SOHC.co.uk Forums > CB750
Spark Plug
JamesH:
--- Quote from: K2-K6 on March 16, 2023, 07:46:33 AM ---
--- Quote from: JamesH on March 16, 2023, 01:16:31 AM ---The key point here is that higher performance engines require a ‘colder’ plug to help disperse the resultant heat from combustion faster. The ceramic insulators on ‘colder’ plugs are generally smaller, allowing faster heat dispersion.
In the Denso terminology, the bigger the number the colder the plug. So an X-22 is a ‘hotter’ plug compared with the X-24 which is ‘colder’ in Denso terminology.
--- End quote ---
I agree James but with the nature of interpretation I describe the colder plug as having larger insulation for more dispersion in surface area from plug tip to plug wall and then onward to the cylinder head casting.
(Attachment Link)
It is a bit semantics though as so many describe in opposite direction as I've found over the years, champions I always have to reference the numbers as it just doesn't stick in my mind like NGK :)
--- End quote ---
Fair point (late night post). What I probably should have referenced was the ‘gas pocket’ clearly shown in your pics above. In Denso speak ‘colder’ plugs generally have a larger gas pocket, and larger ceramic insulator / surface area, hence slower heat dispersion away from the plug (and vice versa).
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Johnwebley:
--- Quote from: Oddjob on March 15, 2023, 09:39:15 PM ---I was under the impression that colder plugs had higher number than hotter plugs. So an X24ES plug would be colder not hotter. As it happens it's recommended by NGK to go a step colder when using Ethanol so the X24ES would be better if that's the case.
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I have been using D8 in my 500,and 200,
the 500 runs well,
ordered 6 X24 to try,
Johnwebley:
--- Quote from: Johnwebley on March 16, 2023, 11:07:26 AM ---
--- Quote from: Oddjob on March 15, 2023, 09:39:15 PM ---I was under the impression that colder plugs had higher number than hotter plugs. So an X24ES plug would be colder not hotter. As it happens it's recommended by NGK to go a step colder when using Ethanol so the X24ES would be better if that's the case.
--- End quote ---
I have been using D8 in my 500,and 200,
the 500 runs well,
ordered 6 X24 to try,
--- End quote ---
Okay sitting outside in the welcome sunshine, listening to Simon Mayo album show, before going over to Johnny Walker,
Fitting the new Denso x24 plug
2 for the 200,at 25thou
4 for the 500,set at 32thou,
Started up,both running sweetly
These are the D8 ngk out of the 500,
A little dark on the outside, during to starting to warm it up,I find the plug come out easily if it's warm
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Oddjob:
32 thou John, that's a little wide, pretty sure they should be 25 thou or something like.
Johnwebley:
--- Quote from: Oddjob on March 19, 2023, 03:22:53 PM ---32 thou John, that's a little wide, pretty sure they should be 25 thou or something like.
--- End quote ---
With the Boyer giving a nice fat spark I make use of it
Gives what appears to be a good burn, look how clean the plugs are,
The engine seems to like it,
Very responsive
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