This listing is for FOUR (4) NEW DENSO IRIDIUM POWER spark plugs - IY27.  These are an upgrade to the standard Y27FER-C spark plugs.  Made in Japan.

Iridium Power in Moto GP video: www.youtube.com/watch?v=tlavyU1sgZI

Denso Racing: www.youtube.com/watch?v=KrPwVTCH_oQ


Fitment for Honda models:

400cc: VFR 400 R / -R III (NC30) 1990-> Y27FER-C 4162 IY27 5401 0.7mm gap


400cc: RVF 400 (NC35) 44 Y27FER-C 4162 IY27 5401 0.6mm gap


Denso fitment check: www.denso-am.eu/e-catalogue 

Feel free to 'Ask a Question' if unsure of fitment for your bike. 

 

NGK ER9EH replacement (a standard NGK fitment check is available on - www.ngkpartfinder.co.uk/catalogues/motorcycles/)

 

Reviews from previous buyers that have purchased Denso spark plugs from Bell Rock Racing:

 

Honda NC30 supplied with Denso Y27FER-C plugs.

  

The plugs that you supplied last year have done well.  They were fitted
into a standard NC30 that I prepped for another team.  It's done a
Southern 100, a couple of club meetings and a 4hr endurance race and
still seem to be fine. They didn't miss a beat.  I had the bike back for
a pre-season check over and the team said they're happy just to leave
the plugs in till later in this season.
That left me using the NGK's I had already in my supply box.  They were
fitted at the beginning of the Manx Grand Prix and one failed on me in
the last practice session. (I wish I hadn't used the Denso's on the
other teams’ bike).  It cost me a packet to get a set at the paddock ready
for the race the next day AND they were NGK.
Anyway, we've gone for broke for this year.  We've had the engine tuned
by Slick Bass (Carl Fogarty's mechanic when he was SBK champion with
Ducati).  He wants us to use the standard Denso Y27FER-C plugs in the front 2 cylinders and the Denso Y31FER-C in the rears due to them running hotter.


Thanks again for your help.

 

 

John Harrison, Douglas, Isle of Man. 

 

Structure

Structure

1Specifications Include Terminal
A terminal nut is attached that fits with most of the world’s spark plug cables. Please remove the nut for installations that do not require one. (The terminal nuts on the IWM and IK-G types are solid parts and cannot be removed.)
2Built-in, Highly Reliable Resistor
All IRIDIUM POWER plugs include a highly reliable, 5,000 ohm monolithic resistor specification to reduce electromagnetic noise that may affect electronic devices. (For all plug types)
3Highly Corrosion Resistant, Burnished Nickel Plating
The plug housing is plated with burnished nickel, the same as plugs used for racing. It is highly resistant to corrosion and rust even while touring in continually rainy weather and during motocross events. (Low-heat range types excluded)
4360° Laser Welding
The process used to mount the iridium tip is a highly reliable “All-around Laser Welding” process that is able to withstand all kinds of driving conditions. (For all plug types)
5Projected Center Electrode
In order to improve ignitability, the center electrode protrudes more than with conventional type plugs. This improves both acceleration response time and performance.(Only with: IU31, IUH24, IUH27, IX22, IX24, IX27, IUF22, IUF24, IWF22, IWF24, IWF27, IW24, IW27, IW29, IW31, and IW34)
60.4 mm Diameter Ultra-fine Iridium Center Electrode
Using a new iridium alloy with a very high melting point, the tip of the electrode can be made very fine. This enables the reduction of voltage necessary to cause the spark, and greatly improves ignitability. Moreover, the special iridium alloy used was developed by DENSO
7Taper-cut Ground Electrode
The tip of the ground electrode is cut to a fine taper to reduce the adverse effects of quenching, which greatly improves fuel ignitability. Also, because of the streamlined, taper-cut shape, the fuel-air mixture spreads more evenly in the gap, resulting in steady, reliable igniting of combustion.(excluding IUF27A, IUF31A, IU24A, IU27A, IU31A, IY24, IY27 & IY31)
8U-Groove Ground Electrode
The U-shaped groove on the ground electrode insures that the inside surface area is large enough to generate the flame kernel. This shape enables lower voltage needed to cause the spark and results in excellent ignitability without increasing the size of the spark gap. (excluding IUF27A, IUF31A, IU24A and IU31A)
9Insulator Projection
The projection of the insulator is optimally designed based on each plug's thermal value. This corresponds to requirements unique to thermal value, such as self-cleaning ability at lower thermal values, and heat resistance at higher thermal values. (For all plug types)


Improved Horse Power (1)

Get more power with an optimal fuel cycle.

IRIDIUM POWER has a low required voltage and a high ignitability, resulting in less misfiring and no spark, the outcomebeing a dramatic improvement in combustion. Engine output is thus increased. The findings of a bench test using a motocycle engine to show the improved combustion from
IRIDIUM POWER is shown on the below. Compared to normal plugs, a 0.5ps (1.4%) improvement is seen in output at 110 km/h.

Improved Horse Power (1)

Improved Acceleration

Increased response and acceleration performance.

IRIDIUM POWER best demonstrates its performance improvement during acceleration.
IRIDIUM POWER has a 0.4 mm diameter iridium center electrode and a specially shaped ground electrode. These features combine to achieve higher ignitability and require lower spark voltage than ever before. This enables high-response driving with fewer misfies than under higher required voltage spark conditions, and fewer misfies when ignitability is difficult. As a result, acceleration improves in comparison with normal plugs.

Improved Acceleration

Improved Horse Power (2)

The 0.4mm center electrode increases output under various driving conditions.

The power produced by the 0.4mm dia. iridium center electrode is IRIDIUM POWER unmatched by other plugs. The graph below compares the resulting power when IRIDIUM POWER is installed compared to other high performance plugs. Using a 0.4mm dia. fine center electode, there is more power compared to 0.8mm and 2.5 mm dia. plugs. This is what makes the difference in acceleration and in your lap time.

Improved Horse Power (2)

Improved Fuel Mileage

Even during idling ignition is assured, with less fuel consumption.

The good ignitability from the fine electode (0.4 mm) of IRIDIUM POWER draws out much more performance from the engine. Comparing a normal plug (W20FS-U) with an IRIDIUM POWER (IWF22) on a 2-cycle 50cc engine, fuel consumption improved from 41.74 km/L → 43.69 km/L, an improvement of about 5%.

Note: Mileage measured using a chassis dynamo; actual driving results under normal conditions may vary.

Improved Fuel Mileage