[frank]

one of my spark plugs fouled and i was only running on three cylinders. being down here in the caribbean, i could only get a hold of these spark plugs: ngk iridium ix cr8eix 4218

the bike is running fine and the originals were iriduim ngk 9's. any idea if it's ok to run my cbr 954 bike on these? my mechanic down here told me that it should be fine and that the new spark plugs, being 8 instead of a 9, just means it will burn a little hotter. i need some advice.

ps. i have 60,000 km on my bike.
thanks, frank

 

[bladeracer]

my mechanic down here told me that it should be fine and that the new spark plugs, being 8 instead of a 9, just means it will burn a little hotter. i need some advice.

It probably will be fine but pull them in a few hundred kms and see how they look. If they're covered in carbon you'll need "hotter" plugs to burn it away. If they're blistered you'll need cooler plugs to prevent pre-ignition.
The heat range doesn't make them run hotter or colder.
The range indicates how hot the engine needs to run for them to work best. If your combustion chamber temps are lower then you need a "hotter" plug.
The combustion chambers on your stock engine work best (according to the people that manufactured it) with a plug of "9" heat range under normal conditions.
An "8" plug is designed to run in a hotter combustion chamber so it may not get hot enough to burn the carbon deposits left by combustion. In summer you may get away with a colder plug as the combustion is slightly cooler anyway. In winter it'll be more likely to foul. Or is the other way around - it's really confusing

 

[bladeracer]

Try this.

NGK Spark Plugs USA

That explains it much better - and correctly
Best to disregard what I wrote and follow NGK's information.

 

[frank]

Thanks Bladeracer. i'll use these plugs just long enough until the originals arrive from the USA in about ten days.

And as always, thanks for getting back so quickly with an answer. frank