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

250-500cc Correct Orientation For Replacement Piston Rings?

Discussion in '2 Stroke' started by mr_manny, Dec 13, 2021.

  1. mr_manny Husqvarna
    A Class

    Location:
    Jalisco, Mexico
    Husqvarna Motorcycle:
    wr250
    I picked up some replacement rings online for my new-to-me wr250.

    The issue is, there doesn't seem to be any sort of indicator for proper orientation.
    The rings are flat, but do have a subtle twist to them.

    Does the sharper edge face up towards the head, or down?
    Thanks
  2. mr_manny Husqvarna
    A Class

    Location:
    Jalisco, Mexico
    Husqvarna Motorcycle:
    wr250
    ​One side does have a sharper edge...but no marks visible :(

    ring02.jpg
    ring01.jpg
    ​
  3. mr_manny Husqvarna
    A Class

    Location:
    Jalisco, Mexico
    Husqvarna Motorcycle:
    wr250
    Found some markings...my mistake.
    Since there are indeed markings, they represent the top-side?
    ring03.jpg
  4. Picklito Husqvarna
    Pro Class

    Location:
    Washington
    Husqvarna Motorcycle:
    430, 430, 430, ,400, 175
    Other Motorcycles:
    KTM250xc, KTM500mx, KTM440exc
    Yes. In every case I've ever seen, markings go up. They can be frustratingly difficult to see!
    mr_manny likes this.
  5. mr_manny Husqvarna
    A Class

    Location:
    Jalisco, Mexico
    Husqvarna Motorcycle:
    wr250
  6. Dirtdame Administrator

    Location:
    Rock Springs Wy
    Husqvarna Motorcycle:
    11 WR300,13 WR125,18 FE501
    Other Motorcycles:
    17 Beta Xtrainer
    Did you install the ring into the cylinder and measure the end gap? Was the end gap too small, or did you just remove material to help with installation?
    Picklito and 2premo like this.
  7. 2premo Husqvarna
    Pro Class

    Location:
    Northern NV
    Husqvarna Motorcycle:
    98 WR360, 1987 WR430, 1988 XC430
    Other Motorcycles:
    Sherco 300, 2002 KTM 380EXC

    what's easier is most if not all 2 smoke pistons have a dowel in the ring groove to keep the ring in the correct location so as to prevent ring ends from catching a port
    so just use the index and it will also show you which way is up on the ring
    Picklito, mr_manny and Dirtdame like this.
  8. 2premo Husqvarna
    Pro Class

    Location:
    Northern NV
    Husqvarna Motorcycle:
    98 WR360, 1987 WR430, 1988 XC430
    Other Motorcycles:
    Sherco 300, 2002 KTM 380EXC
    if the piston ring is too tight it might not be the right one
    Dirtdame likes this.
  9. Dirtdame Administrator

    Location:
    Rock Springs Wy
    Husqvarna Motorcycle:
    11 WR300,13 WR125,18 FE501
    Other Motorcycles:
    17 Beta Xtrainer
    Exactly what I was thinking. End gap is the first thing I would check if I had trouble installing the piston assembly.
    2premo likes this.
  10. 2premo Husqvarna
    Pro Class

    Location:
    Northern NV
    Husqvarna Motorcycle:
    98 WR360, 1987 WR430, 1988 XC430
    Other Motorcycles:
    Sherco 300, 2002 KTM 380EXC
    was this a 2 smoke ring you modified?????
    the point at the outside of the ring is set to the cylinder diameter, the point on the inside is set for the dowel, did you correct both???
  11. mr_manny Husqvarna
    A Class

    Location:
    Jalisco, Mexico
    Husqvarna Motorcycle:
    wr250
    There was virtually no gap, as I ordered rings +.50, so they were tight.
    All measurements were performed with the rings about 20mm into the cylinder with a feeler gauge.
  12. mr_manny Husqvarna
    A Class

    Location:
    Jalisco, Mexico
    Husqvarna Motorcycle:
    wr250
    I used Honda cr250 2 stroke rings.
    I don't have an accurate bore gauge, so I ordered 66.5mm bore rings to play it safe.

    There was enough room to clear the piston-ring grove dowel, so I didn't need to modify the inside (stepped) edge.

    Now you have me worried there isn't going to be enough clearance for the piston grove dowel during heat expansion...
    2premo likes this.
  13. Picklito Husqvarna
    Pro Class

    Location:
    Washington
    Husqvarna Motorcycle:
    430, 430, 430, ,400, 175
    Other Motorcycles:
    KTM250xc, KTM500mx, KTM440exc
    Hmmm. I like the 0.4mm end gap. Might be worth checking the dowel gap. Air cooled motors do heat those rings! And too little gap can be a cause of new top end failure.

    I give you Major Kudos, however, for asking the questions and wanting to get it right!
    mr_manny and 2premo like this.
  14. Dirtdame Administrator

    Location:
    Rock Springs Wy
    Husqvarna Motorcycle:
    11 WR300,13 WR125,18 FE501
    Other Motorcycles:
    17 Beta Xtrainer
    :eek: Not sure I would use a ring that was not designed specifically for the bike brand and model. Rings are designed to work with a particular piston and even the engine characteristics. The ring radius may be different.
    2premo likes this.
  15. mr_manny Husqvarna
    A Class

    Location:
    Jalisco, Mexico
    Husqvarna Motorcycle:
    wr250
    Since Honda and Husqvarna 250 2 strokes share the same cylinder bore, I didn't think it would be an issue.

    I will keep everyone posted on my experiment with Honda piston-rings.
  16. 2premo Husqvarna
    Pro Class

    Location:
    Northern NV
    Husqvarna Motorcycle:
    98 WR360, 1987 WR430, 1988 XC430
    Other Motorcycles:
    Sherco 300, 2002 KTM 380EXC
    what year Honda rings and what year Husky?
    early Honda was chrome and Husky was Nikasil
    so totally different cylinder conditions
  17. 2premo Husqvarna
    Pro Class

    Location:
    Northern NV
    Husqvarna Motorcycle:
    98 WR360, 1987 WR430, 1988 XC430
    Other Motorcycles:
    Sherco 300, 2002 KTM 380EXC

    as well as the cylinder coating
  18. mr_manny Husqvarna
    A Class

    Location:
    Jalisco, Mexico
    Husqvarna Motorcycle:
    wr250
    Very good points 2premo.
    Thanks for the reply.

    husky is an 07

    Looks like 86-2004 Hondas have Nikasil coated bores.
    I reached out to the seller asking which years the rings are designed for.

    Keeping fingers crossed.
  19. 2premo Husqvarna
    Pro Class

    Location:
    Northern NV
    Husqvarna Motorcycle:
    98 WR360, 1987 WR430, 1988 XC430
    Other Motorcycles:
    Sherco 300, 2002 KTM 380EXC
    if the cylinder was Nikasil then you are good, they definitely used a different ring
  20. Dirtdame Administrator

    Location:
    Rock Springs Wy
    Husqvarna Motorcycle:
    11 WR300,13 WR125,18 FE501
    Other Motorcycles:
    17 Beta Xtrainer
    Think about it though. The ring set was .50 over....so for a cylinder that can be bored.