Products Description
EY20 Generator Piston Assembly Kit | Complete Piston, Ring Set, Wrist Pin & Circlips for Robin-Subaru EY20 & EY15 4-Stroke Engines
OEM-Spec Aluminum Alloy Piston with 3-Ring Groove Profile, Molybdenum-Coated Compression Rings, 3-Piece Oil Control Ring Assembly & Hardened Chrome Wrist Pin
EY20 Generator Piston assy
The piston is gravity-cast or forged from a high-silicon aluminum alloy selected for its combination of light weight (reducing reciprocating mass and engine vibration), high thermal conductivity (transferring combustion heat to the cylinder wall and cooling fins), and controlled thermal expansion (maintaining correct piston-to-cylinder clearance across the engine's full operating temperature range). The piston crown is flat or slightly dished to match the EY20's compression ratio specification. Three ring grooves are precision-turned into the piston skirt: the top two grooves accept the compression rings that seal combustion pressure, and the third groove accepts the oil control ring assembly that scrapes excess oil off the cylinder wall and returns it to the crankcase through oil return holes drilled in the groove floor. A scored piston skirt - from running with low oil or ingesting dirt through a failed air filter - causes piston slap noise and accelerates cylinder bore wear. Replacing the complete piston assembly restores compression, oil control, and engine power to as-new specification.
Technical Profiles & Materials
High-Silicon Aluminum Alloy Piston：
The piston is manufactured from a eutectic or hypereutectic aluminum-silicon alloy, gravity-cast or forged to near-net shape, then CNC-machined at the ring grooves, wrist pin bore, and piston crown. The high silicon content (typically 11–18%) reduces the alloy's coefficient of thermal expansion, allowing tighter cold piston-to-cylinder clearances without the risk of seizure at operating temperature. This tight clearance reduces piston slap noise on cold start and improves ring sealing across the warm-up cycle.
5-Piece Ring Set ：
The ring set follows the standard small-engine configuration: (1) Top compression ring - typically a black molybdenum-coated or chrome-plated cast iron ring for high-temperature scuff resistance at the combustion seal. (2) Second compression ring - a black cast iron ring, often with a tapered or Napier-style lower edge that assists in scraping oil downward on the intake stroke. (3) Three-piece oil control ring - a brown corrugated steel expander spacer that presses two thin black steel rails outward against the cylinder wall.
Technical Specifications
| ITEM | DETAILS |
| Type | Complete Piston Assembly Kit - Piston + Rings + Wrist Pin + Circlips |
| Application | Robin-Subaru EY20 (182 cc) & EY15 (143 cc) 4-stroke OHV engines on generators, water pumps & pressure washers |
| Code | 1606084 |
| Material | High-silicon aluminum alloy piston, molybdenum/chrome cast iron compression rings, steel oil ring rails + corrugated expander, hardened steel wrist pin, spring steel circlips |
| Details explanation | Standard-size piston & ring kit. 3-ring groove profile. 5-piece ring set: 2 × compression + 3-piece oil control. Flat/dished crown. Complete kit: piston + ring set + wrist pin + 2 × circlips (red packet). |
| Brand Name | SeaSummer |
| Operating Temp | −20 ~ +300 °C (piston crown) |
| Delivery Time | 30 Days |
| Packaging | Cardboard packaging |
Products Application
Engine Machine Shop &
Rebuild Service Stock
For small-engine machine shops and rebuild services specializing in Robin-Subaru generators and industrial engines, stocking the EY20 standard-size piston assembly ensures rapid turnaround on the most common Robin engine rebuild. The standard bore size covers the majority of rebuilds - oversized pistons (+0.25 mm, +0.50 mm) are available for cylinders that have been bored to repair deep scoring, but the standard piston handles the typical ring-wear rebuild where the cylinder bore is still within service limits and requires only honing. The complete-kit format keeps all components organized and ready for the rebuilder, reducing bench time spent locating individual parts.
Low-Oil &
Dust-Ingestion Engine Repair
The two most common causes of piston failure on EY-series engines are running with low oil and dust ingestion through a failed air filter. Low oil causes the piston skirt to scuff against the cylinder wall, scoring both surfaces and generating metal debris that circulates through the engine. Dust ingestion - common on construction-site generators and water pumps operating in dry, dusty conditions - embeds silica particles in the piston rings and cylinder wall, accelerating wear. In both cases, the piston, rings, and wrist pin must be replaced. This kit provides all the components for the repair in one package, eliminating the risk of ordering the wrong ring set or forgetting circlips.
EY15 & EY20
Generator Engine Rebuilds
The primary application. Generators powered by Robin EY15 and EY20 engines accumulate hours rapidly during extended power outages, running at governed 3,000 or 3,600 RPM for 8–24 hours continuously. Over hundreds of hours, the piston rings wear, losing their outward spring tension against the cylinder wall. Compression drops, oil consumption rises, blue smoke appears from the exhaust, and the generator becomes progressively harder to start. Replacing the piston and rings - ideally paired with honing or deglazing the cylinder bore - restores compression, oil control, and the generator's ability to start reliably and carry its full rated electrical load.
Quality and Craftsmanship Details
Products Package
About Us
As a premier garden machinery parts supplier, Jiaxing Norsun Trading Co., Ltd. bridges global distributors with over 100 vetted China manufacturers. We streamline your B2B supply chain through strict quality control, flexible production, and factory-direct wholesale pricing. Partner with us for reliable, high-volume sourcing of precision-engineered outdoor power equipment components.
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YOUR PROFESSIONAL ONE-STOP SOURCE
FOR 10000+ OUALITY PARTS
Verified Factory Excellence
BACKED BY 200+ TRUSTED FACTORY PARTNERS
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FAQ
Q: Are you an impartial industrial components dealer or a direct China water pump factors factory?
A:We are a direct, ISO9001-certified engineering water pump components manufacturing facility and precision fluid-control factor manufacture exporter primarily based in China. We function our personal cleanroom injection molding bays, computerized ultrasonic welding arrays, computerized hydraulic stress check stations, and clean-room packaging lines, passing direct-factory wholesale price financial savings straight to your element procurement margins.
Q: Can your manufacturing unit furnish full certification forms for food-contact or consuming water compliance?
A: Yes, absolutely. For food, beverage, or scientific applications, our manufacturing unit makes use of one hundred percent virgin, un-recycled polypropylene resins accompanied by means of fabric traceability certificates. We mechanically furnish B2B purchasers with complete FDA compliance documentation, NSF-grade compound declarations, and RoHS/REACH chemical protection screening sheets to make certain clean clearance thru worldwide customs.
Q: Do you provide customization picks for distinctly corrosive fluids like sturdy acids or ozone?
A: Yes, we are a thoroughly succesful OEM/ODM supplier. For aggressive chemical or ozone environments, we can improve the 12x26.5mm valve configuration in our factory: substituting the general PP housing with top class PVDF (Fluoropolymer) and changing any steel springs with Hastelloy or whole springless gravity-ball architecture, making sure final chemical resistance.
Q: How do we impervious a pattern batch to execute computerized lifecycle and burst-pressure testing?
A: We relatively inspire complete laboratory contrast earlier than logging mass grant agreements. We can ship a pattern lot of 5-10 gadgets of our inventory 12x26.5mm take a look at valves for assessment (setup costs and DHL/FedEx air freight apply). Once the factors pass by your inner lifecycle verification and a formal wholesale quantity manufacturing contract or container run is locked in, the sampling charges are a hundred percent credited returned to your industrial balance.
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