Keith Black Pistons Flat Top Pistons KB258.020 for Big Twin 1984-1999
$566.15
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Keith Black Pistons Flat Top Pistons KB258.020 for Big Twin 1984-1999
$566.15
These Keith Black hypereutectic flat top pistons are engineered for Big Twin Evolution engines, featuring a cast 16% silicon alloy that delivers low thermal expansion for tighter piston-to-cylinder clearance. Designed specifically for air-cooled applications, they provide an 8.6:1 compression ratio with standard 80cc combustion chambers to ensure dependable, efficient power.
Supplied as a comprehensive engine set, each kit includes pistons, matching rings, wrist pins, and spiral locks. These components serve as direct performance replacements for OEM # 21943-83, ensuring a precise fit and reliable service life for your rebuild.
Key Features
| Brand | Keith Black Pistons |
| Product Type | Engine Pistons |
| Piston Top Style | Flat Top |
| Oversize | +0.020 in |
| Bore Size | 89.4 mm |
| Stroke | 108 mm |
| Material | Hypereutectic 16% Silicon Aluminum Alloy |
| Compression Ratio | 8.6:1 (with 80cc combustion chamber) |
| OEM Replacement Number | 21943-83 |
| Engine Compatibility | Air-Cooled Evolution (Evo) |
| Weight | 1.2 kg |
Highlights
- Cast hypereutectic 16% silicon alloy designed for air-cooled engines
- Low thermal expansion allows for tighter piston-to-cylinder clearance
- Provides an 8.6:1 compression ratio with 80cc cylinder heads
- Direct replacement for OEM # 21943-83
Compatibility
Fits Harley-Davidson Big Twin models from 1984 to 1999 equipped with the Evolution (Evo) engine.
What's included
- 2 x Keith Black Flat Top Pistons
- 1 x Piston Ring Set
- 2 x Wrist Pins
- 4 x Retaining Clips
Downloads
Frequently asked questions
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