I have a 98 Banshee that has been ported/polished, bored twice over, Wiseco pistons, CPI Drag Pipes, Mikuni Flat-Slide carbs, etc. I run Sunoco Purple Race Gas and Klotz synthetic oil.

The person who built the engine recommends I use an NGK B9ES plug. My other Banshee is stock and the manual calls for a NGK B8ES plug.

The B8ES plug is hotter since NGK lists their heat range opposite from most plug companies. Why would anyone recommend a colder plug with my engine mods?

Should I use the hotter B8ES or the colder B9ES in my modded Banshee?

 

This is from the trinty web site , you might be able to tell witch is better from reading your plugs....

http://www.trinityracing.com/techtips/index.html


What is the proper jetting for my bike?

These specs are guidelines only (Sea level) and must be checked for your altitude and temp. Click Here For Specs.






How do I read my spark plug?
TO READ PLUGS PROPERLY YOU WILL NEED A 10x ILLUMINATED MAGNIFYING GLASS

1,2,3. This is how it's done!


1. You set your heat range from the ground strap. (this is the piece closest to the piston)

2. You do all the plug readings for jetting from the base ring (thebase ring is what the ground strap is welded to at the end of the threads)

3. You determine detonation and timing issues from the porcelain.
(The porcelain shows preignition/detonation, it will not accurately determine jetting / air/fuel ratios)

DO NOT BASE JETTING DECISIONS ON THE PORCELAIN COLOR.

1. How to determining plug heat range:

The ground strap is your window to getting this right. If the "color" of the ground strap "changes" too-close to the ground-strap's end, (the end opposite of the base ring), then the heat-range is "too-cold", (heat transfer is to quick to the base ring)
If the "color" of the strap changes near where it is welded to the base-ring, then it means that the plug heat-range is "too-hot", (heat transfer to the base ring is to slow causing the deposits to be burned off the strap completely) The strap at this point could start working like a "glow-plug", probably resulting in pre-ignition/and/or detonation. The properly set heat-range is when the "color" is at the half-way point on the strap.

2. Reading the base ring to determine jetting:

The base ring "color" is very close to the color of the piston crown and is used to determine the jetting. Your looking for the soot color to be a nice light to medium brown, (color is always hard to describe) if the color doesn1t go all the way around the base ring (at least one full thread turn on the plug) or the color is whitish it is way too lean. If the color goes all the way around, but there is a spotting of heavy dry soot on the top of the color, you are too rich. ( TWO STROKE JETTING WILL BE A LITTLE WETTER LOOKING AND DARKER THEN A FOUR STROKE )

3. Read the porcelain to determine detonation / preignition:

The first signs of detonation / preignition will be seen on the porcelain down in the plug, It shows up as tiny black or shinny specks of aluminum. Also Look very close around the center electrode where the porcelain intersects, this will appear to be melting between the insulator and the electrode.

Detonation is caused by the air/fuel mixture exploding rather then burning. This gives off a sound, (a knock) this sound is the result of a shock wave, this wave disrupts the boundary layer of cooler gases that cover the internal parts of the combustion chamber. This causes a very rapid rise in pressure and temperature. The results are holes in the top or sides of the pistons, blown head gaskets, broken rods, (all bad stuff) This can also shock the rings from there seal causing oil to form as little spots on the porcelain.

 

Dang, that's pretty complicated!

How about the rest of you on Banshees with serious engine mods. Which plugs do you run?

 

The engine bulider probably recommended the b9es because it is colder.
The heat range on a plug tells you how well it disipates heat. a colder
plug disipates heat better than a hotter plug. When you add a lot of mods
you generally increase the amount of heat that the plug has to disipate.
So you need a plug that will move more heat, a colder plug. I'd go with the
colder plug(b9es). If it fouls often you might change to back to a b8es. If
You do, you need to make sure it is not spark knocking any at all with the
hotter plug. If it does go with higher octane fuel of go back to the b9es.

 

I run alcohol and I was told that the 9's are what to run. You can't hurt your engine running too cold of a plug from what I am told....but you can burn a piston with too hot of a plug. Some folks like the racing 9's because if you are jetted too lean it will burn off the electrode before burning a piston.

 

Outstanding info.....I really appreciate this info!