Royal Enfield 145406/A Front / Final Drive Sprocket 17T – 500cc 4-Speed Bullet & Lightning (After Aug 2001) – Genuine OE

Royal Enfield part 145406/A is the genuine front / final drive sprocket 17T for classic 500cc 4-speed Bullets and Lightning models manufactured after August 2001. Official microfiche and price lists describe it as “FRONT DRIVE SPROCKET 500CC”, confirming its OE use on 500cc gearboxes. Multiple specialist dealers list this sprocket as the correct 17-tooth gearbox sprocket for Bullet 500 and Lightning 500/535 4-speed models, with 145406/A specified for 500cc machines built after the August 2001 cut-off. 

As the primary final drive sprocket on the gearbox output shaft, this part directly affects chain alignment, acceleration and cruising RPM. A worn or hooked sprocket can eat chains and cause vibration; replacing it with a genuine Royal Enfield sprocket restores smooth drive and correct tooth profile. This 17T size is the standard gearing on many 500cc 4-speed Bullets and Lightning models, giving a good balance of low-end pull and comfortable highway cruising. 

Manufactured to OE specification for spline fit, hardness and tooth form, 145406/A is a better long-term choice than cheap “as per photo” copies. Many aftermarket sprockets are sold generically for “all Bullets”, but this kit is specifically engineered for 500cc 4-speed gearboxes and replaces earlier part 111189 on post-Aug-2001 machines. For best results, install with a healthy chain and correct tension.

Key Features 

• Genuine Royal Enfield front / final drive sprocket – Part No. 145406/A 

• 17-tooth gearbox sprocket for 500cc 4-speed Royal Enfield models 

• Specifically referenced for 500cc models manufactured after Aug 2001, replacing earlier 111189 sprocket on older bikes.

• Confirmed fitment for Bullet 500 and Lightning 500 / Lightning 535 4-speed models via multiple dealer catalogs 

• OE-grade material and heat treatment for long life and correct tooth profile

• Precise spline and bore machining for tight, wobble-free fit on the gearbox mainshaft

• Helps restore smooth power delivery, reduces chain snatch and uneven wear

• Ideal for full transmission refresh or gearing service on classic 500cc Bullets

• Much more reliable than low-cost “universal” sprockets that can misalign the chain

Compatibility Table 

CHECK PART NUMBER BEFORE PURCHASE 

Not compatible with:

• 350cc Bullets (different stock gearing and part numbers)

• UCE generation (Classic 500 EFI, Bullet 500 UCE, etc.)

• 5-speed AVL / later gearboxes

• J-Series, Himalayan, Twins or any modern RE platforms

Variants:

• Single variant only:

  • Royal Enfield 145406/A – Front / Final Drive Sprocket 17T – 500cc

• Cross-reference: replaces earlier 17T sprocket part 111189 on many machines when manufactured after Aug 2001. 

FAQs 

1. Will 145406/A fit my Bullet 350 or Classic 350?
   No. Part 145406/A is specifically referenced for 500cc 4-speed Royal Enfield models. 350cc Bullets use different standard gearing and part numbers, so this sprocket is not recommended for them.

2. What is the tooth count of this sprocket?
   This is a 17-tooth (17T) front / gearbox sprocket, as confirmed by multiple listings describing it as “Final Drive Sprocket – 17T” for Royal Enfield. 

3. What’s the difference between 145406/A and 111189?
   111189 is an earlier 17T final drive sprocket used on many 500cc models before August 2001. For Royal Enfield 500cc models manufactured after August 2001, suppliers explicitly direct customers to use 145406/A instead.

4. Does this fit UCE or EFI 500 models?
   No. This sprocket is for pre-UCE, 4-speed gearboxes. UCE / EFI models use a completely different transmission and require different sprockets.

5. Do I need to change the chain and rear sprocket at the same time?
   It’s strongly recommended. Replacing only the front sprocket on a worn chain and rear sprocket can accelerate wear. For best life and smooth running, change front sprocket, rear sprocket and chain as a set.