The NAMURA NA-10040K Top End Kit is a standard-bore, 11:1 compression replacement kit designed for select Honda Rancher all-terrain vehicles. This complete top-end assembly includes a piston, piston rings, wrist pin, wrist-pin clips, top-end bearing, and gasket kit, providing the primary components needed for a reliable engine rebuild. The kit is engineered for a proper fit on 2004–2007 Honda TRX400FA Rancher AT models with SRA and 2004–2007 Honda TRX400FGA Rancher AT GPScape models with SRA.
The piston uses NAMURA's MOS2, or Teflon/Molybdenum, coated skirts. This rolled-on coating process creates a durable bond intended to reduce friction, improve heat transfer, and help minimize the risk of cold seizures during operation. Machined smooth heads help reflect combustion heat and reduce carbon buildup on the piston crown, supporting consistent performance and protecting the piston during demanding riding conditions.
Anodized domes provide enhanced heat resistance and durability, while the hypereutectic casting process increases silicon content to help control expansion and improve wear resistance. These features allow the piston to withstand elevated cylinder temperatures while maintaining dependable operation. The NAMURA NA-10040K is a practical choice for restoring compression and renewing the top end of compatible Honda Rancher engines. Verify the vehicle model, year, standard-bore application, and compression specification before installation.
Features:
- Complete top-end kit includes piston, rings, wrist pin, wrist-pin clips, top-end bearing, and gasket kit
- Standard-bore piston with an 11:1 compression ratio for compatible Honda Rancher applications
- MOS2 Teflon/Molybdenum coated skirts help reduce friction, improve heat transfer, and minimize cold-seizure risk
- Machined smooth piston heads help reflect combustion heat and reduce carbon buildup
- Anodized domes improve heat resistance and piston durability
- Hypereutectic casting process provides controlled expansion and improved wear resistance
- Fits 2004–2007 Honda TRX400FA Rancher AT with SRA
- Fits 2004–2007 Honda TRX400FGA Rancher AT GPScape with SRA
- Brand: NAMURA
- Manufacturer part number: NA-10040K
- Vendor part number: 186-1040
Fitment:
2004 Honda TRX400FA Rancher AT [SRA]
2004 Honda TRX400FGA Rancher AT GPScape [SRA]
2005 Honda TRX400FA Rancher AT [SRA]
2005 Honda TRX400FGA Rancher AT GPScape [SRA]
2006 Honda TRX400FA Rancher AT [SRA]
2006 Honda TRX400FGA Rancher AT GPScape [SRA]
2007 Honda TRX400FA Rancher AT [SRA]
2007 Honda TRX400FGA Rancher AT GPScape [SRA]