Yamaha WR250R Mega Thread

Discussion in 'Thumpers' started by Sock Monkey, Apr 7, 2008.

  1. debaisley

    debaisley Long timer

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    it will certainly replace the drz , and dr350 , if you race , keep the kdx , if not , WR is a fine trail machine.
  2. DougZ73

    DougZ73 Fading off.........

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    I went from a 2000 DRZ 400 to the 2010 WR250R, and have not looked back. IMHO, only thing the WRR really needed was a shock rebuild....if you do any hard style riding.
  3. HardWorkingDog

    HardWorkingDog Harvey Mushman

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    It's a combination of art and science; a bit seat of the pants "how's it feel with this change" plus dyno runs, exhaust gas and temp. analysis and experience.

    I did come across this very cool tool in Motorcycle Consumer News--an NGK air-fuel monitor. It's got a wide-band O2 monitor that'll work from 9.0 - 16.0 afr's, about $260. You'd need to drill and weld the sensor bung into the header pipe, but this seems like a pretty inexpensive way to figure out exactly what's going on with fuel delivery over the full range of throttle settings.

    http://sparkplugs.com/more_info.asp?AAIA=&pid=20509

    I'm no expert, but from others who are you're looking for afr's in the range of 13.0 : 1 for best performance, below the ideal 14.7 : 1 ratio...
  4. bhd1223

    bhd1223 Been here awhile

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    Just a note on the 14.7:1 ratio. I'm fairly certain this is the calculated ideal ratio because of the typical standard units used and there are 14.7 psi (pounds per square inch) per atmosphere. 14.7 psi : 1 atm

    So now onto my question. I just received my new bars and associated odds and ends but I noticed a problem. The inside diameter of the new bars are too small for the old bar end hand guard attachment. Am I supposed to remove the rubber sleeve for it to fit or find one slimmer? I'm going from the stock bars to Tusk Chub bars and use Tusk D-Flex hand guards. Maybe now is the time to spring for Cycras with a triple clamp mount? Will I run into the same problem with those?

    Thanks for any help you can provide with my dilemma.
  5. freetors

    freetors Been here awhile

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    Are there any companies that sell springs for our suspension? Specifically for the forks. I only weigh about 145 with gear and I'm only getting about 1.5-2 inches of sag on the front. The forks seem pretty harsh on almost all bumps and they are not very supple or plush. The rear spring is a little too stiff but I was able to get the proper amount of sag on the rear, albeit it s near the limit of preload adjustment.

    I'm more of a DIYer so dont tell me to just send my stuff off to some suspension tuner. I dont feel like a complete shock rebuild or anything like that are necessary for me now.
  6. HardWorkingDog

    HardWorkingDog Harvey Mushman

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    I don't know if that's just a weird coincidence, or maybe if I took the time to figure out all the unit conversions it would turn out that we're really saying the same thing. Or not.

    Anyway, the stoichiometric ratio of 14.7 parts air to 1 part fuel is what would be needed to just exactly burn every bit of fuel, completely. In a perfect world.

    Modern fuel management systems try to get the air-fuel ratio as close to that as possible to minimize exhaust pollution, while still providing enough power to satisfy the need for speed. And sacrifice performance in the process. Racers, as an example, don't aim for 14.7 to 1.
  7. bhd1223

    bhd1223 Been here awhile

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    How did you get the proper sag in the rear? I'm about 180+ with gear and can't get close to static sag but have good free sag at the maximum spring length/minimum preload adjustment. Preload is the 8.5" max spring length as specified in the service manual. I'm about 1" (25mm) or a little less in free sag and 2.25-2.5" static sag. I'd like to be more around 3.25-3.5" static sag. We do have 10.6" of travel so 1/3 is around 3.5"
  8. freetors

    freetors Been here awhile

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    I only take two measurements when I set my sag: with the suspension completely unloaded and with my weight on it. I measured from the top of the swingarm directly above the axle up to the top of the helmet lock simply because its easy to measure from those points while sitting on the bike.

    I've never measured "free sag". Would somebody like to explain the significance to me?

    I have between .25 and .5 in of threads left at the top of the shock but am getting 3.5" sag at the wheel. With the shock in the stock preload setting I had about 2.5" of sag. At first I thought I would have to take the preload to the minimum but that gave me roughly 4" of static sag and felt really wonky just sitting on it.
  9. Machtig

    Machtig Been here awhile

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    Hi all. I'm in Vegas and just checked in for the Vegas to Reno race. I'll be on the trusty WRR, #O31, Ironman Expert. The expert part, thats funny :lol3 My goal is to not get run over by trophy trucks and to finish in 15hrs or less. Its 550 somthing miles long fyi. Bike is stripped to the bare necessities. I'm running Michelin Deserts with a HD Michelin tube in the rear and a Michelin BIB Mousse up front. I've got two spare air filters, a spare chain slider, and a spare fuel pump.

    You can track my progress HERE enter password: wr250r and if it asks you to open page securely, click NO I should leave the start line around 0630 pacific time, maybe later as my lucky self drew next to last starting position in my class. :puke1

    I'll post more pics later, I've never been to a race this big. This is going to be a riot.
    [​IMG]
  10. bhd1223

    bhd1223 Been here awhile

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    If you are getting the proper static sag then I think you are beyond the allowable maximum spring length/minimum preload as stated in the service manual. I did this myself when setting my sag but then checked the spring length and it was longer than the maximum so I shortened up to the max length/min preload and am where I sit now.
  11. bhd1223

    bhd1223 Been here awhile

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    Good luck bud. Sadly I didn't get my R² until a couple years after leaving Vegas. The only thing I rode around there was my mini KLX110. The desert is a riot. Have fun and stay safe.
  12. cinco

    cinco bageldog

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    You need to do a Ride Report on this one! Good luck! :lurk
  13. freetors

    freetors Been here awhile

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    Well I checked my "free sag" with my current 3.5" static sag and I get a whopping 1.75"- I think I'll go and check my spring length. Its looking like I need softer springs with more preload. But my front suspension bothers me more.

    EDIT: I'm right at the soft preload limit of 8.5" of spring length.
  14. emerson.biguns

    emerson.biguns All idiot, no savant

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    :clap

    I'll be watching. Good luck.



    .
  15. GotMojo?

    GotMojo? Long timer

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    Agreed!
  16. Reposado1800

    Reposado1800 Juicy J fan!

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    I followed the instructions you posted and they worked like a charm. My bike was at -1 from the factory and I bumped it up to +2. No more lean surging.
  17. GSBS

    GSBS FunHog

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    Glad it worked for you. Were I you, I'd still pull the plug and have a look for peace of mind. Mine was perfect. YRMV.

    Mind you, I'm not saying this is the "only" or "right" way. But it's worked for me for almost 8K miles without issue.
  18. onetravdown

    onetravdown I can't ride where?

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    Thanks to Simmons1 for trading his Safari for my IMS. For the type of riding I do the IMS was just to much tank. I think the Safari will be perfect for me. He lives down in TX so the IMS will give him the much needed fuel capacity for his area. It was the perfect trade! :thumb

    I went from this 2 weeks ago
    [​IMG]

    To this last weekend
    [​IMG]

    And finally to this tonight. I think I'm done changing its 'clothes' for a while. It's tiring enough changing it's shoes twice a week.
    [​IMG]
  19. onetravdown

    onetravdown I can't ride where?

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    Good luck and ride safe!! I'll look forward to the ride report!
  20. Krabill

    Krabill Long timer

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    Good luck!!



    :lurk