Another I want to build a MX based adv bike

Discussion in 'Some Assembly Required' started by k555, Jan 23, 2018.

  1. k555

    k555 Adventurer

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    I love the Crf500l builds but as others have noted I want the weight and suspension of a MX bike. Weather it’s necessary or not is another discussion.

    I started thinking I was going to put the cbr500 in a modern crf. Thanks to this forum I hit the brakes on that one.

    I really like the WR YZ steel bikes but have seen the threads where others have failed.

    Should I just Buy an R3 motor so we can can actually get an idea what it’ll fit in?

    I’m pretty sure it would fit in the wr250r but it’s pricey, heavy and not suspended as well as I’d like.
    All input appreciated and welcomed!
    #1
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  2. larryboy

    larryboy Chopper Rider

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    If you want light weight you need to start with a light bike, maybe a 525/530 KTM. Put the CBR500 in it and you'll be under 300 pounds.
    #2
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  3. boatpuller

    boatpuller Long timer

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    Honest question here: What is the advantage of putting a CBR500 engine in a 525 KTM? (Presuming the KTM engine works of course.) BTW, while it is an awesome lightweight frame, it lacks support for luggage, so you'd need to address that to be a ADV bike.
    #3
  4. k555

    k555 Adventurer

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    Long service intervals, long motor life, 6 speeds wide ratio, min vibration, highway cruising for extended periods
    #4
  5. larryboy

    larryboy Chopper Rider

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    :stupid

    That sums it up @boatpuller .
    #5
  6. racingxtc7

    racingxtc7 Been here awhile

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    If I was starting over, I was thinking about buying a street legal YZ/WR 450 and buying a R3 then swapping the motors. This way you'll have everything you need. I find that trying to build a bike from parts always nickles and dimes you to death. The R3 with the 450 motor should sell easily and for more than a stock R3. It would be legal in CCS Racing's new classes, 500GT and 500 Superbike.
    #6
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  7. Salsa

    Salsa Long timer

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    I know a twin smoothes things out, but why not consider a KTM 390 motor. Lots of power, bottom grunt, and 80 pounds.

    Don
    #7
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  8. k555

    k555 Adventurer

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    Good news on the r3. Might be able to get it into a modern mx frame! If not a pre 06 wr/yz.

    I was out on the klr today, similar power to the r3. Do you think the r3 in a mx frame weighing in at about 260-275lbs will feel a lot faster than the klr?

    Attached Files:

    #8
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  9. Samtech79

    Samtech79 Two wheeled lunatic

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    Well... KLR's are only about 20hp to the wheel.
    It should positively smoke it.
    #9
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  10. 79thunder

    79thunder Been here awhile

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    Did you buy an R3 engine? If you haven't, let me know if you need any measurements.
    It is just a sweetheart of an engine, compact, lightweight, very nice power delivery and as mentioned smooth at high rpm and long service intervals.
    #10
  11. k555

    k555 Adventurer

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    I hope to win a salvage auction this week. I really think it’s gonna be great in a 275lb Bike! Any measurements you have , I’ll take!
    #11
  12. 79thunder

    79thunder Been here awhile

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    Yamaha R3 engine dimensions.jpg I hope this helps, I did my best, but let's call the measurements +or- 1/4".
    The width of the important pieces are about 8.5" at the valve cover and 15" total from the extreme outside of the sidecases.
    Let me know if there is anything else you need.
    #12
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  13. Salsa

    Salsa Long timer

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    I have looked for R3 engine weight and can not find it.

    Is there any chance you can get the weight?

    Don
    #13
  14. 79thunder

    79thunder Been here awhile

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    My engine is currently in the bike and mocked-up, wired up and running.
    When I pull it back out for final welding and paint, I can weigh it at that time. That likely won't be for a couple of weeks.
    If I had to guess, I would say somewhere around 95 lbs.?
    #14
  15. k555

    k555 Adventurer

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    Thanks for the picture! What do you have the r3 in?
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  16. Salsa

    Salsa Long timer

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    Thanks, I can wait.

    Don
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  17. brownvv

    brownvv Been here awhile

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    What bike are you putting it in? Do you have a build thread?
    #17
  18. 79thunder

    79thunder Been here awhile

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    Sorry, no build thread yet, I haven't had the time.
    It is not in a MX style frame.


    I did have a perfectly good '08 WR250 here.
    As in perfect. There wasn't a mark on it, less than 200 miles, I just couldn't convince myself to cut it up.
    I sold it for too much money before I could change my mind.
    It was mighty tempting, I think it would have fit quite well.
    The downside - aluminum frame and carb'd, but still doable.

    Fab work would be easier on an older steel framed WR or YZ. (of course when I looked for one, I couldn't find a decent bike for the money)
    The fuel injection swap however, would be easier on a newer fuel injected bike, or at the very least, use the tank and pump from a newer EFI WR.
    #18
  19. racingxtc7

    racingxtc7 Been here awhile

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    Sorry if posted. What's the weight? Thanks,
    #19
  20. k555

    k555 Adventurer

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    The R3 looks like it’s going to fit in a WR/YZ frame. Two issues I see(I’m still on paper, lost two auctions today for a wrecked r3).

    1. I will have to make the lower cradle wider to allow for the r3 sump. Easy peasy, I’m going steel frame.

    2. The counter shaft exits the R3 quite high. I was thinking of a combination of making the cylinder more vertical, thereby raising the sump some and then possibly a idler sprocket below the counter shaft.


    Is an idler sprocket a viable option? I can’t see it eating too much power?

    Does anyone know if we can put a flat oil pan on it the r3 like the crf500l guys do?

    Thanks for everyone’s help so far. I really would be sitting in front of a bunch of useless parts if not for you guys.
    #20