Keith Black Pistons Std Flat Top Pistons KB258.STD for Big Twin 1984-1999
$566.15
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Keith Black Pistons Std Flat Top Pistons KB258.STD for Big Twin 1984-1999
$566.15
Upgrade your motorcycle's engine performance with Keith Black Pistons standard flat top pistons, engineered specifically for Harley-Davidson Big Twin Evolution engines. Crafted from a high-grade hypereutectic 16% silicon cast alloy, these pistons provide exceptional thermal stability and a low expansion rate, allowing for tighter piston-to-cylinder operating clearances in air-cooled applications.
Delivering an 8.6:1 compression ratio with standard 80cc combustion chambers, this piston set delivers durable reliability and smooth power output. The complete package includes two pistons, rings, wrist pins, and spiral locks to support a direct-fit OEM replacement.
Key Features
| Brand | Keith Black Pistons |
| Manufacturer Part Number | KB258.STD |
| Product Type | Engine Pistons |
| Piston Top Style | Flat Top |
| Bore Size | 88.8 mm |
| Stroke | 108 mm |
| Compression Ratio | 8.6:1 (with 80cc chamber volume) |
| Material | Hypereutectic Alloy (16% Silicon) |
| Replaces OEM Number | 21940-83 |
| Estimated Weight | 1.5 kg |
Highlights
- Engineered from 16% silicon hypereutectic alloy for low thermal expansion
- Ideal for air-cooled Big Twin Evolution motors
- Provides an 8.6:1 compression ratio with 80cc heads
- Direct replacement for OEM # 21940-83
Compatibility
Fits Harley-Davidson Big Twin Evolution (Evo) engine models from 1984 through 1999.
What's included
- 2 x Keith Black Hypereutectic Pistons
- 1 x Set of Piston Rings
- 2 x Wrist Pins
- 4 x Pin Retaining Clips
Downloads
Frequently asked questions
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