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  1. #1

    Wander over from Customfighters

    Figured I'd check in here. Am a poor boy, so no full member for me (my ViP at CF was sponsored by a friend). Relatively new to building. Was riding from 1990-95, then dropped it, and bought a junker in 2010 to ride, and was given another with no title on the condition I "do something cool with it". I'd never customized a bike before, but I did a lot of welded sculpture in the 00's, and figured I could transfer the skills.

    I got sucked in pretty hard and spent 6 years building a custom suspension system (and a lot of other shit to fit around the changes that implied, and get the ergo I wanted). When I finally got done with it, [url=http://www.customfighters.com/forums/showthread.php?t=135105]I won FoTM over at C.

    I should probably dump bike pictures and discussion in the proper forum, but with an intro like that it's rude not to include a couple pictures, right? I call it the SECApocalyopse. Feel free to hate it, it's got something to piss of fans of any style. I call it a street fighter because that's what most inspired me. That and, obviously, Mad Max, so its nice to know there's a fighter community in Australia.



    Last edited by sebwiers; 05-12-2017 at 07:48 AM.

  2. #2
    Bloke with a smaller stick rod185651's Avatar
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    Welcome mate, great to see you over here matey

  3. #3
    Bloke with the stick Gix11's Avatar
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    Hey mate, welcome aboard. That is some radical build and hence I love it! So much work. The questions on that front end could go all day. How is the final ride? ...and is the tank at the back cut up to look like panniers? Love the free-form approach.

  4. #4
    ASF Gold Full Member LKC73's Avatar
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    Welcome. Wow that is out there! I wonder how she rides as well. Very interesting build.
    Street Monster GSXR 7/11 water heater!
    Project R1 underway, The "Raven"

  5. #5
    Aussie Streetfighter Hooligan
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    Is that a BMX stem and bars?
    Bars used as bark busters????
    Pushy tubes used as frame wrap

    I think you are right about the tank Si, good thinking outside the box.

    It's ugly (to me) and I like it!!11!!1!!11!

    What's going on with the air cleaner?
    there is a foam(???) part between the carbs and the pod.

    Front wheel path, is it vertical or set on an angle?
    There is a lot going on with the front and I can't quite work out the linkages.

  6. #6
    Quote Originally Posted by Gix11 View Post
    Hey mate, welcome aboard. That is some radical build and hence I love it! So much work. The questions on that front end could go all day. How is the final ride? ...and is the tank at the back cut up to look like panniers? Love the free-form approach.
    Ask away, that's why I post.

    It rides amazingly well, or at least rides the way I expected / wanted it to. I don't have much to compare to to other than other busted-ass 80's bikes I've ridden - So anything I say could maybe be swayed by a second opinion, if I find somebody else brave enough to ride it.

    My main worry when building was that the steering would feels weird / sloppy / vague. Unless some of the linkage bolts are loose, that's a non issue, the front end feedback is very good. Better than anything I've ridden by far (including my near mint 1985 FJ1100).

    The first few rides on it were crap (the steering damper was causing HUGE bump steer and the spring was way to soft, meaning there was lots of bump) but it was still ridable (and thank god, because I was picking it up from a shop that dyno tuned it and riding home on the highway).

    Removing the steering damper fixed half the problem, swapping the shock (2000ish gsxr 1000, 650 lbs / in) for something stiffer (Hybausa Gen 2, 850 lbs / in) helped hugely as well. I've only had a few short rides since doing that, and just got hit with a snowstorm, so...

    My plans are to hope the snow melts and ride a few more times, then take it indoor flat tracking and ice racing in Feb! So I really was rushing (and still will be) to get set up for that!

    I'm still dialing it in. I recently bumped the anti-dive up and pulled the trail back down (from 4" to 3") and that was a big improvement. I plan to fabricate a new lower link (the one the pull rods and shock mount to) because the geometry of the link it has makes the wheel rate regressive (stiff at first, then softer) and with a better setup I can make it linear AND pick up an extra 30mm of travel.

