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

250-500cc Wr 250 Engine Rebuild Advice

Discussion in '2 Stroke' started by Dan131.2013, Jul 16, 2021.

  1. Dan131.2013 Husqvarna

    Husqvarna Motorcycle:

    I am rebuilding my recently acquired WR 250 and have a couple of engine questions.
    The bike is in the process of being rebuild / supermoto'd so i will get some photos up soon of the project.

    My first and foremost question is about the spacer that sits behind the primary gear on the end of the crank shaft. On disassemble there was no o ring, and on all the parts drawings i cant see an o ring - however on the other 2 strokes i have built there always has been to stop air getting sucked through the spacer and into the crank case.
    I have attached a photo of an exploded diagram where i expected to see an o ring.

    Secondly, when doing a leak test i left the power valve covers off. When i pressurize the engine it leaks straight out through the power valve o ring seals.
    It has new o rings so i assume they're not an air tight seal so i can put the power valve covers on and do the test again?

    Hope that all makes sense :o


    Attached Files:

  2. Dan131.2013 Husqvarna

    Husqvarna Motorcycle:
    For anyone interested, or that stumbles across this thread in the future…

    As previous 2 stroke I have rebuild have had an o ring on this spacer - I assume this one should

    I have a couple of o ring sizes to try tomorrow and will update with results
    steadydirt likes this.
  3. rancher1 Husqvarna
    Pro Class

    No oring necessary.
    Dan131.2013 and steadydirt like this.
  4. Dan131.2013 Husqvarna

    Husqvarna Motorcycle:
    Thanks Rancher1,

    I bolted everything together and pressure tested the engine with no o ring on the spacer.

    Soapy water around the bolted up spacer / primary crank gear and no bubbles.
  5. Hurky Husqvarna
    AA Class

    Husqvarna Motorcycle:
    WR300 2010
    Other Motorcycles:
    Yamaha WR480F 2008
    Hi Dan, I've re-read my engine rebuild post and also checked the owner manual and parts diagram of the engine and there is no O ring on the crankshaft end, there are flat surfaces that makes the seal, make sure those surfaces are clean and flat and there should not be any leaks once torqued town to the correct specs. You could put a tiny bit of some thick grease on those contact surfaces if you like to probably improve sealing, but it's normally not needed.

    Cheers .
    gaz likes this.
  6. Dan131.2013 Husqvarna

    Husqvarna Motorcycle:
    Cheers for getting back to me Hurky,

    I have got the engine back together now and its back in the bike and running well.

    Thanks for the infomation, i will start a new thread with some photos of my supermoto project :)
  7. Dan131.2013 Husqvarna

    Husqvarna Motorcycle:
  8. Sonnie Mee Husqvarna
    A Class

    Husqvarna Motorcycle:
    Team Motorex Husqvarna CR125
    No o ring required and those o-rings on the exhaust valve are pesky if they don’t seat correctly you can get issues we have to check double check and triple check they seat right
    Glad your engine is back together and running