gatosbros XR600/650L scramblers

Discussion in 'Some Assembly Required' started by jesusgatos, Nov 28, 2011.

  1. jesusgatos

    jesusgatos fishing with dynamite

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    Building some custom XR600/650L-based scramblers; an XR600 for my buddy Seanito, a 650L for Hambone, and another XR650L for Grande. Sean wants something sort of like a street-tracker that he can rip around town on, Hambone would like more of a dirt-oriented scrambler, and Robo-Boogie and I are pretty dead-set on turning at least one of these into a longer-distance ADV bike. We might end up buying another one, because Grande and Hambone are going to be cruising together most of the time, so it really makes sense for them to be riding similar bikes. So for now I'm just going to focus on designing and building the parts they'll all share (custom tanks, subframes, seatpans, rear fenders, air boxes, etc.). Have been working on the tank for the last month or so, on and off. Excited about applying what I've learned about working with composites to a big project like this. Would like to hone my skills to the point where I can start designing rally kits and custom parts, so this is really just a learning exercise for me. Still making it up as I go, slowly figuring things out.
    #1
  2. jesusgatos

    jesusgatos fishing with dynamite

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    These are two of the three bikes we bought. The first is a stock late-model low-mileage XR650L (Hambone), and the second is what I'd call an average-condition late-model CA-plated XR600 (Seanito). The third is another late-model XR650L that we bought super-cheap because it wasn't running, but it's got a ton of nice parts on it (big-fin head, big-bore kit, Mikuni carb, full exhaust, Lindemann-Engineering lowered suspension, set of 18" street wheels, etc.). Swapped the wheels and suspension over to Seanito's bike so he can rail on that thing until it's time to tear his bike apart. Also bought an extra XR650L frame from FatherX to use for mock-up.

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  3. jesusgatos

    jesusgatos fishing with dynamite

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    First thing I did was take some pictures and make some rough sketches, just to get an idea of what I was working with. Do most of my design-work in SolidWorks, but even when I'm designing/building much more complicated stuff, I still start out with pages and pages of hand-scribbled notes. Not Chip Foose-style artistic renderings, as much as I'm just trying to work out rough dimensions and that kind of stuff. Quick-and-dirty. Except I'm not so quick about it...

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  4. jesusgatos

    jesusgatos fishing with dynamite

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    Decided to build the new tank on top of the old tank, so started by cutting it apart. Then made paper templates out of posterboard, using my sketches for reference, and then started transferring those to metal (am using 20-gauge scrap for most of this stuff). Ended up revising the profile of the tank several times, changing the arc of the backbone/spine and the radius on the lower/leading corners. It's usually much easier to remove metal than it is to add metal, especially when the trying to maintain symmetry, and I spent the better part of a day fitting the little bits of sheetmetal that are tack-welded to the lower/leading corners.

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    Mirroring templates, either by folding them in half or duplicating them, ensures the tank will be almost perfectly symmetrical. Went to a lot of trouble to do this. Probably a lot more work than I needed to put into it, but like I said, it's a learning process and I'm trying to develop techniques that will help me to do good work.

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    All this composite stuff is new to me, but over the years I've got to the point where I'm pretty fucking good at making templates. Funny how that seems to translate; I end up making templates for just about everything I design/build. Go through a lot of sharpies, scissors, and paper.

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    Took me a while to come up with some of these shapes. Think the fact that I've never done anything like this before had a lot to do with it, but it's also just sort of how I do things.

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    Seeing it in steel really helped me to visualize how it was going to turn-out. Really like the way it looked while it was all skeletal.

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    Instead of bringing the tank back to cover the upper shock mount and starting the seat where the tank ends, I decided to bring the seat forward/up the tank, more like a modern MX bike (going to use the stock tank-mount to hold-down the front of the seat). Had to cut-up the tank a little bit more to get the shape I wanted, but really like how this part of the tank has turned-out.

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  5. jesusgatos

    jesusgatos fishing with dynamite

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    When I was finally happy with the shape of the skeleton, it was time to add foam. Used 2lb foam that I bought from US Composites. Like working with this a lot more than the 2lb foam that I used to shape the handguard shields. Wrapped the tank with poster-board, set it on newspaper (to protect the concrete) and filled one half at a time. Am not too good at estimating the amount of foam needed yet, so had to pour foam several times. Not a real big deal, but it creates subtle differences in density and texture that make shaping a little bit more difficult.

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  6. jesusgatos

    jesusgatos fishing with dynamite

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    Cutting it down to the skeleton was quick and easy. Didn't try to put any contours into the foam, was mostly just connecting-the-dots with straight lines. Figured I'd rather build those contours back up with bondo, mostly to get a little more thickness/strength between the steel ribs.

