Spark plug question

[TravisBickle]

Hi guys

Just a quickie this time. Ordered a set of spark plugs from Fowlers by selecting my bike from the list, CR8E was identified as the correct spark plug for my bike.

Went to remove the old spark plugs and although they look identical to the new ones (same total length, seat position, thread etc) the code on the old ones is CR9E.

I fitted them anyway and the misfire/splutter that was there before is still present (so I'm now thinking carbs), other than that everything else seems to be running the same as it was before.

Is this something I should be concerned about? Could it be I was sent the wrong spark plugs for my bike? Or maybe because they're nearly identical despite the difference in code the previous owner just used CR9E instead of CR8E because that's all they could get hold of at the time and didn't actually make a difference to the running of the bike?

Obviously each character in the code means something, probably a reference to the specs of that particular spark plug. Can someone explain what all the numbers and letters mean please?

Many thanks!

[Howling TerrorOutOfOffice]

Hi,

Tell us the make model and year of your bike and I bet someone on here will tell you.
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[Nobby the Bastard]

The number 8 plug is a slightly cooler one than a number 9 plug. The cooler the plug, the smaller the bowl round the electrode is.

The bigger the bowl, the bigger the the initial detonation is becuase it can hold more mixture. If it is difficult to start and tends to run cool, go for a hotter plug, conversely a hotter plug can cause overheating and knocking.
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[TravisBickle]

[Nobby the Bastard]

Possibly.

It's also just as possible that they'd heard some bollocks about hotter plugs increasing power.

Try the 8s and see what happens. If it runs like a bag of nails, try putting the 9s back in.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Feathers McGraw]

[Nobby the Bastard]

[TravisBickle]

[Nobby the Bastard]

[Polarbear]

I would very much doubt the difference between an 8 or 9 rated plug will be even noticeable on a larger cc lower tuned 4 stroke. However my standard statement in all cases like this is go with the manufacturer recommendation as long as your engine is standard.

When I had 2 strokes it could be critical especially after so home made tuning. It could be the difference between a solid piston or one with a hole in it

You haven't got that worry
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[TravisBickle]

[Polarbear]

[Fizzer Thou]

The correct NGK spark plug for the FZS600 is the CR8E.

The higher the heat range number specification,the colder or harder conditions the plug will run in.

As a good example,my old Honda CB550K3 (c.1978) usually ran a D7 type spark plug.As I also rode a CB750F2 and the plugs were a D8,I tried the cooler plug in the CB550.When I say that I tried them,they did not work at all.As soon as I reverted back to the D7 type,the CB550 ran perfectly.
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[TravisBickle]