Early '90s WR250 Yamaha

Discussion in '2 smokers' started by third eye, May 28, 2012.

  1. third eye

    third eye back road loon

    Joined:
    Sep 2, 2010
    Oddometer:
    199
    Location:
    Concord, CA
    OK, tell me about your two stroke version of this bike. I just bought a '93 version with low time on it. Bike rips. Have you changed anything? What do you recommend???
    #1
  2. Reino

    Reino Been here awhile

    Joined:
    Nov 21, 2011
    Oddometer:
    212
    Location:
    namibia
    you should re-title your thread like, wr250 2t info or something like that. I am a noob on this form as well, i had to learn the hard way.

    Unfortunately i cant help, i own a ktm 250sx and a 1983 tt600 and i have never seen a wr250 in person.

    Best of luck from a fellow noob :D
    #2
  3. GarageRat

    GarageRat Been here awhile

    Joined:
    Jun 24, 2010
    Oddometer:
    179
    Location:
    Western NY
    I had a '92-great bike! To make the bike more tractable for eastern (NY, PA, NJ) enduros & scrambles, I swapped out the aluminum clutch plates for steel (Yamaha replacement parts), this added inertia was noticeable, though i also added a 12 OZ. flywheel, which made the power deliver just electric. It was nearly impossible to stall the bike and perfect for gnarly, tight root infested trails. Yamaha also had an intake spacer that broadened the power delivery. In all, my changes made the bike trialsy, though reliable and easy to ride in enduros. Other more personal changes included a seat foam (taller) kit and pro-taper bars.

    With the mods removed, the bike was an able mx'er.
    #3
  4. third eye

    third eye back road loon

    Joined:
    Sep 2, 2010
    Oddometer:
    199
    Location:
    Concord, CA
    thanks for the info. I'm reading how changing the Mikuni carb out for a Keihin PWK carb transforms the bike. Low speed throttle is kinda iffy but the mid to upper range, the bike is a rocket. Having more fun on it than my YZ400F I used to have
    #4
  5. tHEtREV

    tHEtREV Captain Awesome

    Joined:
    Apr 14, 2007
    Oddometer:
    8,075
    Location:
    Middle Park, Brisbane, Australia
    I had a 98 for awhile (the same as the US 97model), but only kept it for a few months.

    Power was just a bit much and it was a bit loud for my liking.

    We also had a road registrable version, but unfortunately mine wasn't one of them...

    And considering I already had a KDX200 and a KTM200EXC (both road registrable here) I got rid of it.

    Fun bike though.
    #5
  6. PTRadam

    PTRadam Been here awhile

    Joined:
    Oct 3, 2005
    Oddometer:
    505
    Location:
    Williamsport, PA
    The 2 stroke WR 250's were basicaly the same bike as the YZ's of that era with a wide ratio transmission and a larger tank.
    #6
  7. gloud

    gloud Been here awhile

    Joined:
    Jun 22, 2011
    Oddometer:
    158
    Location:
    Western mass USA
    The only problem I had with mine (It was an 89 YZ250wrw) Was the flat slide carb was a POS (made for very hard starting) Went to a VM mikuni and solved the issues I was having. otherwise it was a matter of setting up the suspension for me and I rode the heck out of it. (oh and check the linkage bearings. mine where bad when I got it used from a bike shop. Just put it up on a stand and lift the rear wheel. should be no play.)
    #7
  8. third eye

    third eye back road loon

    Joined:
    Sep 2, 2010
    Oddometer:
    199
    Location:
    Concord, CA
    Just had the shock rebuilt and the ugly spring replaced since it was one size too weak for my weight. Hoping the stock fork springs can handle it after getting rid of the 19 year old mud....I mean, oil
    #8
  9. gloud

    gloud Been here awhile

    Joined:
    Jun 22, 2011
    Oddometer:
    158
    Location:
    Western mass USA
    I think it had a power valve? (Been a long time) just make sure it is not carboned up if it does. My 89 was a good bike. Fast
    #9
  10. Rot Box

    Rot Box Been here awhile

    Joined:
    Oct 31, 2010
    Oddometer:
    254
    Location:
    Northern Utah
    A friend of mine has a collection of WR250Z's from 92-97 he even has a 93 WR500 2T which is a ton of fun. 89's were known as the YZ250WR while later years were just WR250Z. Imo they are one of the best 2 stroke dirtbikes of all time even by todays standards. Unlike the YZ they had XC suspension, heavier flywheel with lighting coil, 18" wheel, larger fuel tank, wider gearbox along with a few other changes to make them more trail/xc friendly its really a shame they quit selling them in the US in 97. Unlike a lot of the enduro/xc bikes during the 90's the WR's were NOT detuned in any way shape or form--they rip and are every bit as powerful as the motocross bikes of the time.

    My biggest complaint with them is the stock fuel tank on the 94-97's... I don't know what Yamaha was thinking but its like riding with a beach ball between your legs :eek1 A good solution (like the later 4T WR's) is upgrading to the YZ seat and aftermarket desert tank.

