R90/6 Texas Dirtbike rebuild

Discussion in 'Airheads' started by DiabloADV, May 9, 2012.

  1. Bigger Al

    Bigger Al Still a stupid tire guy

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    Yabbut it's pretty cool archaeology. :deal
    #21
  2. Chico

    Chico Thief and Saboteur

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    Oh, those muffs sounded nice. I liked the looks of the two pipes but thought a two into one would probably make more sense. I am really enjoying this thread and can't wait to see how the bike evolves.
    #22
    WooPig likes this.
  3. DiabloADV

    DiabloADV Semi-Occasional

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    My latest issue is that I need to replace the top triple clamp since it has a stripped handlebar bolt. I *thought* these were XR600R triples, since that's what the forks look like. But...XR600R forks are identical to the late 80's CR125R forks, and that tricked me. I ordered a new billet XR600R top clamp, only to find out it doesn't match the bottom (mine have less offset). Turns out I have CR125R forks and triples.

    So...I'm going to keep the new top clamp and buy a XR600R bottom triple off Ebay. The bike needs the additional offset that the XR600R setup has, since the current top clamp hits the tank. It should also quicken up the steering a little bit and only adds about $40 to my project.
    #23
  4. DiabloADV

    DiabloADV Semi-Occasional

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    A box with these in it arrived today. Taking heads in for valve refresh this week.

    [​IMG]
    #24
  5. chasbmw

    chasbmw Long timer

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    I really like the look of that bike, really rufty tufty. Do you have any contact with PO, might help with the archeological dig!
    #25
  6. DiabloADV

    DiabloADV Semi-Occasional

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    Yup, I've found the two guys that owned it before the guy I got it from. The original builder is somewhere in Santa Cruz -- used to work at the old Santa Cruz BMW, I'm told...
    #26
  7. tdrrally

    tdrrally Long timer

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    any newz?
    #27
  8. DiabloADV

    DiabloADV Semi-Occasional

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    I ordered aluminum fenders in early August from 7metalwest. Still don't have them...I need to call and ask why.

    Until I get the fenders and figure out the mounting and any fabrication I need to do, I can't really move forward. Motor is ready to assemble; transmission is overhauled. After the fenders are taken care of, I'll fine tune the shock and fork length to get the height I want (ie, lower than it is now).
    #28
  9. DiabloADV

    DiabloADV Semi-Occasional

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    Change of plan...I'm going to restore it back the way it was built. Only things I'm changing are (1) the back of the subframe to create a better rack for bags or boxes, and (2) lowering the ride height by about an inch. I might go with a Baja Designs round race light instead of the dualsport-style light on it now.

    Acerbis still makes all those plastics, so I can get new ones cheap. It'll be fresh and new! :clap
    #29
  10. b0mb3r

    b0mb3r Old Git

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    :wink: i'm in
    #30
  11. DiabloADV

    DiabloADV Semi-Occasional

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    As of this morning, I'm inclined to go with low-gloss black main frame and silver subframe. In the interest of function over form, the side panels will not come back. Don't see what function they really serve...

    Thoughts...?
    #31
  12. tdrrally

    tdrrally Long timer

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    where did the side panels come from?
    my version will be a two upper
    #32
  13. DiabloADV

    DiabloADV Semi-Occasional

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    Don't know about the panels. No identifying marks and they are heavily carved-up to fit. And they don't really fit well so I'm ditching them. On a real dirt bike they serve as covers over the pipes but they don't on this bike. Since its a solo bike I don't need covers over the pipes. I'm building a quick on-off standoff rack for when I have side bags loaded.
    #33
  14. DiabloADV

    DiabloADV Semi-Occasional

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    Build update. I spent the summer finishing the little Honda and riding my new Honda. Time to get back to the project.

    I've spent scores of hours staring at the bike, looking at pictures and thinking about what I want to do. Rebuild it as-is? Or...make it into what I would want to do if I started it myself? I settled on the latter. I want a bike that meets the following needs:

    - Good on the highway. Mountains are 3 hours from here, but there is a lot of really nice backroad and canyon riding nearby. So the bike has to be fun to ride day-to-day, not just on a once-a-year trip to Death Valley. But, I don't ride fast and I don't push the limits, so it doesn't have to be *that* good. Stable and steady.

    - Can carry gear. A top box (Pelican case), a soft tail bag, soft side bags. I like to go camping and I commute from time to time.

    - Moderate offroading ability. Fireroads, desert riding, mild technical stuff. Don't need to go fast offroad, and don't need to do the really crazy stuff. Places a 1200GS can go.

    And, function over form is the rule. If function is right, only then can a style decision enter.

    All that considered...the bike needs to change. First issue -- it's just too tall. 10" of ground clearance (without rider). 37" seat height. That doesn't fit with "highway friendly." And, my old-man offroad skills mean I need to be able to dab my feet through tricky parts. I started at the subframe, thinking that I needed to raise the shock mounts and lower the back end. But I looked at a lot of photos of stock and modified bikes and I don't think the rear is too tall. Here's a pic of the bike sitting with enough weights on it to match a built bike with a full tank and some camping gear:

    [​IMG]

    The swingarm angle doesn't look extreme to me. The passenger peg bolt hole is roughly in the centerline of the swingarm and I see plenty of bikes like that. So...I don't think I want to drop the back end. So...I took a closer look at the whole bike.

    [​IMG]

    And then dropped the front end 1.75"

    [​IMG]

    That looks more right to me. Ground clearance is still 9.25" -- plenty. Then I cut the subframe tube that the seat sits on, inserted some 1/2" bar to make a sliding arrangement, and pushed the back of the subframe down until I liked the seat setup better, and the rear rack flattened out.

    [​IMG]

    That looks good. Finally, threw the new fenders on there...

    [​IMG]

    Making progress! Need to learn something about shortening CR125 forks...
    #34
  15. Houseoffubar

    Houseoffubar HoFmetalworks.com

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    Damn, That looks hot shit! I really like it lowered a touch, it looks "just right":D
    #35
  16. LoJack

    LoJack Long timer

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    Cool, I was just looking at this thread earlier today. Glad you posted some progress.
    #36
  17. Stagehand

    Stagehand Imperfectionist

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    Thats your static sag but what will your race sag be?

    THe seat height might be much for a road bike at 37" but I wouldnt get rid of any ground clearance. Ground clearance is a gift from heaven :lol3

    SO it only looks like the bell housing on teh shaft was made longer in order to accomodate the longer swingarm?
    #37
  18. DiabloADV

    DiabloADV Semi-Occasional

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    Shock preload is in the middle of the range now. Should be plenty of room to dial in proper loaded sag. Actually, it was correct before I tore the bike down, so I imagine it will be correct after. I only lose 3/4" ground clearance. The seat came down to 34" mainly due to flattening out the subframe.

    I'll have the forks professionally shortened a bit and dialed in after the bike is fully built. Last thing that'll be done...

    Yes, the shaft was lengthened at the bell, not on the main shaft. Makes some sense...easier to have the result be straight and strong.
    #38
  19. Stagehand

    Stagehand Imperfectionist

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    It looks awesome. :deal
    #39
  20. orangebear

    orangebear Long timer

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    nice looking build you have there. and now wonder the seat was dropped as 37inch for the road is fine for a 6.5tall person only.
    #40