Jack up - When a club member sets a non club member straight.
Jap-Scrap - Insult - Japanese motorcycles or foreign made bikes.
Jesus Clip - A small clip that you WILL drop, followed by "Oh Jesus", 'cause you know you will never find it.
Jiffy - Side Stand
Jockey Shift(er) - The partner to the 'suicide clutch', this was another chopper convention, dispensing with the long shift rod and the lever and gate on the left side of the fuel tank. Instead, a short, about four to six inch, lever was fitted directly to the top of the transmission and shifted by the rider directly, by reaching under his left thigh. This made neutral rather easy to find and, in the hands of an expert, faster to shift than the stock foot clutch, hand shift mechanism.
Jugs - Cylinders
Jukebox - Any over-dressed bike
Just Given'r - Canadian. Expression for riding a motorcycle hard and/or fast.