athena Big Bore Kits
✓ 144cc displacement (from 125cc)
✓ 58mm bore (oversized)
✓ Aluminum cylinder – nickel carbide coating
✓ High-performance power valves included
✓ Complete kit – cylinder, piston, gaskets
✓ Race-proven performance
✓ Professional-grade quality
What's Included
✓ Aluminum cylinder (58mm bore)
✓ Aluminum cylinder head (removable bronze dome)
✓ High-performance anodized power valves
✓ Cast lite flat-top piston
✓ Rings, clips, wrist pin
✓ Complete Athena top end gasket set
✓ All required seals and hardware
Does It Fit?
✅ **Kawasaki KX125** (2003-2007)
Quick Specs
Part #: P400250100011 / 0931-0109
Bore Size: 58.00mm
Displacement: 144cc (from 125cc)
Cylinder: Aluminum with nickel-carbide coating
Head: Aluminum with removable bronze dome
Piston: Cast lite flat-top
Engine Type: 2-stroke
Weight: 5.62 lbs
Premium Cylinder Construction
**Nickel-Carbide Coating:**
Advanced cylinder coating for superior wear resistance and heat dissipation
**Aluminum Cylinder:**
Lightweight performance construction
**Bronze Dome Head:**
Removable dome allows compression tuning
High-Performance Power Valves
**Specially Designed:**
Hard anodized power valves engineered for big bore performance
⚠️ **Important:** Cannot use OEM power valves—must use included Athena valves
Race-Ready Power Gains
**144cc vs. 125cc:**
19cc displacement increase delivers substantial power and torque gains throughout the powerband
**More Displacement = More Power:**
Bigger bore means more fuel/air mixture per cycle
Complete Top End Kit
**Everything Included:**
- Cylinder and head
- Power valves
- Piston kit (piston, rings, pin, clips)
- Complete gasket set
- All seals
- All hard
📦 Shipping Information
In-stock items ship next business day. ModQuad parts dispatch Monday through Thursday.
Made-to-order and custom powder coat items show their lead time at the top of this page, right next to the truck icon. These are built fresh for you, so timing varies by brand and current backlog.
Need something by a specific date? Call us at 541-668-7503 before ordering and we will check stock and ETA on that exact part. We can often point you to an in-stock alternative from another distributor.
Questions? Contact us, we respond within 24 hours.
