Automotive / Performance Kits
Installation Manual for HKS BCD Piston Kit 21003-AT006
Comprehensive installation guide for the HKS BCD Piston Kit (21003-AT006) for G16E engines. Includes technical specifications, clearance verification, ring installation, and maintenance procedures.
Quick answers from the manual
Quick answer
- This manual provides installation instructions for the HKS BCD Piston Kit (21003-AT006) for G16E engines, including clearance specifications, ring installation, and maintenance intervals. p. 1, 13
Key actions
- Verify piston clearance (0.029-0.054 mm) and ring gap clearances before final assembly. p. 5, 7, 16, 17
- Ensure the piston front mark (indent) faces the front of the engine. p. 10, 20
First start
- Check for oil/water leaks, ensure hoses are not twisted, and verify oil level is between H and L. p. 10, 20
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Problems and fixes
Oil or water leakage
Do not start the engine; consult a professional.
p. 12, 21Maintenance and reset
- Replace engine oil every 3,000 km or every 6 months. p. 11, 20
Technical specifications
| Parameter | Value | Meaning | Pages |
|---|---|---|---|
| Piston Clearance | 0.029-0.054 mm | Designated clearance value | p. 5, 16 |
| Compression Ring No.1 Clearance | 0.160-0.185 mm | Designated clearance | p. 7, 17 |
| Connecting Rod Small End Oil Clearance | 0.003-0.012 mm | Designated clearance | p. 9, 19 |
Where to find it in the PDF
- Installation Instructions p. 5, 6, 7, 8
Table of contents
Manual images
Click an image to enlargeQuick guide from the manual
This document provides installation and maintenance instructions for the HKS BCD Piston Kit (21003-AT006). Installation must be performed by a professional. Before starting, ensure the engine bay has cooled to approximately 40°C (104°F) to prevent burns. Always use the factory service manual for removing and installing factory parts.
Safety Precautions
- Explosion/Fire Prevention: Work in a well-ventilated area and handle flammable objects with care.
- Electrical Safety: Disconnect the negative battery terminal before beginning work.
- Jacking: Use wheel blocks and jack stands; never work under a vehicle supported only by a jack.
- Leakage: Do not start the engine if oil or water leakage is detected.
Installation Procedures
Clearance Verification
The piston kit is designed for stock bore sizes. Boring and honing are generally not required, but verify clearances:
- Piston Skirt O.D.: 87.450 to 87.460 mm.
- Piston Clearance: 0.029 to 0.054 mm.
- Measurement: Measure 12 mm above the bottom of the piston skirt at 20°C.
Cylinder Bore Chamfering
If burrs exist on the cylinder bore bottom edge, file them off using #600 or equivalent sandpaper. The chamfering volume should be R2 or more. Do not over-chamfer.
Piston Ring Installation
Adjust ring opening clearance to the following specifications:
- Compression Ring No.1 (C1): 0.160–0.185 mm.
- Compression Ring No.2 (C2): 0.760–0.810 mm.
- Oil Ring Expander: 0.100–0.350 mm.
Ensure C1 < C2 to reduce oil consumption. Use a piston ring expander for installation and ensure the orientation (T/2T marks) is correct.
Connecting Rod Small End Oil Clearance
Calculate clearance by subtracting the piston pin O.D. from the conrod small end I.D. The designated clearance is 0.003–0.012 mm.
Assembly
The piston features a front mark (indent). Ensure this mark faces the front of the engine during assembly to avoid interference with the oil jet.
Maintenance
Proper maintenance is essential for safety and performance:
- Oil Changes: Replace engine oil every 3,000 km or every 6 months.
- Filter Replacement: Replace air filters every 3,000–5,000 km or every 3–6 months.
- Break-in: Perform break-in driving for 1,000–3,000 km after crank metal replacement.
Manufacturer information
HKS Co., Ltd.
Practical help
Common problems
Oil or water leakage
Do not start the engine. Consult a professional immediately to identify the source and repair.
Abnormal drop in oil pressure
Stop driving immediately. Do not restart the engine. Have the vehicle inspected by a professional.
Excessive oil consumption
Verify that piston ring clearance C1 C2, oil consumption will increase significantly.
Before use
- Ensure engine bay temperature is cooled to approx 40°C
- Verify all parts listed in the Parts List are present
- Have the factory service manual available
- Use proper tools for tightening bolts and nuts
- Mark positions of removed factory parts for reinstallation
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Specs in practice
- Piston Clearance
- 0.029-0.054 mm; critical for engine performance and preventing damage.
- Compression Ring No.1 Clearance
- 0.160-0.185 mm; must be smaller than No.2 ring clearance.
- Connecting Rod Small End Oil Clearance
- 0.003-0.012 mm; ensures proper oil film.
Images and diagrams
- Figure 1: Piston skirt measurement point (12mm from bottom)
- Figure 3: Measuring piston ring clearance with a thickness gauge
- Figure 7: Piston ring gap positioning to prevent overlap
- Figure 10: Front mark identification on the piston
Model compatibility
- Designed for TOYOTA GR Yaris (4BA-GXPA16) and GR Corolla (4BA-GZEA14H) with G16E-GTS engine.
- Requires HKS Connecting Rod Set STEP3 (23004-AT003).
Manual page author
David Miller
Documentation analyst