Suzuki Spark Plug NGK - DL 650 V-Strom 2004-2012

Part No: CR8E (1275)
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This is the Standard plug for the DL650's V-Strom

Technical information

Operating Temperature
The operating temperature of a spark plug varies between 450-870 °C.
Heat Range Explanation 
Typically the heat range for NGK Spark Plugs varies from 2-11.
This number indicates the thermal characteristics of a spark plug,
or how ‘hot’ or ‘cold’ a spark plug is. The term hot/cold is commonly used to
describe whether a spark plug heats up easily (hot) or whether it provides
resistance to heating up (cold).

Generally, low power engines such as lawn mowers don’t produce a large
amount of heat, hence use a low heat range (or hot) spark plug such as a
4 heat range. This means the spark plug will heat up easily and reach its
optimal operating temperature. High performance engines on the other
hand produce a large amount of heat, hence a high heat range (or cold)
spark plug such as a 10 heat range needs to be used to resist the heat
developed by the engine.

Several factors influence the heat range of a spark plug, although typically
the insulator nose design provides an indication of the heat range of a
spark plug.
When a spark plug absorbs heat produced from combustion, the heat is
transferred through the centre electrode and insulator nose to the metal
shell, which then transfers the heat into the engine casing and circulating
coolant.

A low heat range (or hot) spark plug typically has a long thin insulator
nose which will heat up easily however will not dissipate readily to the
metal shell (above left). Conversely, a high heat range (or cold) spark
plug has a short thick insulator nose which will dissipate heat much
easier (above right).

When the heat rating is too high:
The spark plug temperature remains too low and causes deposits to
build up on the firing end; the deposits offer an electrical leakage path
that gives rise to loss of sparks.
When the heat rating is too low:
The spark plug temperature rises too high and induces abnormal
combustion (pre-ignition): this leads to melting of the spark plug electrodes
as well as piston seizure and erosion.NGK Spark Plugs pioneered the use
of a copper cored electrode in 1958, which enables a spark plug to heat up
quickly and also dissipate heat quickly giving an ultra wide heat range. It is
essential to use a spark plug that fits a specific engine and its conditions of use.
As spark plugs are positioned in the head of an engine, their analysis can give
a good indication of how your engine is operating.

​

 

Spark Plug Analysis
Appearance of a used spark plug tells a lot about the operating conditions
of the engine and the plug. Thus the analysis of a plug plays an important
role in the maintenance of a car.

1 : Carbon Fouling

Carbon fouling is the most common spark plug related failure, but is not a spark plug fault.
Carbon deposits are conductive, and as they accumulate along the insulator nose they reduce
the insulation resistance of the spark plug. As electricity always takes the path of least resistance
a misfire may occur if a significant amount of carbon deposits accumulate. A spark will not form
as electricity can track along the conductive carbon deposits to the metal shell (as shown in red below)
rather than forming a spark across the electrode gap which has a very high resistance.

   

As mentioned the optimal operating temperature range for a spark plug is 450 – 870°C, 450°C
is the spark plug self cleaning temperature at which point carbon deposits will burn off. However,
if too cold a spark plug is used and this temperature is not achieved carbon fouling will occur.
This is the most common reason for carbon fouling.

Other causes for carbon fouling include:

Causes		Corrective actions
Air/fuel mixture (A/F) too rich	==>	It is necessary to service the carburetor, the auto choke system or the fuel injection system.
Incorrect adjustment of carburetor
Faulty auto choke system
Faulty fuel injection system
Faulty electrical system	==>	It is necessary to service the electric system.
Poor connection of high tension cables
Inadequate running conditions	==>	It is necessary to run at higher speeds (about 80 km/h) from time to time.
Prolonged idling
Continuous low speed driving
Too cold a spark plug	==>	Use a hotter spark plug (Example: BK R6E-11 --> BK R5E-11)
Air cleaner contaminated

As carbon builds up, the insulation resistance of the spark plug drops and the voltage generated
by the ignition coil is reduced. When the generated voltage becomes lower than the required
voltage of a spark plug (the voltage needed to cause sparks at the spark gap), sparking is
suppressed and mis-firing occurs.
 

2 : Terminal Nut Wear

Excessive vibration of the engine may lead to abnormal wear of the terminal nut. As a result,
the cover may come off the plug. For vehicles whose engines vibrate more than others,
such as watercraft and snowmobiles, solid post terminal plugs with excellent vibration
resistance and wear resistance are recommended.   
 

