NGK #3521 Spark Plug - Harley Milwaukee-Eight Touring & Softail
About NGK
NGK parts and accessories are stocked at Vtwinbikers for Harley-Davidson and Indian Motorcycle applications. Every NGK item we list is new and sourced through authorized distribution. If you are not certain a part matches your year and model, use Shop by Bike or email our team before you order and we will confirm fitment first.
The NGK #3521 spark plug is an OEM-quality replacement, crucial for maintaining optimal ignition in your Harley-Davidson or Indian Motorcycle V-twin. Manufactured in Japan, this plug ensures consistent and reliable performance for a wide range of engines. It's an essential component for routine maintenance or addressing ignition issues.
Why riders pick this
- Consistent ignition for V-twin engines
- OEM-quality replacement for reliable performance
- Precision manufactured in Japan by NGK
- Supports efficient combustion and engine health
Ensuring your V-twin has a strong, consistent spark is fundamental to its performance and longevity. The NGK #3521 spark plug is engineered to provide just that, offering a dependable ignition source for your Harley-Davidson or Indian Motorcycle. This plug is built to meet OEM specifications, guaranteeing a precise fit and reliable operation right out of the box.
Optimized for V-Twin Performance
- Delivers consistent ignition for efficient combustion
- Manufactured with OEM-equivalent construction for durability
- Genuine NGK quality, trusted by riders and shops
- Made in Japan for precision and reliability
Essential for Engine Health
Whether you're doing a routine service or chasing down an engine misfire, a fresh set of NGK spark plugs can make a significant difference. The #3521 is designed to integrate seamlessly into your V-twin, helping to restore power, improve throttle response, and maintain fuel efficiency. For riders with Milwaukee-Eight Touring or Softail models, this plug is a smart choice to keep your machine running strong. Always cross-reference with your motorcycle's specific requirements to ensure perfect compatibility.
Specifications
- Brand: NGK
- Manufacturer Part #: 3521
- UPC: 087295135211
- Length: 3.2 in
- Width: 1 in
- Height: 0.7 in
- Weight: 0.05 lbs
- Country of Origin: Japan
Common questions
What Harley-Davidson models does this spark plug fit?
This NGK #3521 spark plug is suitable for a range of Harley-Davidson Touring and Softail models with V-twin engines. Please confirm the specific year and engine type for your motorcycle using our Shop by Bike tool to ensure correct fitment.
Is this a genuine NGK part?
Yes, this is a genuine NGK spark plug, manufactured in Japan to meet OEM specifications for V-twin motorcycles.
Can I use alternative NGK spark plug numbers with this part?
Yes, ILKR8Q7 can be used as a direct substitute for ILKR8Q, and BPR8ES can be used in place of BPR8ES-S in compatible applications.
Ordering from Vtwinbikers
- Brand new, sourced through authorized US distribution — never used, never grey-market.
- Not sure it fits? Use Shop by Bike to filter by your year and model, or email us and we will confirm before you order.
- Harley-Davidson and Indian Motorcycle is all we do, so you are talking to people who ride what you ride.
| BRAND | NGK |
| TYPE | Spark Plugs |
| SKU | 2-CR9EIX |
| WEIGHT | 0.05 lb |
