Keith Black flat top piston set is .030 oversize with an 8.6:1 compression ratio for 1984-up Big Twin Evolution models.
The Keith Black 390 hypereutectic alloy is cast in a permanent steel mold which makes it possible to build a light weight piston that makes more power and uses less fuel and lasts longer. Pistons are .030 over sized for a 3.498 bore and has a 8.5:1 compression ratio. The low heat transfer of the alloy keeps the skirts cool so piston expansion is minimal. The combination of a low heat transfer piston alloy and high compression ring placement increases power and economy. The high ring placement alone reduces detonation and increases the top ring temperature. **Note:Run engine at moderate speeds for at least 500 miles avoiding excessive running in lower gears in order to properly break-in new pistons and rings.
Fits:
FLST 1986-1998
FLT 1984-1998
FXD 1991-1998
FXR 1984-1994
FXST 1984-1998
UOM: SET
Country Of Origin: MEXICO
Suggested Items: 11-1366 - 80 Shovelhead Piston Ring Set .030
Accessory Items:
16-0622 - Ring-O-Matic Ring Compressor Tool Kit
60-0167 - Cylinder Boring Service
16-0075 - Wrist Pin Ring Tool
Keith Black flat top piston set is .030 oversize with an 8.6:1 compression ratio for 1984-up Big Twin Evolution models.
The Keith Black 390 hypereutectic alloy is cast in a permanent steel mold which makes it possible to build a light weight piston that makes more power and uses less fuel and lasts longer. Pistons are .030 over sized for a 3.498 bore and has a 8.5:1 compression ratio. The low heat transfer of the alloy keeps the skirts cool so piston expansion is minimal. The combination of a low heat transfer piston alloy and high compression ring placement increases power and economy. The high ring placement alone reduces detonation and increases the top ring temperature. **Note:Run engine at moderate speeds for at least 500
