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Spark plug heat value table comparison

Spark plugs for scooters Vespa, Lambretta & Co.

My personal spark plug universe is quite small and simple:

  • Original engines: BOSCH W5CC
  • Easy tuning: BOSCH W4CC
  • Ambitious tuning: BOSCH W3CC
  • and sometimes also: BOSCH W2CC

It has always been like that for me and unfortunately it can't stay that way, because my universe has been crumbling for a long time! BOSCH spark plugs have not been around for a long time. Exception: We were able to get a large stock of BOSCH W3CC to back up. But no reason that the world should collapse for me, because of course we have great alternatives. But they are called different and a lower value is warm instead of cold ... Reason enough to take a look at the topic of spark plugs.

With us in Scooter Center Shop you get spark of the leading manufacturers.

 

spark

Spark plug thread

Spark plugs are screwed into the spark plug thread of the cylinder head. are available in different diameters and lengths. The usual threads are M10, M12 and M14. Classic Vespa and Lambretta vehicles have an M14 thread.
Modern engines, four-stroke and newer two-stroke engines with injection use the smaller plugs with M10 or M12.

The common thread lengths are 19mm (long thread) and 12,7mm (short thread). You should pay attention to the correct length of the spark plug and follow the manufacturer's instructions. A spark plug that is too long can damage the piston because it protrudes too far into the combustion chamber; a spark plug that is too short will certainly have a loss of power if the engine starts at all. Unclean combustion would quickly build up residues in the combustion chamber, which could damage the engine.

Long thread short thread spark plug correct length

 

Heat value

The heat value is decisive for the thermal fatigue strength of the spark plug and its self-cleaning effect. A distinction is therefore made between so-called cold and hot spark plugs.
A cold candle is for engines that develop a very high combustion chamber temperature, usually these are engines that have a lot of power measured by their cubic capacity. A hot candle, on the other hand, is used in lightly loaded series engines. This type of candle quickly reaches a high temperature, which means that the soot that accumulates on the candle burns away well.
The temperature resistance is achieved through differently designed insulators. A cold candle can give off a lot of temperature through the cylinder head, with a cold candle this is exactly what is prevented. The calorific value has nothing to do with the strength or performance of a spark plug. A cold candle in a cold (weak) engine becomes oily or sooty and can break without damaging the engine itself. A hot spark plug in a racing engine burns up and damages it, usually severely.
The heat value of a spark plug is not standardized. Each manufacturer has its own code here.

  • NGK from cold to hot = 10-9-8-7-6
  • Bosch from cold to hot = 2-3-4-5-6
  • DENSO from cold to hot = 37-34-31-27-24-22-20-16-14

Comparison of spark plug heat value

Noble noble, the electrode material

Copper, platinum, silver or even iridium are used here.
The most common is copper, followed by silver and platinum. Due to the high prices for the precious metals, the spark plugs are correspondingly more expensive than their copper counterparts.
Ultimately, the material is only of interest for wear and tear, only the extremely thin iridium electrodes (Ø = 0,6mm) have a higher ignition voltage, and the spread of the flame front in the combustion chamber is improved.

 

Caution is the mother of the ceramic candle!

The spark plug's insulator head is made of ceramic. It goes without saying that brute force shouldn't be used here. Spark plugs should be handled with care and, better still, not be dropped, and they should also be protected from moisture. Use one spark plug wrench with rubber insert.

 

Spark plug terms values ​​data

What is the tightening torque of a spark plug?

Is it too low selected, there is a risk of compression loss and overheating. A break in the insulator or center electrode as a result of vibrations is also conceivable.

Will that be Selected torque too high, the spark plug may tear off. The housing can also stretch or twist. The heat dissipation zones are disturbed, there is a risk of overheating and melting of the electrodes or even damage to the engine.

Manufacturers recommend for that professional assembly a spark plug torque wrench. Since we know that hardly anyone does that and that it doesn't work at all with the Lambretta, for example, you could follow the following rule of thumb:
Hand-tight = screw in by hand and then tighten a quarter to half turn with the candle wrench.

