Product Description
Ride with confidence using the KB PERFORMANCE PISTON KIT M8 128″ STD from Knobtown Cycle.
Key Features
- Updates stock 107″, 114” or 117” motor to 124” or 128” when using 4.250” big bore cylinders
- Valve pockets are designed to accept up to +4.00 mm oversized intake and exhaust valves
- Type 3 hard-anodized crown offers corrosion resistance for alcohol-added fuels
- Type 3 hard-anodized top ring groove eliminates micro-welding of ring to the groove and gives a hard-flat surface for ring to rotate on
- OE-style round wire locks are easily installed
- Heavy-duty wrist pins with true 0.9270” diameter to fit rods correctly
- Line2Line AST skirt coating starts out with a near-zero wall clearance and through the break-in period hones the cylinders to produce the correct oil wedge, keeping the piston square to the cylinder for best ring seal and quiet operation
- Kit includes pistons, rings, pins and locks
- Requires 4.250″ bore cylinder sold separately.
Product Specifications
- Part Number: 09106405
- Brand: KB PERFORMANCE
- Weight: 3.15 lbs
- UPC: 800745276186
Professional Installation Available
Buy online or visit our Kansas City showroom. Contact us for installation service options! Free Ship to Store!
Part Locations
| Location |
Available |
| Wisconsin (WI) |
0 |
| New York (NY) |
1 |
| Texas (TX) |
0 |
| Nevada (NV) |
0 |
| North Carolina (NC) |
1 |
| National Total |
2 |
Stock levels last updated: January 30, 2026 8:09 PM
Professional Installation Available
Knobtown Cycle offers professional installation services. Contact us via a service request to learn more.
Thank you for Shopping at Knobtown Cycle!
When you shop with us, you’re not just buying motorcycle parts — you’re supporting a small, family-run business rooted right here in the heartland of America. Every order helps us keep riders on the road and fuels our passion for serving the motorcycle community.
From all of us at Knobtown Cycle, thank you for choosing local and riding with us.
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