Topic: do colder plugs 'feel' diferent?

[johnyvilla]

My appropriately jetted 836 overheated on a spirited 85 degree day this weekend. I have ordered a cooler but until then, I plan to increase my mains and use colder plugs to be on the safe side. I am taking the bike out of state this weekend and I will have many  hours to interpret every nuance of my engines behavior, all the while looking for signs of overheating. I've never run anything but the standard heat range of plug.  What can I expect? Slow starting? Top power decrease? Or are the changes from colder plugs difficult to detect?
Thanks

[Rampage1967]

My appropriately jetted 836 overheated on a spirited 85 degree day this weekend. I have ordered a cooler but until then, I plan to increase my mains and use colder plugs to be on the safe side. I am taking the bike out of state this weekend and I will have many  hours to interpret every nuance of my engines behavior, all the while looking for signs of overheating. I've never run anything but the standard heat range of plug.  What can I expect? Slow starting? Top power decrease? Or are the changes from colder plugs difficult to detect?
Thanks

Colder plugs will not reduce the operating temperature of your engine.
The heat range of the plug only deals with the operating temperature of the spark plugs firing tip.
Now, if you install plugs so cold they foul out you engine will run colder since no combustion will take place 
If your plugs are so hot they cause preignition, your engine will overheat & go into detonation. This will also result in a nicely holed & beuatifully melted set of pistons if it goes on long enough. 

So, to answer you question. Unless they foul out, no you should not notice any difference from colder plugs. If the engine is running typical dark colored plugs of a CB750 I would not go colder myself.

[Don R]

  How hot was it and how could you tell?
  Am I correct the mains will affect mixture mostly above 3500-4000 rpm? the low speed jets control idle and off idle and the needles and needle jets control from off idle to above mid range? So a needle position change would only affect mid range?
  We tune our drag cars fuel jets by temp increase during a 1/4 mile run.

[johnyvilla]

Thanks for that explanation. Plugs are caramel colored with standard plugs.

I know it overheated when I tried to start it up after a hot run and it seized. I've since jetted richer for safe measure, though Power is down in this configuration.

[nokrome]

i was having heat problems on my 850, while i was experimenting with different jet configurations one of the things i tried was to run a set of d9ea's
   they foulled out almost immediately
    if your plugs are caramel colored that sounds about right
       when you get your cooler installed that should help a bunch (which cooler did you get ?)

[johnyvilla]

D8ea's but I might not even install them. I jetted richer, and although the bikes not quite as quick, it is running cooler.

[Nikkisixx]

When you have a minute and need a good read, go here:

http://www.ngksparkplugs.com/tech_support/spark_plugs/p2.asp?mode=nml

[eurban]

I switched to D9s in my 836 project for a few reasons.  I was noticing some light pinging under load on hot days (with high octane gas) so I thought I might see if any improvement was made with a plug with a lower operating temp (less likely to pre ignite).  Pinging has been reduced . . .The D8s plugs were also showing very little indication of coloration, in spite of all other indications being that the mixture was good.  The D9s show healthier coloring.  Overall, upping the compression ratio to 10.25-1 (typical street big bore) most certainly increases the heat in the combustion chamber and on theory alone, a colder plug makes sense.  I have had zero issues with fouling and my bike started well this winter in 20F temps.  I run a dyna III ignition with 3 ohm coils and have relayed the the coil/ignition's power supply to provide full available voltage(I have also "detailed" the entire electrical system).   

[fire113]

I switched to D9s in my 836 project for a few reasons.  I was noticing some light pinging under load on hot days (with high octane gas) so I thought I might see if any improvement was made with a plug with a lower operating temp (less likely to pre ignite).  Pinging has been reduced . . . 

...under load I have a light pinging too but only sometimes 
I think I will try the D9s.

THX...fire113