sparkplugs?

[peteremsley]

Plug question for the experts.. Bike is R60/6 that lives at altitude -riding average about 5000-6000' What plugs should I use?

Here's my findings so far:

Owners manual has a strange Bosch number in it.

Bobs catalog says Bosch W5DC

Spares in tooltray - Bosch W6DC (I think Clymer agrees)

Bike has NGK BP7ES in it (seem to be equiv of W5DC)

Any help appreciated.

thanks-
peter.

[rocketman]

from the NGK web site

"Barometric Pressure/Altitude

Also affects the spark plug's tip temperature
The higher the altitude, the lower cylinder pressure becomes. As the cylinder temperature de-creases, so does the plug tip temperature
Many mechanics attempt to "chase" tuning by changing spark plug heat ranges
The real answer is to adjust jetting or air/fuel mixtures in an effort to put more air back into the engine"

"The spark plug has two primary functions:

To ignite the air/fuel mixture
To remove heat from the combustion chamber
Spark plugs transmit electrical energy that turns fuel into working energy. A sufficient amount of voltage must be supplied by the ignition system to cause it to spark across the spark plug's gap. This is called "Electrical Performance."

"The temperature of the spark plug's firing end must be kept low enough to prevent pre-ignition, but high enough to prevent fouling. This is called "Thermal Performance", and is determined by the heat range selected.

It is important to remember that spark plugs do not create heat, they can only remove heat. The spark plug works as a heat exchanger by pulling unwanted thermal energy away from the combustion chamber, and transferring the heat to the engine's cooling system. The heat range is defined as a plug's ability to dissipate heat."


I didn't realize the heat-range is a measure of how well they removed heat from the engine, always thought it was a measure of how hot they fired! Interesting.

I also have the NGK BP7ES in both my airheads a 73 R60/ and 78 R100/7 nad have been running with those for 5 plus years no problem as recommended by my machinic, so I'd say you have the right plugs.

Here's a link that explains how/what plugs do,

http://www.sentra.net/tech/sparkplugs.php

RM