    The fact that it already feels damn good (I've ripped it down a pothole strewn twisty in my neighborhood, intentionally hitting bums while making manuevers, and taken it over speed bumps at 20 mph) without being dialed in or even having ideal link setup makes me think its got real potential.

    Its still got big wheels (19" front), long wheelbase (60"), and lots of weight (500 lbs), but I'm also a big guy (6'3", 220 lbs) so the ergo works out great.  It feels ... well, like it was made for me.
    Last edited by sebwiers; 07-12-2017 at 04:56 PM.

  7. #7
    Quote Originally Posted by latheboy View Post
    Is that a BMX stem and bars?
    Bars used as bark busters????
    Pushy tubes used as frame wrap

    I think you are right about the tank Si, good thinking outside the box.

    It's ugly (to me) and I like it!!11!!1!!11!

    What's going on with the air cleaner?
    there is a foam(???) part between the carbs and the pod.

    Front wheel path, is it vertical or set on an angle?
    There is a lot going on with the front and I can't quite work out the linkages.
    Yeah, the BMX stem is actually clamped to a bicycle steerer that goes through the motorcycle head tube, with the bicycle headset bearings sitting in reducer cups to work in the motorcycle head tube. The legs of the bicycle fork are cut off. This whole setup is independent of the fork that holds the wheel (has no suspension loads on it) so it just needs to be strong enough to allow me to steer.

    There's a linkage setup from the BMX stem to the fork that allows the bars to steer the fork while allowing the fork to move up and down bu the bars stay stationary, without introducing measurable bump steer. The linkage concept I used is similar to the one described in this video (I'm on the same mailing list as the builder in the video).



    And yeah, for ergo sake I welded new grip positions on the BMX bars, and left the original grip positions as bark busters / lever guards.

    The bike tubes wrapping the frame are what holds my wiring in place. I re-used the stock harness (heavily chopped) so there's a fair bit of extra wire length (and some entirely un-used wires). Shockingly, it has working lights (headlight, tail / brake / plate illumination / even a fog light) and horn, and they all use the stock barcons. I had to at least do that much for it to be legal / safe for road use.

    The tank on the rear was the bikes original tank, was to rusted to use, so I cut the bottom out and used it to cover the rear wheel. Fender, pannier, whatever yah call it.

    The air cleaner is (functionally) a traditional airbox - I just had to fabricate my own because the stock airbox would not fit any more due to the new rear chock mount. So I constructed a new one from fiberglass (using some left over basalt pipe wrap as reinforcing composite). It looks like I've never done fiberglass before and bought the wrong stuff, because that's exactly the case.

    The big ass pod filter is mounted onto a PVC pipe that is capped off, with the cap pieced by the original rubber "snorkle". The airbox volume is the same as the stock airbox so (in theory) the engine tuning remains very close to stock.

    Front wheel path is nearly vertical. TBH I don't know exactly what it is, I just have some software that I plug various dimensions into, and it spits out graphs that show how various important numbers (rake / trail / wheelbase) change as the wheel moves up and down. And important feature of the software is it also calculates brake dive effects based on wheel path and shock / linkage setup. It turns out that the "anti dive" created by such a linkage setup is highly variable depending on the spacing between the ball joints on the fork, so I can adjust (decrease) this effect by putting spacers under the lower ball joint. I recently removed all the spacers and recorded a video of suspension action and found I have about 20mm of brake dive under a max effort at front brake use. The video is pretty awful, but served its purpose.

    Last edited by sebwiers; 08-12-2017 at 04:51 AM.

  8. #8
    Here's an IMGUR album that shows the front end being assembled from bare frame to rolling stock, makes the linkages much easier to suss out.

    https://imgur.com/a/ZjsRr


    E
    DIT - fuckit, I'll link the more relevant pics.





    Last edited by sebwiers; 08-12-2017 at 03:13 AM.