3 : Flash-Over - Spark leakage from terminal to metal shell      

Flash-Over When the spark gap has widened due to wear of the electrodes,
a higher voltage is required. The flash-over occurs when the required voltage
between the plug electrodes is higher than the voltage flying between the
terminal and metal shell.
The plug cable material hardens as time elapses, which in turn reduces the
tightness of the cover and insulator, lowering the preventive power for flash-over.

As a higher voltage is required for a turbo charged engine, flash-over is more
likely to occur. It is important to recognise that a plug cable is a consumable
part which needs to be replaced periodically. When there is no spark after washing
the car or the engine room, check whether water has entered the plug cover or not.

    

 

4 : Corona Stain

A removed spark plug sometimes has discolouration around the insulator surface which
looks like gases have leaked between the insulator and the shell. 

It is not a stain caused by gas leakage but by corona discharge (Carona Stain).

    

   

Mechanism of corona discharge

The high voltage applied to the spark gap is also applied to the area between the
centre electrode and the metal shell, causing an insulation breakdown of the air
at the gap (a) between the insulator and the metal shell. The phenomena is called
a corona discharge. The generated carona discharge develops toward the terminal nut.
This last process is the pale blue carona discharge that is observed at night.

5 : Metal shell - Rust, breakage at caulked portion

When water has entered the plug hole due to water resistance of the plug cover or,
in the case of a motorcycle, when water has accumulated due to the inadequate
draining through the plug hole, the metal shell may rust.
The rusting of the metal shell causes no deterioration of the function of the spark plug.
Note, however, that water inside the cover may prevent sparks from being generated.

If the plug is forced to remove when the returning torque is abnormally high due to some
causes such as plug thread seizure, the plug may break at the caulked portion of the metal shell.

When returning torque is high, the engine should be first warmed up. Then,
by spraying penetrating liquid around the plug thread and leaving it for a while,
the plug can sometimes be removed more easily.

 

6 : Firing End - Broken ceramics, melted electrodes, deposits

When the firing end of the plug has overheated, the ceramics may break
or the electrodes may melt. Under usual engine condition, the plug does
not overheat. Note, however, that it gets extremely hot in the case of
abnormal combustion (ex. high - speed knocking, pre - ignition).

When the A - F setting is lean due to a faulty fuel system, the combustion
temperature may rise, resulting in abnormal combustion. The engines
cooling system may be faulty. When the spark timing is too early, the
combustion temperature may rise, resulting in abnormal combustion.
When deposits (generating from combustion) are accumulated in the
combustion chamber, the combustion temperature may rise, resulting
in abnormal combustion.

When deposits have accumulated on the firing end of the plug,
deposits may overheat, causing abnormal combustion.
Especially in a two - cycle engine, oil gets burned and remains in
the combustion chamber as deposits, accumulating on the plug as
well. It is necessary to remove these deposits periodically.

In engines that consume larger amounts of oil, oil may enter the
combustion chamber. It is necessary to check the amount of deposits
during inspection of the plug. Burning of oil can also be detected by
visible white exhaust gas emitted from the tail pipe.

7 : Dry and wet fouling 

Wet fouling is fundamentally similar to carbon fouling. Although the root
cause may vary due to a number of reasons, in essence the insulation
resistance is reduced allowing a spark to track along the insulator nose
and earth to the metal shell rather than forming a spark across the electrode
gap as desired. Please see 1. Carbon Fouling

8 : Insulator - Breakage at the corrugation and caulked portion

When removing or installing the plug, the plug wrench may slip or be tilted and may hit the
corrugation of the plug against the inside, breaking the insulator.
Depending on the type of plug wrench, the plug may break at the caulked portion of the
metal shell. This may not be noticeable from the outside appearance.
Slipped wrench leaves a mark on the hexagonal portion of the metal shell. A plug wrench
with a definite hexagonal shape should be used. A rounded or loose wrench should be
either avoided or used with special care.

