Spark Plugs, Heat Make a Differnece?

[Honda 250r 001]

Which plus is hottest and which is coldest? b7es, b8es, and b9es? What difference does it make to run a "hotter" or "colder" plug? Would running a colder plug make it run cooler? but with less performance?

Thanks

[BuDDy L]

b7 is the hotter plug, use the 8es, thats what i run in my 89 265r, it is also the honda reccommended plug to use by my honda store

Originally posted by Honda 250r 001
Which plus is hottest and which is coldest? b7es, b8es, and b9es? What difference does it make to run a "hotter" or "colder" plug? Would running a colder plug make it run cooler? but with less performance?

Thanks

[Honda 250r 001]

i think im going to try a b9es and see if it runs any cooler and then a b7es and see if it runs hotter. or the color changes on the plug.

Whats the purpose of using differnt heat ranges?

[BuDDy L]

Originally posted by Honda 250r 001
i think im going to try a b9es and see if it runs any cooler and then a b7es and see if it runs hotter. or the color changes on the plug.

Whats the purpose of using differnt heat ranges?

Spark Plugs either ignite the fuel mixture,,,or they dont.

If one plug Lights the charge,,,no other plug is gonna Add any extra benefit to that Specific Function.

It's as simple as that.

Yet,,,there's a BUNCH of technical characteristics spark plugs have which ARE Important to an engine's operation.

HEAT RANGE,,,,and "Hotter/Colder" is very widely misunderstood.

The Plug does NOT make Heat,,,
and Heat Number does NOT refer to anything the PLUG produces.

A B4 or B5(extremely Hot) fire exactly the same as B10 or B11 (Extremely Cold).

What it Refers to is the Plug's Function as a RADIATOR.

It's a comparative Ranking of the Plugs ability to REMOVE Heat away from it's TIP,,,and into the engine>then out into the air.

A Plug's Tip has an Optimum TEMP range to function properly.

If the TIP is Too Cold,,,it will foul with caked -on deposits.
It can also extend warm-up cycle time.
Example:Start an engine on a very Cold Plug,,,then Rev It,,,it will be very easy to FOUL the plug.

Because the Cold plug takes a "long time" to reach the PLUG'S self-cleaning temp

They also are more Prone to Fouling when shutting the throttle after a full throttle burst.
The Plug's Temp drops rapidly,,,and it gets coated with deposits "instantly" from the Temp Differential in the Combustion chamber.

.....................
Hot Plugs are SLOW to transfer their tip heat,,as well as Reaching Higher absolute temps

They reach optimum TIP temp quicker on cold start,,,and maintain that "self-cleaning temp" Longer during Decelleration.

If they are TOO Hot,,,and cool Too Slowly,,,,their Tip can reach an Auto-Ignition point.
Hot enough to ignite the fuel BEFORE actual Plug Firing occurs.

If the Tip becomes excessively Hot,,,that can create a different type of Fouling.
It can Glaze various chemicals in the oil/fuel into a NON-conductive "insulation" on the Plug Tip,,,
OR into a CONDUCTIVE coating on the Tip,,which shorts out the plug

................................
So when you are selecting Heat Range,,,
all you are doing is "Tuning the Tip Temperature" of the PLUG in order to keep it within a range which;
A) Hot enough to ensure self-cleaning
B)Cold enough to avoid Auto-Ignition

Nothing More,Nothing less.

Hi-Perf engines typically use comparatively Colder Plugs because the engines often produce Sharp,Sudden Spikes in Combustion Chamber Temps at their Power Peak.

"Racey Motors" run in the Wisest range of Chamber temps.

Cold Plugs are a Necessary Evil in order to accomodate the surge in Temps at the engine's power peak.

At Lower-Than PEAK POWER,,,the plugs are "too cold" and often prone to fouling rather easily..

..................................
Your "R" is originally fitted with 8's anyway

If you're not having probs with Fouling or Plug Life,,,,You'll not see any benefits from a Heat Range change.

..................................
One exception of sorts is NGK's Iridium Plugs.

Their technology is such that under marginal ignition conditions,,,they can show an improvement.

They have a very wide heat range,,,making engine less sensitive to Ignition Demands under various operating conditions.

MOST engines Do Not fire 100% of the time,,,they DO skip a beat occasionally.
It's only a handful per 1000 strokes.

The Iridiums can eliminate or minimize that occurence.
Sometimes it's Noticeable,,,sometimes NOT.
It may be an improvement in,,
-cold start
-idle
-low speed operation
-throttle transition,,when accelerating
Who knows when/where???? Just No Tellin'.

But they are proven to reliably ignite more consistently,and under a wider range of conditions than standard plugs.

If your "R" is running good,,,,
as far as ignition goes Not even a Flamethrower will make any worthwhile improvement.


**Symptoms of TOO HOT a Plug are an odd "poof" sound from the exhaust which becomes extreme as rpms increase.

Thats caused by IGNITION occurring Prematurely while Exhaust Port is still Open.
So it's Literally Combustion Occuring inside the Exhaust Pipe,,,rather than in the Combustion chamber.

You'll Know it immediately,,,it's NOT a subtle thing.

Engines which "get Damaged" from Too HOT a Plug are NOT being Damaged by the Plug's Heat Range.
That's a MYTH & Misunderstanding.

If the Plug becomes TOO HOT,,,
I Gaurantee Ya it WILL Pre-Ignite Fuel before it melts aluminum.

Other Conditions are the Root Cause of the destruction,,,Poor 'ol Spark Plugs are just a Patsy which gets blamed for it.

An engine with a Too-Hot Plug can be triggered Very Quickly and Suddenly in Pre-Igntion.
But the Excess Temp Spike in the Combustion Temps is NOT the PLUG's Fault.

The Plug is simply overwhelmed by it,,,
making the PLUG the First Victim in the chain of Overheating events.

Spark Plugs are NOT Temp Sensor Safety Fuses.
Yet they DO act to give early warning of overheating.

If they FAIL at being used as a Safety Device,,,which they are Not designed or intended to do,,,
It's silly to Blame the "Hot Plug"



Good Luck,,hope that helps

[speedfreek]

You need to do a plug chop to see what plug you need. If you know your compression, I can tell you what plug you may need. But the only safe way is to read it after a wide open run.