Royal Enfield 1570400 / 1570400/B – Piston Ring (1st / Top Compression Ring) – J-Series 350 – Classic 350 Reborn, Meteor 350, Hunter 350, Bullet 350 – Genuine OEM

The Royal Enfield 1570400 / 1570400/B – RING-PISTON (1ST) is the genuine top compression ring for the new-gen J-Series 350 (349cc) engine used in the Classic 350 Reborn, Meteor 350, Hunter 350 and new Bullet 350. European OEM parts portals list 1570400/B as “SEGMENT 1ST 350”, confirming it as the factory 1st ring for 350 engines.  Multiple specialist sellers explicitly describe it as RING-PISTON (1ST) 1570400 for “All New Classic 350” and “Classic 350 / Meteor 350”, and as part of the standard piston ring kit 1570400/01/02 for Classic Reborn / Meteor / Hunter / Bullet 350. 

This ring is the top compression ring (1st ring)—the one that sees the highest pressure and temperature. Using the correct OEM ring is critical for proper compression, easy starting, strong low-end torque and long engine life. It is intended for standard bore cylinders and should be paired with the matching 2nd ring (1570401/B) and oil ring (1570402/B) when doing a full rebuild. 

Ideal for engine overhauls, de-glazing jobs, or restoring performance on high-mileage J-Series 350s, this genuine ring maintains the precise profile, material and tension that generic local rings often fail to match. If you want your Classic Reborn, Meteor, Hunter or Bullet 350 J-Series to feel like factory-fresh again, start with the right OEM top ring.

Key Features 

• Genuine Royal Enfield OEM piston ring – Part No. 1570400 / 1570400/B – RING-PISTON (1ST). 

• Designed as the 1st / top compression ring for J-Series 350 (349cc) engines. 

• Confirmed usage on All New Classic 350, Meteor 350, Hunter 350 & new Bullet 350 via multiple piston-ring kit and single-ring listings. 

• Correct standard size ring for stock bore; intended to be used with 1570401 (2nd ring) & 1570402 (oil ring) in a complete set. 

• Maintains factory compression ratio (≈9.5:1) and performance characteristics of the J-Series 350 engine. 

• OEM-spec metallurgy and ring tension for better sealing, reduced blow-by and controlled oil consumption.

• Helps restore power, throttle response and fuel efficiency on tired or overhauled engines.

• Manufactured to Royal Enfield tolerances – avoids the uneven wear and ring flutter common with cheap aftermarket sets.

• Supplied as a single 1st ring, perfect when only the top ring is damaged or when building an engine from separate OEM components.

• Backed by the reliability of authorised RE parts networks and international OEM distributors. 

Compatibility Table (Models, Engine Type, BS Stage, Years)

Core spec: 1st/top compression ring for Royal Enfield J-Series 350 (349cc, SOHC, air-oil cooled) engines. 

Not listed / ❌ (unconfirmed):

• Older UCE 350 & CI 350 models – Classic 350 UCE, Bullet 350 UCE, Electra, Thunderbird 350, cast-iron Bullets etc. use different piston and ring part numbers; do not treat 1570400 as compatible without checking the exact microfiche for that VIN.

• Other engines – 500 UCE, Himalayan 411, Guerrilla 450, Himalayan 450, 650 Twins, 535 GT etc. all use completely different pistons and rings.

🔴 No guesswork: Only the J-Series 349cc 350 models above are treated as confirmed based on multiple independent sources. Anything else = ❓ and must be verified on the official RE parts portal or with a dealer.

PLEASE PURCHASE ONLY AFTER VERYFING PART NUMBER

Variants

• Single Variant (this listing):

  • Part Number: 1570400 / 1570400/B

  • Type: Piston Ring – 1st / Top Compression Ring (Standard size)

  • Engine: J-Series 350 (349cc)

  • Contents: 1 × 1st compression ring only

(Full ring set usually consists of: 1570400 – 1st ring, 1570401 – 2nd ring, 1570402 – oil ring. Sold separately by most dealers.) 

FAQs 

Q1. Is 1570400 the full piston ring set or just one ring?
A. 1570400 / 1570400/B is the 1st (top) compression ring only. The 2nd ring and oil ring are separate part numbers 1570401/B and 1570402/B, and some sellers bundle them as a kit 1570400/01/02. 

Q2. Will this ring fit my Classic 350 Reborn / Meteor / Hunter / new Bullet 350?
A. Yes, this is the correct OEM 1st piston ring for the J-Series 350 engine used in Classic 350 Reborn, Meteor 350, Hunter 350 and the new Bullet 350, as confirmed by multiple OEM-parts and ring-set listings quoting 1570400/B and 1570400/01/02 for these models. 

Q3. Can I use 1570400 in my older UCE or cast-iron Bullet 350?
A. No, not by default. Older UCE and CI 350 engines use different piston & ring part numbers. 1570400/B is specified for the new 349cc J-Series platform only. If your bike is not a J-Series Classic/Meteor/Hunter/Bullet, you must check the RE microfiche or dealer before ordering.

Q4. Is this ring standard size or oversize?
A. All references (RE price list & OEM parts portals) list 1570400/B simply as RING-PISTON (1ST) with no oversize suffix, and it appears in standard piston-ring kits for J-Series 350. This listing should therefore be treated as standard bore J-Series 350. 

Q5. When should I replace the 1st ring?
A. Replace the 1st ring (and ideally the full set) whenever you:

• Re-bore or hone the cylinder

• Notice low compression, hard starting, oil consumption or blue smoke

• Tear down the top end after a seizure or serious overheating

Always check piston-to-bore clearance and ring end gap to factory spec during installation.