9 : Under or over tightenin

When the plug has not been tightened enough, the combustion gas leaks out
the thread portion. This reduces the radiation of the plug, causing the metal
shell to be heated, resulting in discolouration of the metal shell plating.
If the metal shell continues to overheat the plug temperature may rise and
abnormal combustion may result. When the plug has been tightened too
much the thread neck portion of the metal shell will be lengthened.
When the threaded neck portion is lengthened, the insulator and metal will
not seal tight enough, causing the combustion gas to leak. When the gas
continues to leak, the plug will be overheated and abnormal combustion may result.
The plug should be tightened to the following recommended torques and turning angles.
When the plug is tightened too much the metal shell thread neck may be broken at
around the first to second thread. The plugs with smaller diameter portions,
the D (12 mm) or C (10 mm) types thread neck portion is not very strong.
Observe the recommended torque and turning angle and tighten with special care. 

10 : Plug socket troubles

Damage to spark plugs during installation can easily occur and will often result
in an intermittent misfire or no spark at all. Care must be taken during
installation that the spark plug socket is not slanted and does not slip causing
insulator breakage (See Figure 1). Internal damage can still occur without the
insulator actually breaking. Any horizontal force can either bend the terminal
post internally or result in internal cracking of the insulator.
To avoid plug damage the following qualities are required in a wrench
1. That it fits the spark plug "hex" properly.
2. The inner space must be large enough to avoid contact with the insulator.
3. The spark plug socket must completely cover the "hex" portion of the metal shell.
4. A hexagonal socket is preferable as it is less likely to slip than a twelve point star type.

11 : Examples of problems caused by excessively over long periods of use 

Deposits accumulated on the firing end may induce abnormal combustion (pre-ignition)
causing problems that include melting of the electrodes.

	Good
	Worn Electrodes If the edges of electrodes are worn and rounded, sparks will not easily occur, which leads to engine starting problems and mis-firing during running: maximum power cannot be obtained from the engine.
	Fouled Power leaks through the carbon accumulated on the firing end, causing mis-firing as well as hindering engine starting.
	Deposits The deposits accumulated on the spark plug overheat and cause abnormal combustion (pre-ignition) that may lead to melting of the electrodes of the spark plug.

Why is the firing end appearance of a spark plug important?

Because the Firing end appearance reflects the suitability of the spark plug as well
as  the condition of the engine. There are three basic criteria: good, fouled,
and overheated. The firing end appearance also depends on the spark plug tip temperature.

The boarder-line between the fouling and optimum operating regions
(450 degrees Celsius) is called the spark plug self cleaning temperature.
It is at this temperature that the deposits accumulated are burnt off.

What is spark plug fouling?
It is a phenomenon by which carbon attached to the firing end causes electrical
leakage that leads to mis-firing.
As the high voltage generated by the ignition coil leaks away through the carbon,
mis-firing may occur and cause running and starting difficulties.

What is spark plug overheating?

Prolonged overheating may induce abnormal combustion (pre-ignition), resulting
in melting of the spark plug electrodes. 
Overheated spark plugs have a white insulator surface at the firing end speckled
deposits. Electrode melting represents excessive overheating. When the spark plug
temperature exceeds 870°C, the firing end serves as a heat source before sparking
and induces abnormal combustion (pre-ignition), possibly damaging the piston.

 

Causes of overheating and corrective actions

Causes		Corrective actions
Ignition timing too far advanced	==>	Adjustment of ignition timing is required.
Air/fuel mixture(A/F) too lean	==>	Adjustment of air fuel ratio (A/f) is required.
Insufficient cooling water and lubricants	==>	Top up cooling water and lubricants
Applied turbo boost pressure too high in the  case of a turbo engine	==>	Adjustment of turbo boost pressure control is required.
Insufficient tightening of spark plug	==>	Tighten to specified torque
Use of too hot a spark plug	==>	Use colder spark plug (Example: BK R5E-11 --> BK R6E-11)

 

What is lead fouling?

Lead deposits accumulated on the spark plug firing end help electricity to leak
away and result in mis-firing. When the lead contained in gasoline as an octane
enhancer, adheres as the firing end of the spark plug, the high voltage generated
by the ignition leaks through the lead deposits and causes mis-firing during
acceleration. This problem often takes 2,000 ~ 3,000 km (1,200 ~ 1,800 miles)
to become apparent.

 

Insulation resistance of a spark plug vs. vehicle speed.
Lead fouling does not appear during starting or low speed running.
On the other hand, mis-firing occurs when accelerating from the
middle speed range since the insulation resistance of the spark
plug drops quickly.
 







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Better selection of spark plugs.
Use hotter type (Example: CR7E - CR8E)