KPMI 8-Piece Cylinder Stud Kit - Harley Milwaukee-Eight Touring & Softail
About KPMI
Kibblewhite Precision Machining supplies valves, valve springs, guides and complete top-end kits used by professional V-twin engine builders. Its black diamond valves and spring kits are a standard specification on high-lift cam builds.
Fortify your V-twin engine's top end with the KPMI 8-Piece Cylinder Stud Kit. These high-performance studs are manufactured from premium grade 8740 alloy steel, heat-treated to an impressive 180,000 psi yield strength. Crucially, the threads are rolled post-heat-treatment to maximize fatigue resistance and ensure consistent compressive stress at sustained high temperatures, vital for demanding Harley-Davidson and Indian Motorcycle applications.
Why riders pick this
- Grade 8740 alloy steel, 180,000 psi yield strength
- Threads rolled after heat-treat for superior fatigue life
- Interference fit design maintains thread contact at high temps
- Centerless ground for precision and concentricity
- Premium black oxide finish for corrosion resistance
When you're building a high-performance Harley-Davidson or Indian Motorcycle engine, cylinder head retention is paramount. The KPMI Cylinder Stud Kit provides the superior clamping force and durability needed to prevent head lifting, even under extreme combustion pressures. These studs are a critical upgrade for any V-twin running higher compression, forced induction, or aggressive cam profiles, ensuring the integrity of your engine's sealing surfaces.
Engineered for Ultimate Engine Integrity
- Manufactured from premium grade 8740 material, heat-treated to 180,000 psi yield strength
- Threads rolled after heat treating for maximum fatigue life and strength
- Slight interference fit design maintains optimal thread contact at high temperatures
- Centerless ground for exceptional concentricity and precision fitment
- Premium black oxide finish provides corrosion resistance and a clean look
The Foundation of a Strong Engine
A KPMI cylinder stud kit is an essential component for any serious V-twin engine build, providing a far more robust solution than factory bolts. The enhanced clamping force and superior material properties of these studs ensure cylinder head stability, preventing gasket leaks and maintaining peak performance. This 8-piece kit is designed for direct replacement, offering a significant upgrade in reliability and peace of mind for your Milwaukee-Eight Touring or Softail.
Specifications
- Brand: KPMI
- Manufacturer Part #: 20-21040
- Quantity: 8 studs per package
- Length: 5 in
- Width: 1 in
- Height: 1.4 in
- Weight: 8 lbs
Common questions
What material are these cylinder studs made from?
These KPMI cylinder studs are made from premium grade 8740 alloy steel, heat-treated to 180,000 psi yield strength, providing exceptional durability and resistance to stretching.
Why are the threads rolled after heat treating?
Rolling the threads after heat treating maximizes the fatigue resistance and tensile strength of the studs. This process retains compressive stress in the thread roots, which significantly extends their lifespan under high-stress engine conditions.
Will this 8-piece kit fit my Harley-Davidson Touring or Softail model?
This 8-piece cylinder stud kit is designed for Harley-Davidson Milwaukee-Eight Touring and Softail models. Please use our Shop by Bike tool to confirm exact fitment for your specific year and model before purchasing.
Ordering from Vtwinbikers
- Brand new, sourced through authorized US distribution — never used, never grey-market.
- Not sure it fits? Use Shop by Bike to filter by your year and model, or email us and we will confirm before you order.
- Harley-Davidson and Indian Motorcycle is all we do, so you are talking to people who ride what you ride.
| BRAND | KPMI |
| TYPE | Engine |
| SKU | 191-58018 |
| WEIGHT | 8.0 lb |
