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

250-500cc Wr250 powerband racket?

Discussion in '2 Stroke' started by R_Little, May 18, 2010.

  1. R_Little Husqvarna
    Pro Class

    Location:
    NJ
    My 04 WR250 has a noise problem! It may be powervalve related.

    I run a PC pipe and both the TMX and PWK carbs

    It pulls from idle quite nicely with big power into the mid range and is rather quiet.

    Once it hits the upper mid it becomes super loud like the muffler fell off. Power falls off like it is running lean and the bike remains loud and kinda flat until I shut it down and decellerate for a while then it instantly becomes quiet like the silencer was snapped back on and the strong mid mid range power returns.

    Hold it open for a while in a sand wash and it'll remain noisy and flat for quite a while. Kinda like pressure has to be bled off until it returns to normal. Short applications of WFO are fine and the bike hauls....only long WFO straights are a problem like pressure is building up. the change to good power is instant and you can really hear the DB's drop.

    It is really like the silencer is being blown off the pipe but everything is tight and even a rubber gasket on the silencer joint does not make a difference.

    oh, a fresh repack on the silencer makes no difference.

    The PV's are clean.

    any ideas......
    R_Little, May 18, 2010
    #1

  2. Motosportz CH Sponsor

    Location:
    Vancouver WA
    Husqvarna Motorcycle:
    2021 TE250i, 570 Berg, 500 KTM, 790R
    Other Motorcycles:
    many
    Maybe you should try running one carb at a time :D

    My buddies 07 WR250 is to loud too. Kinda the same thing. OK at idle but when he is on it it is loud especially for a 2 stroke.
    Motosportz, May 18, 2010
    #2

  3. BILLF CH Sponsor

    Location:
    BMP Husqvarna, Salem, OR USA
    Husqvarna Motorcycle:
    92WXC350 /Lamson CR250/701 Vitpilen/
    Other Motorcycles:
    Triumph900 Scrambler 1200 HD Nightst
    any chance the header pipe is moving out at the exhaust port under full power ?f
    might check your flywheel key also in case timing related? billf
    BILLF, May 19, 2010
    #3

  4. woodzi Husqvarna
    AA Class

    Location:
    Waterloo, ON
    Sounds like your power valve is sticking in the open position.

    Mine did that - it was really loud and had no bottom end. After some time at low rpm the valve would close and the engine would return to normal until the valve stuck again. It took a very thorough cleaning to get it to run properly.
    woodzi, May 20, 2010
    #4

  5. R_Little Husqvarna
    Pro Class

    Location:
    NJ
    That is exactly what is happening.

    The problem is the PV is clean wit new bearings and everything.

    I did have some wear on the side valve bushings so I'll look at that.

    Thanks!
    R_Little, May 20, 2010
    #5

  6. letitsnow Husqvarna
    AA Class

    Location:
    mn
    Husqvarna Motorcycle:
    FC250
    Other Motorcycles:
    CBR600F4
    It sounds like you have already found your problem.

    Just another thought for others that are noisy - my FMF Gnarly rattles around at a certain rpm. I've tried heaver springs, repositioning the pipe hangers. The only thing that stops the rattle is to have my buddy hold his boot on the pipe while I rev it. Too bad he can't run very fast on one foot...
    letitsnow, May 21, 2010
    #6

  7. ARod2000 Husqvarna
    AA Class

    Location:
    Georgia
    Huh! I just realized that was what was happening to mine too. I thought the PV wasn't opening because there was no hit. But, now thinking about it, it was open the whole time. This from the last GNCC I did, which was a 3+hr race WFO. I cleaned the PV and fixed it....but I had technically diagnosed it backwards. Good info.
    ARod2000, May 21, 2010
    #7