1. 2 Stroke Husqvarna Motorcycles Made In Italy - About 1989 to 2014
     WR = 2st Enduro & CR = 2st Cross

125-200cc What does the "D" stamp in the bottom of my cylinder indicate?

Discussion in '2 Stroke' started by Aksus, Jan 16, 2022.

  1. Aksus Husqvarna

    Husqvarna Motorcycle:
    2005 CR 125
    I just took apart my Husqvarna CR 125 top end and noticed that there's a letter "D" stamped on the bottom of the cylinder. If I've understood correctly the letter "D" indicates the size of the cylinder and at the same time the size of the piston I should be running, so if I get a new piston right now I should be buying a D size, correct? If this is the case, what is the point of making different size cylinders (A, B, C...) if the base volume is still the same (124cc)?
    Aksus, Jan 16, 2022
    #1

  2. Dirtdame Administrator

    Location:
    Rock Springs Wy
    Husqvarna Motorcycle:
    11 WR300,13 WR125,18 FE501
    Other Motorcycles:
    17 Beta Xtrainer
    The letters go up in increments of a one hundredth of a millimeter, or slightly less than half a thousandth. When mass production produces slight variances in the cylinder diameter, piston skirt sizes can also vary to match the specifications for clearance. The best way to determine what piston goes to what cylinder is still going to be using a dial bore gauge, t-gauge and micrometer to measure the piston at the lowest measureable point on the skirt, and the cylinder at the top. You can also use a a feeler gauge to get close enough, by slipping the piston into the cylinder, and seeing where it gets snug. The bottom of the cylinder will always wear the most, front to back. Piston skirts are wider at the bottom of the skirt than they are at the top. The top is small, to allow for heat expansion.
    Dirtdame, Jan 16, 2022
    #2