Trackster Spark Plug

The Cushman Trackster Service Manual recommends Champion J2J (Discontinued)

Champion J2J Cross-References to:
Autolite = 353
Champion = J4C (825)
Bosch = W5EC
NGK = B7S

Other Spark Plug Information

Characteristics:
Diameter = 14mm
Reach (Distance into the cylinder head) 3/8" (.375") (9.5 mm)
Socket Wrench 13/16"
With Gasket

NGK says:
B = 14 mm
R = Resistor (Used to reduce radio noise or interference)
# = Heat Range (2 Hot - 10 Cold) (Looks like 7 is the right heat for the Trackster)
S = Standard 2.6 mm electrode
G = Racing use
V = Fine-wire electrode, gold-palladium

Heat Range
A hot spark plug has a much slower rate of heat transfer and is used to
avoid fouling where combustion chamber or cylinder head temperatures are
relatively low. A cold spark plug dissipates heat more rapidly in hot running
engines to reduce the risk of pre-ignition. The correct heat range is found
when the plug prevents fouling and does not contribute to pre-ignition or
pre-detonation.

Fine Wire Electrodes (V)
Spark plugs with small diameter center electrodes (.050") were originally
designed to improve starting and anti-fouling characteristics in small
two-stroke engines such as snowmobiles, chain saws, and dirt bikes.

In Theory:
Good NGK plug numbers would be:
Hotter Suggested Cooler
B6S B7S B8S
B6G B7G B8G
B6V B7V B8V
BR6S BR7S BR8S
BR6G BR7G BR8G
BR6V BR7V BR8V