  9. #9
    Bloke with the stick Gix11's Avatar
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    That is sheer shed built madness/experimentation done on a budget with a great amount of research and achievement - I take my hat off to you. My brain would not let me ride it based on the fact that it does not look strong enough for any kind of serious riding, but as I said, that's just my brain (a strange place). I would (on the other hand) be proud as punch if I could create such a beast and be confident in the knowledge that it was safe to ride. I have to thank you again for sharing and taking the time to explain in detail what you have done. Cheers.

  10. #10
    Quote Originally Posted by Gix11 View Post
    My brain would not let me ride it based on the fact that it does not look strong enough for any kind of serious riding, but as I said, that's just my brain (a strange place).
    I don't think you are alone in that, and doubt I'll ever find a willing test pilot / reviewer. Hell, I wouldn't ride it if I hadn't done the safety (static load) tests myself. It was pretty nerve wracking knowing that I might literally be ripping it apart, but better in the shop than on the road. The main component I was afraid of failure on was the rod end threaded into the fork crown pulling out - that's a 5/8" x 23tpi thread; the rod end is 4140 steel, but the hole its threaded into is 'just' 6061 aluminum. I also didn't have total faith in the rear monoshock setup, or TBH my welds (though a couple professional welders I know said they look decent enough, and there's ample joining area in all connections). The rest of the structure is ludicrously over built, I think. The fork legs are 1" x 0.11" wall steel tube, for example. I also spent a fair bit of coin on big, high quality bolts.

    I figured that threaded connection in the crown would have about 2.5 tons of force trying to pull it out under hard braking. The rod end is rated for 10 tons, but I could not find any good info on what the "pull out" force of my threads would likely be. So an actual load test was critical, because if that failed, I'd be in really sad shape.

    The tests were essentially a 2g braking force pushing backwards on the front axle (resulting in a 5 ton load on the threading I was concerned about), and a whopping 6g pushing upwards both the front and rear axles. These loads were intended to be double (for safety factor / fatigue tolerance) what could be encountered when riding in a non-crash situation. Part of the research was figuring out what those were (fortunately somebody posted to the mailing list, figures they took from an accelerometer mounted to the head stock of a street bike). As a sanity check, commercial taxi certification in NY City requires surviving a 2g force applied at a 45 degree angle rear/up to the front axles (similar to running hard into a pothole or speed bump).

    Here's a pics from testing.



    The wood around the fork in that picture is only there to stop the fork from rotating - I didn't have the steering (or brake tabs) fabbed at that point, because if it failed testing, why waste the work? There's also some metal that look like bracing, but is in fact providing mounts for dial indicators so I could measure how much the fork moved relative to the motorcycle frame, and relative to the test stand. Since movement relative to the test stand was nearly tripple what movement relative to the frame was, I think the vast majority of the flex was in the frame, not the components I built. That's not surprising given the frame design, but was good to confirm.



    This is the rig for applying bump loads to the front. It also allowed me to directly measure wheel force vs travel (which I also did at the back end). Not that I knew if the numbers I got were bad or not...



    Front end at max test vertical load.





    Rear end at max test vertical load.
    Last edited by sebwiers; 11-12-2017 at 11:57 AM.

  11. #11
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    Id ride that. cool bike man
    Do these ideals make my arse look fat?

  12. #12
    ASF Gold Full Member
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    WELcome and much cool, love the testing.
    I am very proud of my race....the fucking human race...........

  13. #13
    Bloke with the stick Gix11's Avatar
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    Yes, the testing is as interesting as the actual build. Thanks again mate, great stuff.

  14. #14
    ASF Gold Full Member LKC73's Avatar
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    Wow that is such a great build thread! The work you have put into it is nothing short of amazing.
    Street Monster GSXR 7/11 water heater!
    Project R1 underway, The "Raven"

  15. #15
    ASF Premium Full Member JimZXR's Avatar
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    Don’t think your engineering skills can be faulted mate; top job.

  16. #16

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