i know this has been argued before but i couldnt find the thread.

im running NGK B5HS plugs in my 1600 sp with 009 and GT40 coil.

is this a good combo?

how does one select a spark plug based on application?

Not being privy to the former discussion, the B5HS is the NGK equivalent of Bosch's W8AC. For your combo, it's fine.

A rule of thumb is : Hot Motor = Cold Plug

B5HS is the middle heat range of NGK plugs, 1 being hottest, 10 being coldest.

For instance, some two stroke road bikes I owned used the pretty standard fitment B8ES.

My 851 Ducati used D9EV's, my former Mxer's and chook chasers used B9EV.

I personally find NGK's classification system dead simple.

Regards
Ctefeh

ok so if the 5 is the heat of the plug

what are the letters?

sori this is something i know nothing about...when u say its an "ok" choice do u mean its ok but u could make a better one?

Anthiron,
I have the book somewhere that explains it all but simply put....

First letter is thread size, B=14, D=10

There can be other letters after the thread size..e.g
P or PR or R

P=Projected Insulator (into the combustion chamber)
R=Resistor type plug

The numeric indicates heat range

next letter is thread reach or length, E=standard reach, H=short reach

Last one or two indicates electrode material and/or type
e.g V=small diameter electrode (maybe better material, it's been a long time since I owned said bikes), GV=small electrode of gold pallidium material, S=standard electrode

Your motor combo is pretty stock, so therefore a stock plug is a good choice. Using a "V" type (B5HV) is wasted money.

Let's say however you went 10:1 compression, goofy juice, wild cam with sewer sized ports/valves etc I would
start at "9" and work up the heat range.

Let me say categorically I don't build engines, it's just giving you a general idea.

Regards
Ctefeh

[ Edited on 23/2/2006 by ctefeh ]

upgrade to the NGK irridum, i used to have issues with plugs fouling, with the irridum, never had the problem. They cost a bit more ($20 each, but then i only replace them every year (15K to 20K)

aren't irridiums ment to last 100,000 km?

i use cheap extended tip plugs of the same heat range in my bus - 20, 000 km and still good. -> note this may cause premature engine death in some instances.

thanks for the info guys

yes They ar meant to, but i find i like to replace them at 20k, they look fine, but i just do it to be sure. I am only on my second set in 2 years...