Spark Plug question for 1100 vs 1200

[FJTillDeath]

Hi all been reading through the pwners manual and at the quick referrence section where it mentioned the spark plug data for a 1200 to be "NGK DP8EA-9" Now I know from memory a while back when I pulled the plugs on my 1100 they were all NGK DP8EA-8's.

I cant recall if 8s have a higher or a lower heat rating, but when I had pulled the plugs they had all seemed fairly fine.

My question is should I go with what the manual says as a "9" or run the "8"s I have? I dont have the side scoops for my bike so the engine cams do run a little hotter than they should. Also, is the slight ping I have maybe related to running the 8s instead of 9s? or is that just from the engine running hotter than it should.

Jesse

[andyb]

Higher numbers are colder, for NGK.

Most people worry far too much about it.  If they came out without looking bad, you're probably okay.  If you want to experiment, go ahead, they're reasonably cheap, and if you don't see a difference, then you'll have a spare set.  A street engine that rides the ragged limit and absolutely hates a certain plug is tuned way, way too far to an extreme and will probably get damaged on a bit of bad gas or such!

[rktmanfj]

http://www.ngksparkplugs.com/techinfo/spark_plugs/partnumberkey.pdf

[andyb]

That chart doesn't apply to racing plugs by NGK, incidentally.  Those start with an "R" and cost a mint, so it's not a mistake you're likely to make in the first place anyhow.

[FJTillDeath]

Okay well cool, I am glad to know I have no need to worry. For some reason the 9s are much easier to get than the 8s where I am so on my next change I'll be running the 'recommended' spark plugs.

[RichBaker]

Heat range is the # between the DP#EA, the -# denotes the gap they're designed for......

[andyb]

Damnit rich, don't take my fun away.

[FJTillDeath]

Took a look at what spark plugs I actually have just to confirm and by what Rich says I am running 1 heat level too low and that I also have a plug thats not actually meant for the gap I have.

This is worrying to me, but plugs still look normal?(they look the same as they did a 1000km ago So I am not really worried anymore)

Will continue to use them for the rest of the usefull life and then get what the manual says I should have

(one problem at a time after all)

[Brook]

....... I also. have been using NGKDP8EA9 plugs. ...But, when I sent the motor out for a complete rebuild, it came back with Autolite AR4152.
   anyone know how the Autolite's compare with the NGK's?

[FJTillDeath]

....... I also. have been using NGKDP8EA9 plugs. ...But, when I sent the motor out for a complete rebuild, it came back with Autolite AR4152.
   anyone know how the Autolite's compare with the NGK's?

Neither of them are recommended but as Andy said

Most people worry far too much about it.

Ask your dealer why they put them in in the first place, depending on his answer you may or may not need to replace them

[andyb]

....... I also. have been using NGKDP8EA9 plugs. ...But, when I sent the motor out for a complete rebuild, it came back with Autolite AR4152.
   anyone know how the Autolite's compare with the NGK's?

Supposedly that's a racing plug, so finding interchange info isn't easy (it's not a direct swap to a 'normal' plug).

Only differences physically seem to be that it uses a different socket than the NGK and that it's a resistor type.  Let us know how they work for you!

[Brook]

...... Ok andyb, I will do that. .. I have another question, speaking of hot and cold plugs,   when you have the [relay] set-up for the coils, should that make a difference in the type of plugs you use? or the gap?

[srutherford]

NGK for me always just my .02  im a big oem slug i like em the way its supposed to be