Our new bgm spark plug wrench: protects the spark plug and has a magnet so that you don't burn your fingers when removing the plug.

TIPP:
You can install and remove spark plugs with a fine one wire brush reinigen.

 

Spark plug picture

Using one Candle image you can also draw conclusions about correct combustion of your engine.

PERFECT: If the candle is "fawn" your engine burns perfectly.
SKINNY: If the candle is too bright - white, it will be too hot, the carburettor may be too lean or the ignition set incorrectly.
FAT: If you have a black, sooty spark plug, the engine is running too rich.

Spark plug candle picture brown white black lean fat?

spark plug

With a spark plug connector, you should pay attention to whether it is used with or without a spark plug nipple / SAE nut. A spark plug connector is also a part that is exposed to heat and vibrations and should be checked regularly and replaced if necessary.

A good spark plug only costs a few euros, which is a pleasure to invest.
TIP: I always have a second plug and ignition cable in my tool.

 

 

 

Bosch W3 CC - production discontinued

Bosch has the production of the popular spark plug W3CC set.

We got the last stock in order to be able to supply you as long as possible.

Buy Bosch W3 CC here

Sad alternatives

Now you might mean: “So what? I'm assuming an alternative identical spark plug like  NGK B8ES or Denso W24 ESU or a Champion N3C! "
You're not entirely wrong about that, these are the spark plugs with the same heat value! Still we are sentimental now, we grew up with “W3CC”. This spark plug went over our counter a thousand times over and we screwed it into a large number of cylinder heads.

We'll definitely get involved couple aside. You also?

Bosch W3 CC spark plug
Thread type: M14x1,25
Spark plug thread length: 19 mm
Spark plug thread: long
Key-width: 21 mm
Material electrode: Nickel
Electrode type: Standard
Spark plug with cap (thread protection): Ja
The cap (thread protection) can be screwed: ja
Heat value NGK: B8ES
Denso heat value: W24ESU
Heat value champion: N3C

Bosch spark plug

The spark plug explained

Thread diameter of the spark plug

The usual threads are M10, M12 and M14. Classic vehicles usually have an M14 thread. 4-stroke and modern 2-stroke with injection use the smaller plugs with M10 or M12.

Spark plug thread length

The common thread lengths are 19mm (long thread) and 12,7mm (short thread).

Heat value of the spark plug

The heat value is decisive for the thermal fatigue strength of the spark plug and its self-cleaning effect. A distinction is therefore made between so-called cold and hot spark plugs.
A cold candle is for engines that develop a very high combustion chamber temperature, usually these are engines that have a lot of power measured by their cubic capacity. A hot candle, on the other hand, is used in lightly loaded series engines. This type of candle quickly reaches a high temperature, which means that the soot that accumulates on the candle burns away well.
The temperature resistance is achieved through differently designed insulators. A cold candle can give off a lot of temperature through the cylinder head, with a cold candle this is exactly what is prevented. The calorific value has nothing to do with the strength or performance of a spark plug. A cold candle in a cold (weak) engine becomes oily or sooty and can break without damaging the engine itself. A hot spark plug in a racing engine burns up and damages it, usually severely.
The heat value of a spark plug is not standardized. Each manufacturer has its own code here.

  • NGK from cold to hot = 10-9-8-7-6
  • Bosch from cold to hot = 2-3-4-5-6
  • DENSO from cold to hot = 37-34-31-27-24-22-20-16-14

Electrode material

Copper, platinum, silver or even iridium are used here.
The most common is copper, followed by silver and platinum. Due to the high prices for the precious metals, the spark plugs are correspondingly more expensive than their copper counterparts.
Ultimately, the material is only of interest for wear and tear, only the extremely thin iridium electrodes (Ø = 0,6mm) have a higher ignition voltage, and the spread of the flame front in the combustion chamber is improved.

Buy Bosch W3 CC here