Max Trading proudly presents the Motorcycle Piston Set for Honda XR250, specifically developed for this iconic model. We offer not only the standard 73mm size but also +25 and +50 repair sizes to accommodate cylinder wear. Utilizing micro-arc oxidation and T6/T7 heat treatment processes,
To address the high thermal load of the 250cc four-stroke engine, our Motorcycle Piston Set for Honda XR250 features significant advancements in materials and design:
Our pistons are made from tin-plated aluminum alloy castings and undergo complex solution strengthening (T6) and artificial aging treatment. This process, comparable to steel quenching, greatly enhances the material's mechanical strength. Some high-end batches even incorporate T7 quenching and tempering processes to ensure the piston does not undergo physical deformation under extreme high pressure.
Thermal Barrier Technology: The piston crown is treated with micro-arc oxidation, forming a ceramic-like protective film that effectively resists high combustion chamber temperatures, preventing ablation at high RPMs.
Oval/Barrel-Shaped Skirt: To compensate for thermal expansion, the skirt is precisely machined into an oval or barrel shape, combined with a 0.5mm offset pinhole design, perfectly solving the problems of impact noise and side wall wear caused by piston oscillation in the cylinder.
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Specifications |
Details |
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Cylinder Diameter |
Standard: 73mm; Additional options (based on cylinder wear): +25 (0.25mm increase) and +50 (0.50mm increase) piston ring components |
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Piston Pin Diameter |
Pin hole diameter: usually 17mm; Pin length: about 54mm |
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Temperature Requirement |
Continuous operating temperature ≤ 300℃ (to avoid high-temperature sintering) |
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Compression Ratio |
Some piston kits: 10.5:1; Others: 10:1 (e.g., piston kit for 79-82 model year XR250 with 75mm cylinder diameter) |
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Piston Rings - End Clearance |
1st ring: 0.4-0.6mm (larger due to high operating temperature); Other rings: 0.20-0.40mm |
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Piston Rings - Side Clearance |
Usually 0.025-0.04mm; Too large: affects sealing effect; Too small: risk of piston ring getting stuck in ring groove after thermal expansion |
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Piston Rings - Back Clearance |
Generally 0.35-0.55mm |
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Piston Rings - Number of Grooves |
Commonly 3-ring structure; May vary by model |
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Suitable Models |
Mainly for Honda XR250R and XR250L motorcycles |
Q1: Why is the gap in your 1st piston ring larger than typical pistons?
A: This 0.4-0.6mm gap is specifically designed to accommodate the high-temperature operating environment of the XR250. This prevents the piston ring from seizing due to thermal expansion, avoiding serious damage.
Q2: How can I differentiate between XR250 pistons from different years?
A: The main differences are in the bore diameter and compression ratio. For example, 79-82 models commonly have a 75mm bore. Our technical team can provide precise recommendations based on your VIN code or original part dimensions.
Q3: What is the function of the tin plating on the piston surface?
A: The tin plating acts as a lubricant during the initial break-in period, effectively preventing dry friction during the initial installation of the new piston and ensuring the motorcycle piston assembly smoothly enters its optimal operating state.
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