NGK BPR5EIX Iridium IX Spark Plug (6597) for Royal Enfield UCE 350/500 & Classic 350 BS6 – Genuine Upgrade

NGK BPR5EIX (Stock No. 6597) is an Iridium IX spark plug upgrade for cleaner ignition, smoother idle, and stronger consistency over long use.
Recommended by NGK’s India 2-wheeler application chart for multiple Royal Enfield UCE 350/500 models (see compatibility below).

DESCRIPTION

If your bike feels slightly “lazy” on pickup, idles rough, or starts taking extra cranks—many times the culprit is a tired plug and an enlarged gap. NGK BPR5EIX is an Iridium IX plug with a fine-wire iridium center tip (≈0.6 mm) designed to fire a stable spark with less voltage demand, helping improve cold starts, throttle crispness, and combustion consistency.

This plug is a popular upgrade over standard nickel/copper plugs because iridium resists wear better, so your gap stays stable longer (real-world life still depends on fuel quality, tuning, and riding style).

Critical fitment clarity (the part Amazon/Flipkart listings usually miss): BPR5EIX is a 14 mm thread, 19 mm reach, gasket-seat (flat seat), resistor plug, with factory gap typically listed as 0.8 mm for this model.

For Royal Enfield riders, NGK’s official India chart explicitly lists BPR5EIX for several UCE-era 350/500 applications (including Classic 350 BS6 UCE-era models in that chart). We’ve structured the compatibility below so you can avoid wrong ordering—especially on newer platforms where plug type may differ.

Sold by Under The Hood: genuine sourcing, careful packing, and pre-dispatch support if you share your current plug code / bike variant.

KEY FEATURES & BENEFITS

• Genuine NGK Spark Plug Co., Ltd. Iridium IX spark plug – Part BPR5EIX / Stock 6597

• Fine-wire iridium tip (~0.6 mm) for consistent spark and strong ignitability

• Resistor type (5kΩ) helps reduce electrical noise and supports stable running

• 14 mm thread + 19 mm reach + gasket seat (common spec used on listed RE applications)

• Helps with easier cold starts, smoother idle, and cleaner combustion when replacing a worn plug

• Trivalent plating for anti-corrosion / anti-seize shell protection

• Direct replacement for bikes that specify BPR5EIX (or same dimensions/heat range as per manual/NGK chart)

• Under The Hood support: share bike variant + old plug photo, we’ll help confirm before shipping

TECHNICAL SPECIFICATIONS

• Brand: NGK

• Part Number: BPR5EIX

• NGK Stock Number: 6597

• Series / Type: Iridium IX

• Thread Diameter / Pitch: 14 mm / 1.25 mm

• Reach: 19 mm (3/4")

• Seat Type: Flat seat with gasket (crush washer)

• Hex Size: 20.8 mm (13/16")

• Heat Range: 5 (NGK scale)

• Resistor: Yes (5kΩ)

• Factory Gap: 0.8 mm (listed by multiple retailers for 6597)

• Center Electrode: Iridium fine wire (~0.6 mm)

• Country of Origin: — not clearly specified consistently in reliable official sources in the pages retrieved (avoid guessing)

COMPATIBILITY SECTION

a) Confirmed Compatible Models (from NGK India 2W Iridium application chart)

*NGK chart doesn’t provide exact year ranges; verify by platform (UCE vs newer platforms) before ordering.

ONLY FOR UCE MODEL 

Not Compatible / Common Confusion

• Do not buy only 1 plug for UCE Twin-Spark models if your bike requires the 2-plug combination (BPR5EIX + CPR6EAIX-9S) as shown in NGK’s chart.

VARIANTS 

Recommended Shopify variants (high-conversion):

• Single Plug (1 pc) – for bikes that use only BPR5EIX (or for replacing one plug).

• Twin Spark Set (2 plugs) – for UCE twin-spark bikes that need the combo BPR5EIX + CPR6EAIX-9S

WHAT’S IN THE BOX

• 1 × NGK BPR5EIX (6597) Iridium IX Spark Plug
  (No extra washers/boots/tools included.)

INSTALLATION & MAINTENANCE NOTES

• Install on a cool engine; start threads by hand to avoid cross-threading.

• Do not aggressively re-gap iridium fine-wire plugs—if you must verify gap, do it carefully without prying on the iridium tip.

• Use correct torque for gasket-seat plugs; over-tightening can damage threads/head. (If you need exact torque for your model, follow service manual.)

• If your bike is twin-spark UCE: confirm whether it needs the 2-plug set shown by NGK chart.

FAQ

1) Will NGK BPR5EIX fit my Royal Enfield Classic 350?
It is listed in NGK India’s 2W Iridium chart for Classic 350 (BS6 as listed) and also for several UCE 350/500 applications. Use the compatibility table above and confirm your platform.

2) My bike is UCE Twin Spark—do I need 1 plug or 2 plugs?
Many UCE twin-spark setups require two different plugs. NGK’s chart shows BPR5EIX + CPR6EAIX-9S for certain UCE 350/500 twin-spark applications.

3) Is this an upgrade over the regular BPR5ES / standard plug?
Yes—BPR5EIX is Iridium IX with a fine-wire iridium center electrode designed for stable spark and longer consistency vs standard nickel plugs (maintenance still matters).

4) What are the key specs of BPR5EIX (6597)?
14 mm thread, 19 mm reach, gasket seat, resistor type, heat range 5, factory gap typically listed as 0.8 mm.

5) Will this improve mileage?
A fresh, correct plug can restore smooth combustion if your old plug was weak/fouled. Mileage depends more on tuning, riding style, air filter, fuel quality, and tyre pressure—so don’t expect miracles.

6) My bike is Classic 350 Reborn (J-Series). Will this fit?
Not confirmed from the NGK chart lines we cited. Best method: match your existing plug code / manual. If you share a plug photo, we’ll help you verify before dispatch.

7) Do I need to change plug cap / ignition coil?
Usually no, unless the cap/coil is cracked or misfiring. If you still have misfire after plug change, inspect cap, HT lead, coil, and fuel/air systems.

8) Is this genuine NGK? How do I avoid fake plugs?
Buy from a trusted store, check packaging, print quality, and plug markings. Under The Hood sources through reliable channels and packs to avoid damage in transit.