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  7. jesusgatos

    jesusgatos fishing with dynamite

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    Was anxious to see what kind of capacity I was working with, so I stuffed the tank in a garbage bag and dunked it in a 55-gallon drum full of water. Looks like it'll hold about 3.4 gallons, and I'm going to add a bit more volume to the inside/underside of the tank. Pretty happy with that, and the tank is really low-slung, hugging the top-tube of the frame and the cylinder head, so it carries the fuel much lower than most of the tanks I've seen. Going to make some sort of some auxiliary rear-mounted tanks to extend range for a few of the bikes, so wasn't trying to build a super-tanker.

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  8. jesusgatos

    jesusgatos fishing with dynamite

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    After determining that I was satisfied with the basic shape and volume of the tank, it was time to start slathering bondo.
    Layers and layers and layers. These pics bring this project up-to-date, and now I'm realizing that I want to make a few changes. Going to re-work a few areas, bringing the high-point of the backbone/spine a little bit further back, and softening the top/front corners (shoulders?) of the tank. Hard to explain. Will have to just post more pics to show what I'm talking about.

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  9. Wattner

    Wattner Long timer

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    Far out!!!! I love custom stuff and you are going all the way!!!!

    Great projects for sure! Subscribed :D
    #9
  10. beechum1

    beechum1 Grimace Soup

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    yeah, me too. In.
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  11. tmotten

    tmotten Lefthand ride Dutchy

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    Lovin' it. :clap
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  12. srad600

    srad600 Been here awhile

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    very cool build. :freaky
    #12
  13. xr400r

    xr400r Long timer

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    keep it comin'!
    #13
  14. Dr LC8

    Dr LC8 ...soon or later

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    Mate...you are as insane as skilful:clap:clap:clap:clap:clap

    I am looking forward for more pics!

    Nic
    #14
  15. jesusgatos

    jesusgatos fishing with dynamite

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    Have spent the last few days working on the tank. Added a small lip to the top/front of the tunnel, knocked off the shoulders (top/fwd corners) and changed the profile of the tank by raising the backbone and making that a more gradual curve. Constantly trying to average-out the high/low spots, and have been struggling to maintain symmetry. This morning I started working on the underside of the tank, adding a little bit more volume and tweaking the shapes of things that would be problematic to make out of fiberglass. Tried adding talc to thicken-up the bondo and that makes if a lot easier to build-up some of the large radiuseseses and fill voids, etc.

    Looking forward to hacking off the stock the subframe. Went up to Bend and picked up my tubing bender, so have got everything I need to get into the next part of this project. Was tempted to try and make the whole kit a bolt-on deal, but I can make it so much cooler if it's all custom...
    #15
  16. sc-razor

    sc-razor Long timer

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    I knew Wattner would be first:D
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  17. jesusgatos

    jesusgatos fishing with dynamite

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    Just posted in another thread on thumper talk, asking about FCR carbs and tank clearance. Want to run FCR's on these bikes, the newer-style FCR (not the slant-body), but what size? What's the consensus? Two of the bikes are pretty much stock, and one of them is fully-built (cam, big-bore kit, ported big-fin head, full exhaust, etc.). Used a Noss adapter when I put an FCR on my 650R and was really happy with it. So figured I'd order a few more for these bikes. They do make them for this application, right?
    #17
  18. jesusgatos

    jesusgatos fishing with dynamite

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    paging cyclewizard...
    #18
  19. jesusgatos

    jesusgatos fishing with dynamite

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    Little bit of research dug up some good info on this subject (adapting FCR carb to XR650L).

    This post by Research Rat on TT regarding different sizes:


    And a long thread about jetting that I haven't had time to read yet.
    #19
  20. cyclewizard

    cyclewizard Long timer

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    Yep Sudco makes a nos adapter for the FCR41 but it's to short in my book for a good fit on the air box side but will work with a little muscle..:lol3 they should have made it longer like I'm going to do...
    I'm working on some aluminum billet intakes that can be ported to match the head porting at the monent.
    I like the idea of the billet intakes over the hard rubber ones, once you grind out the rubber ones to fit the race ported heads there's not much material left over. Besides that the aluminum won't crack and smoke your new motor that you just spent a grand or so on.
    Also the aluminum intake has a straighter shot going from the carb to the head and valves which will give you more POWER...:D
    The big bend on the oem intake hurts performance.

    I like the FCR45's over the 41's, it seems like the 41's run out of moe-joe in the upper revs and taller gears on the big block motors..for a 1mm or 2mm over high comp motor they work fine and I think they're the best carb out, almost like EFI they're so darn good.

    This is no lie once you pump up a XRL with a cam some head porting and some comp the CV carb performs quite well..when you pump one up to a big block motor they do even better....:huh
    #20