Spark Plug

[Erny]

Which Denso plugs? X-24ES?

24's are fine on a 750 sohc 

What is DENSO alternative for 500/550?

DENSO is not copied as NGK?

[Trigger]

Which Denso plugs? X-24ES?

24's are fine on a 750 sohc 

What is DENSO alternative for 500/550?

DENSO is not copied as NGK?

X-24ES for 400 four, X-22ES for 500 four, 550's and  X-24 for 750K's 
Never come across a copy Denso to date .

[Oddjob]

Which Denso plugs? X-24ES?

I bought a box of 10 Denso plugs from here Martin, reasonably priced as well, in fact cheap.

https://www.gsparkplug.com/1x-denso-standard-spark-plugs-x24es-u-x24esu-067800-1700-0678004130-4099.html

[Sesman]

£25 for 10No  inc post👍

[Seabeowner]

Which Denso plugs? X-24ES?

24's are fine on a 750 sohc 

What is DENSO alternative for 500/550?

DENSO is not copied as NGK?

My workshop manual and owners manual quotes X22ES for 500s. Denso no 4090.

[Oddjob]

Quite right it should be X22ES, that would have been what I bought, they've been in a box in the loft ever since.

TBH I've never used Denso except for a time in the 70s, I've always used NGK but for the price of the Denso plugs now I'll take a chance on them, plus no copies unlike the NGK plugs

[Spitfire]

I've been using Denso X-24ES-U plugs in my 750F1 since I got the bike on the road after rebuild around 2008i sh and they work a lot better than the NGK's now that you can't get the proper ones (D8ES-L).

Cheers

Dennis

[Trigger]

Which Denso plugs? X-24ES?

24's are fine on a 750 sohc 

What is DENSO alternative for 500/550?

DENSO is not copied as NGK?

My workshop manual and owners manual quotes X22ES for 500s. Denso no 4090.

That is correct    but, you can use either . The X-24 are a hotter running plug than the X-22 and i have found if you are only using the bike in fine spring and summer weather the X-24 are a better plug, which have been superseded to the X-24 ES-U . Seeing most members that do ride a SOHC, don't ride in cold conditions 

[Trigger]

Forgot to mention before. It is not just spark plugs that have superseded over the years, it is also fuel. The X-24ES-U is more suitable for E5 and E10 petrol   

[Sesman]

Please, do tell…..

[Oddjob]

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.

[Trigger]

I was talking about DENSO plugs, NOT NGK  I think you need to go back to spark plug school as, they are a lot more complicated these days 
All spark plug manufactures have there own heat range, and that is heat transfer from the engine. The plug can differ from standard copper up to Iridium which all have there own heat dispersal 

[JamesH]

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.

[Oddjob]

And as far as I can determine that’s exactly what I said, higher number colder. So an X24es would be a colder plug than the X22es not hotter.

Maybe I was there that day.

[K2-K6]

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.

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.

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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