Help me find the right dirt bike for my next project

Discussion in 'Some Assembly Required' started by Pablo83, Apr 29, 2013.

  1. Pablo83

    Pablo83 Sleep, Wrench, Ride

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    I'm looking for a very light dirt bike rolling chassis for a future project. Here's what I need:

    Steel frame.
    USD forks.
    Aluminum rear subframe.
    Very light weight (like 125cc-two-stroke light)

    The '97 CR125 is almost perfect, but it has a steel rear subframe. The KX500 is right, but that's a little big for what I want. What other models fit these specs?

    Suggested bikes so far (more for my reference than yours):
    Small bikes (preferred):
    92-97 KTM EXC 125/200 (pro-link, 18" rear)
    98+ KTM EXC 125/200 (linkless shock)
    2003+ sx125 (19" rear)
    2002-2004 YZ 125/250

    Larger bikes:
    KX500
    98-04 YZ 400/426/450
    #1
  2. dentvet

    dentvet Long timer

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    KTM 125/200 chassis is a little smaller than the 250/300/380 chassis but all have your needs. PDS linkless swingarm started in 98, before that was linkage suspension.

    2003+ sx125 would give you access to all ktm wheels and forks from the most modern models.

    :ear
    #2
  3. Pablo83

    Pablo83 Sleep, Wrench, Ride

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    Thanks for the input. So you're saying the Pre-98 KTM (EXC I'm guessing?) 125, and 200 have what I want, as well as 2003+ sx125.
    #3
  4. sailah

    sailah Lampin' it

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    The yz450 frame is steel in the 04 vintage. Aluminum subframe. Usd forks. Linkage rear
    #4
  5. Pablo83

    Pablo83 Sleep, Wrench, Ride

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    So that would have been 98-04 for the YZ?
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  6. dentvet

    dentvet Long timer

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    I think all the 92+ ktm 2 stroke stuff have what you want. If you want linkage swingarm, you have to go earlier than 98. 98 and later have the PDS swingarm.

    All of them use the same rear axles 1992-2012. 19" wheels on SX and 18 on the rest.

    Pre 2000 have 17mm front axles, 00-02 have 20mm axles, 03-2012 have 26mm. 98+ all use the same triple clamps and brakes.

    Pre 2008, the 125/200 frames were smaller than the 250/300 so maybe they are lighter as well.
    #6
  7. MrPulldown

    MrPulldown Long timer

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    Why does the Al subframe matter. I have seen enough builds to see poeple make their own bolt on subframes. ANd I have seen enough of your work to know that it would not be a big deal for you to accomplish.

    Regardless intersested to see this new project.

    How do you find the time.
    #7
  8. Pablo83

    Pablo83 Sleep, Wrench, Ride

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    Weight. This bike will be designed with technical singletrack in mind:

    [​IMG]

    Some subframes (like my street tracker) are pretty simple and easy to build, but when you attach an airbox and plastics and a rear rack and such, they get a lot more complicated and time consuming.

    Well to start with, I'm going to try and find a bike that comes with an aluminum subframe so I don't have to build it myself. :lol3
    #8
  9. MrPulldown

    MrPulldown Long timer

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    If that truely the case, why a steel frame? Why not Al

    Neighbor of mine has CRF's. I have always thought those would be a hoot to trail ride.
    #9
  10. cedric

    cedric Been here awhile

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    Are you sure the '97 CR 125 has a steel subframe? I call BS on that. My '91 had an aluminum subframe.

    Either way, watching your thread with interest.
    #10
  11. sailah

    sailah Lampin' it

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    Guessing he wants to slot in a cool motor and will need to weld motor mounts to the steel frame?:wink:
    #11
  12. Pablo83

    Pablo83 Sleep, Wrench, Ride

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    Alu parameter frames block access to the carb requiring the rear shock to be removed to pull the carb. It's stupid, I hate it, and I spend most of the summer pulling CRF carbs for friends and clients so I don't need any more of that in my life.

    I love the CRF250/450X suspension. I think it is the best technical trail suspension available. If only they had a 6-spd gearbox, and a tranny that could stand up to highway use, and were air cooled, and had valves that lasted more than one season, and a carb that didn't take 3 hours to R&R... if only.
    #12
  13. Pablo83

    Pablo83 Sleep, Wrench, Ride

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    Well, I just had a '97 CR125 in the shop couple weeks ago. I thought it felt like a great chassis for this project so I put a magnet to the subframe and it stuck. So I'm led to believe it has a steel subframe. :scratch
    #13
  14. cedric

    cedric Been here awhile

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    Well that's hard to argue with. I would think a YZ 125/250 from 2002-2004 would be a good starting point, they are still making the same bike but with AL frame.
    #14
  15. JagLite

    JagLite Long timer

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    Hi Pablo,
    I wonder if you are thinking along the same lines I am?
    Like both of us building street trackers :D

    I bought a Suzuki RM250 (05) with a blown engine.
    Steel frame, aluminum subframe, USD forks, etc.
    I haven't checked, but have read it has Ti foot pegs even. :clap
    I do know it is amazingly light without the engine in it.
    Rolling it around in the garage it is like my mountain bike.

    Here is a rolling chassis shot:

    [​IMG]

    I want to put a Honda XR200 engine in it, if (when) I can find one.
    I believe the RM 125 uses the same frame, suspension, etc. but I don't know for sure.
    #15
  16. Pablo83

    Pablo83 Sleep, Wrench, Ride

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    Sounds like it; I love the reliability and low maintenance of the old air cooled thumpers, but their chassis' are too heavy and flexible. It's probably not hard to guess what engine I want to use.
    #16
  17. smithrod63

    smithrod63 Adventurer

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    Pablo I've seen a few of your other threads / bike builds and I gotta chime in with everyone else. I like your vision. I'm currently working on a similar project.

    I just picked up an 02 RM125 and have plans of putting a DR350 motor with a 441 kit (hopefully with E start too) - like you said 6 gears and good reliability.

    Anyways looking forward to it! Any Updates?
    #17
  18. Navin

    Navin Long timer

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    All Husky WR/CR125s from 1999 up fit your needs. RM125/250s from 1996 up too. The 96/97 had excellent conventional forks, as did 96 up to 1999 and some 2000 KTMs.
    #18
  19. Pablo83

    Pablo83 Sleep, Wrench, Ride

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    I have recently picked up both a kickstart DR350 and an e-start DR350. I hope to make a kick and e-start motor form these two and put it in a stiffer chassis. I have a lot on my plate right now, so don't hold your breath waiting for this project to get finished.
    #19
  20. Pablo83

    Pablo83 Sleep, Wrench, Ride

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    Thanks, I'll look into those.
    #20