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Royal Enfield Interceptor 650 NGK Iridium Spark Plug Kit Review: Introduction

08 February 2021, 06:00 PM Vikrant Singh


Spark Plugs

What are Iridium spark plugs? Are they really an upgrade over the stocks ones? And finally are they worth the extra money? These are just some of the questions we intend answering in the course of this product review. 

Now we have gone for the complete NGK Iridium spark plug kit that includes low resistance or high tension lead cables or spark plug wires (call it what you will). There are new suppressor or resistor caps with improved insulation at both cap ends. And the ‘stars’ of this review – the Iridium IX spark plugs. The complete kit is sold specifically for the Royal Interceptor 650 by Ngage Powerparts in India and it costs Rs 4,500. If you just want the plugs, it should cost you just under Rs 800 a piece.

Iridium vs Stock

Spark Plugs

Iridium or stock – the difference is in the metal really. Your stock spark plugs use Copper and Nickel – Copper for better conductivity and Nickel to give the electrodes a chance to fight corrosion under fire breathing stress which is the combustion chamber. Iridium though is a more expensive metal. But it is also harder wearing and more resilient, if you will. 

Royal Enfield Interceptor 650

Royal Enfield Interceptor 650

  • Displacement648 cc
  • Mileage - Owner Reported23 kmpl
  • Max Power(bhp)47 bhp
  • Kerb Weight202 kg
  • ;

Avg. Ex-showroom price

₹ 2,88,166

And as we understand it, there are two reasons to pick an Iridium spark plug over your regular one – longevity and more consistent performance. Iridium spark plugs might also run hotter than stock ones. But then again, on a motorcycle like the Interceptor, it shouldn’t be an issue. In fact, as an added plus, this should help prevent fouling giving the plugs a longer life.

According to NGK, thanks to the plugs’ resistance to carbon fouling, these help return smoother running, better acceleration, and improved fuel efficiency. More importantly – at least in our book, and particularly for road bikes – consistent performance over time is as important as a bump up in performance. Which, thanks to its properties, an iridium spark plug should certainly deliver.

We will test this out, of course. And also keep a keen eye on any change in performance and fuel efficiency. But that’s for a later report.

High Tension Leads


NGK calls them racing spark cables. These are supposedly flame retardant and ultra low resistance cables. 

Now, we all understand how a spark plug works. Current flows from the ignition coil to the electrode via the spark plug cable. But, because a gap exists between the ground and the central electrode, a voltage difference begins to form. Eventually this difference becomes big enough to ionize the gas between the gap, and it begins to conduct. This then creates the spark jump. 

NGK says its low resistance cables improve the sparking energy. Which is understandable given a low resistance cable will allow more current to flow through it. And more the current for the same spark plug gap, means higher voltage generation. And that in turn means a more potent spark. This should also compensate for any relative loss of conductivity the Iridium spark plugs might have compared to the stock ones.

What’s next?

Spark Plugs

We will first switch the stock plugs, caps, and wires on the Interceptor with the NGK units. Then, we will pay close attention to the throttle response, the engine noise, the fuel efficiency, and the state of the plugs to see if there’s any change compared to the stock set. Finally, we will draw price comparisons and tell you if the NGK Spark Plug Kit is in fact a worthy upgrade or not…

Product Details

Make: NGK

Model: Iridium spark plugs, HT wires, suppressor caps

Sold by: Ngage Powerparts, Coimbatore

Price: Rs 4,500 (complete kit)

Photographs by Kaustubh Gandhi

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