    Imo the later round slide Mikuni carbs that came on the WR's were not too bad. If yours has one I'd try tuning it in first before you decide to bail on it. The earlier models had the flat slide TM which is a total POS. That said the PWK is an upgrade to anything Mikuni imo :deal
    #10
  11. third eye

    third eye back road loon

    Joined:
    Sep 2, 2010
    Oddometer:
    199
    Location:
    Concord, CA
    yes, this does have the power valve. I've richened up the float level and needle position since it was running on the lean side on the last ride. Going to test it out this friday. I had a problem back then on it stalling on long downhills with the clutch pulled in back then. Hope this helps
    #11
  12. third eye

    third eye back road loon

    Joined:
    Sep 2, 2010
    Oddometer:
    199
    Location:
    Concord, CA
    I was trying to remember something about this earlier model and that was it, the YZ250WR. Can't imaging what its like riding a 500
    #12
  13. Fubars

    Fubars What would Scoobydo?

    Joined:
    Aug 20, 2003
    Oddometer:
    1,789
    Location:
    Ventuna, California
    :eek1:eek1:eek1:eek1


    [​IMG]:eek1
    #13
  14. third eye

    third eye back road loon

    Joined:
    Sep 2, 2010
    Oddometer:
    199
    Location:
    Concord, CA
    I've tuned carbs before but this Mikuni VM38 is'nt cooperating, I can tell it's way too old school for this motor. I've got a Keihin PWK on order
    #14
  15. third eye

    third eye back road loon

    Joined:
    Sep 2, 2010
    Oddometer:
    199
    Location:
    Concord, CA
    It's taking forever for JD Jetting to receive new carbs from japan, Got the stocker to work for now.
    #15
  16. Rutsref

    Rutsref Been here awhile

    Joined:
    Sep 18, 2007
    Oddometer:
    104
    Location:
    California
    I had one of those in 94-97, raced prolly 25-30 D37 desert races on plus lots of trailriding, it never had any issues, only replaced the piston rings just before I sold it!! I still wish I'd kept it and plated it for dual sport riding while I could have. It's worth the $ effort to have the forks and rear shock revalved for plusher ride, enjoy the wide ratio trans and big tank, even used to be able to get 360 kits for them!! These bike rewarded aggressive riding style and had a good frame geometry for high speeds across rough terrain as well as great in the technical trails. ENJOY:clap
    #16
  17. third eye

    third eye back road loon

    Joined:
    Sep 2, 2010
    Oddometer:
    199
    Location:
    Concord, CA
    Yes, enjoying it much better with the new PWK carburetor and rebuilt/modified suspension.. Tried to install a full FMF exhaust I got from Dennis Kirk but it wouldn't fit. Had to send it back. It still runs fine with the stock exhaust
    #17
  18. fastdadio

    fastdadio Still gettin faster

    Joined:
    Sep 18, 2009
    Oddometer:
    2,403
    Location:
    Pinckney Mi.
    Did you have to drain those leaves out of the tranny? [​IMG] [​IMG] [​IMG]
    #18
  19. third eye

    third eye back road loon

    Joined:
    Sep 2, 2010
    Oddometer:
    199
    Location:
    Concord, CA
    ah, yeah....it shifts better without them........:lol3
    #19
  20. BOB RAMSAY

    BOB RAMSAY Not in the Clique -

    Joined:
    Jul 11, 2011
    Oddometer:
    362
    Location:
    Granville, Ohio
    . Bike rips. Have you changed anything? What do you recommend???

    Good question. I had/raced a '91, '93 & '95 back in the day. The had what I needed - bigger tank, wide ratio gear box, power for lights and THE MOST IMPORTANT - a side stand! (just kidding - but they do make life easier).

    What I would do?

    #1 - additional flywheel. It's been so long ago - Moose made what you want - it's a weld-on unit to your rotor. I only ran 4 oz. - I think they made 4-6-8. . .12 oz wheels. 4 oz worked for me - start easier, stall harder, hooks up in hte wet. Almost impossible to to stall it. And most of all - it just made it easier to ride - and I was all about that 20 years ago.

    #2 - keep lower shock linkage and main swingarm bolts clean and lubed (or buy a KTM) They did need upkeep and it's easy to ignore them. Also, change shock oil at least once a year (depending on how much you ride) - you can tell the difference. Fork oil - more than twice a year according you your riding hours.

    #3 - Pre-Mix - 40:1. I used Yamaha R, 2 stroke oil I believe it was. When I would 're-ring" the bike, I could clean the combustion chamber with a paper towel. The exhaust was still wet/rich - just wring out the RPMs as much as you can.

    #4 - replace rings on some type of schedule. No need to replace piston. I was told that a fresh piston will tend to wear the cylinder bore, much more than fresh rings. I had 300+ on the '91 top end, pulled and mic'd the cylinder - completely in specification - like the bottom number of the spec.

    It's fun just thinking back to those days - a lot of race prep for our Ohio enduros and hare-scrambles and many hours wiping grease from my hands. I think those bikes were around $3800 new back then.

    Have fun - and get that power valve open! :jinx
    #20