The building of my vintage racer

Discussion in 'Airheads' started by FreeTheBeast, Apr 24, 2012.

  1. FreeTheBeast

    FreeTheBeast Shunpiker

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    So, let's go straight to the finished product...

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    This bike will be my racing bike in the USCRA race series. Its chassis is a 1970 BMW R75 /5. It has a 750 motor assembled from different sources of used parts.

    But all of this began with Marcus -

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    I met Marcus while racing in hill climb races in Vermont. He has been building bikes and competing in vintage racing for a number of years. As you can see, Marcus is an interesting individual. Anyway, in 2011 I went to a few of the races at New Hampshire Motor Speedway and thought it looked like a lot of fun. Over the Winter, I bought the most part of a bike from Marcus.

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    The motor came without pistons or cylinders...wire harness...ignition system...etc.

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    I needed to get a lot of things to get the thing together. I brought it over to my friends at MAX BMW. I was able to get all of the used parts that I needed. The motor was assembled at MAX and the gearbox was tuned up.

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    I took care of the frame. I coated it using POR15 Bare Metal. It is supposed to look like naked metal. I think it looks okay for a vintage racer.

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    The frame went back to MAX BMW and it was put together.

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    I put Avon race rubber on it. I ordered a custom top brace from ToasterTan.

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    I'm using a Shorai battery. I have mounted it under the seat cowling.

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    I enlisted the help of my buddy, Pat (Adv: Mudhen), to weld on a piece of angle iron as a base for the steering damper.

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    I think this catch bottle will certainly make the bike go faster...

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    The belly pan is a custom piece of work by another friend, Mike (Adv: 280racer), who will also be racing with me.

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    So, the bike is done. All safety wiring is complete. The thing runs and sounds pretty good. New racing leathers should be ready any day now. I'm looking forward to it. The first races are in early May. This year is all about getting out on track and learning what's going on. The 32mm Bings aren't going to light up this bike, but I should certainly get around the track.

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    Rear sets: Boxer Metal
    Seat and starter cover: BoxerCafe.com
    Top brace: ToasterTan
    #1
  2. 2twisted

    2twisted GoodNYou

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    Nice job. :clap
    #2
  3. Voltaire

    Voltaire Bored Of The Rings

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    Nice work, you sure will have fun as I have recently completed a similar project.
    The shorai battery...are you running total loss? would it last a whole weekend...say 10 starts and an hour or so of running? whats the model of it. Cheers John
    Oh and the starter/air cleaner cover looks really smooth, did you make it?
    #3
  4. FreeTheBeast

    FreeTheBeast Shunpiker

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    I am going total loss. I hope the battery does well. I do plan on recharging with a generator in between races.

    It's a Shorai LFX36L3-BS12.

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    #4
  5. mykill

    mykill odd

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    Nice!
    #5
  6. Boxer Metal

    Boxer Metal Mad Scientist

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    Very nice.
    #6
  7. Renner

    Renner rockin' the toaster

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    :lurk

    can you post a video clip so we can hear it run? :ear
    #7
  8. hardwaregrrl

    hardwaregrrl ignore list

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    Very pretty!!!:clap:clap:clap
    #8
  9. FreeTheBeast

    FreeTheBeast Shunpiker

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    Here's an iPhone video of Marcus giving the bike a quick spin.

    <iframe width="420" height="315" src="http://www.youtube.com/embed/H5WUGG9lxOQ" frameborder="0" allowfullscreen></iframe>


    <iframe width="420" height="315" src="http://www.youtube.com/embed/Tyw-Pkzal08" frameborder="0" allowfullscreen></iframe>
    #9
  10. apt13

    apt13 Been here awhile

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    awesome bike! but the dreaded portrait style video. turn your phone sideways when making videos! haha.
    #10
  11. rambozo

    rambozo Been here awhile

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    sounds and looks very nice, lotta nice mods

    por looks good on the frame
    #11
  12. FreeTheBeast

    FreeTheBeast Shunpiker

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    [​IMG]
    #12
  13. Renner

    Renner rockin' the toaster

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    very cool, thanks for the vids :nod
    #13
  14. pommie john

    pommie john Long timer

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    Very nice work.

    The only comment I'd make is that I've never been a fan of putting the battery up under the seat hump. It's a lot of weight high on the bike and it's a long way from the starter motor. That's a long hot wire to the starter which will cause voltage drop. Whether that's a practical issue or not is debatable. I put mine on top of the gearbox, nice and low, and near the starter.
    #14
  15. FreeTheBeast

    FreeTheBeast Shunpiker

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    Yes, your points are valid. Here are my counterpoints... The battery is a Shorai. It is lithium iron - very light at about 5 pounds. It is not the typical lead acid battery we used to know. Also, I am using a custom wire to the starter. It is very heavy gauge and has gold plated (really!) terminal ends. It fires up pretty well. I may also put another battery in tandem for starting when cold - as well as using starter fluid first thing. We'll see how it goes, but I understand your points. I was initially planning to put the battery in the belly pan, but under seat was considerably easier.

    Thanks for your input. I appreciate the feedback.

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    Battery to starter motor cable is from here:http://www.howardshorns.com/cables.htm
    #15
  16. pommie john

    pommie john Long timer

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    Nice light battery.

    Gold plated cable ends? Extra weight :evil
    #16
  17. supershaft

    supershaft because I can

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    I have made the same comment about the battery on a number of cafe build threads. It is just all wrong to me in theory and practice. 5lbs? That's damn near a gallon of gas that never goes away. IMO THE secret to tuning success is the same as improving riding skills: all the little stuff adds up! Underneath the tranny/engine? We have all been through this before via Honda GP bikes. Weight can be too low as well as too high on two wheelers. You want to try to center weight around the bike's pitch axis which I suspect is somewhere about where the starter is (that's with the bike AND rider!). I would put the battery above the tranny or maybe even Ducati style and mount it on the side above the left cylinder. Easy to get to which is always a plus with constant loss systems. The weight is closer to the pitch axis and further forward which I think the bikes in general could use, not to the rear! Also on the left to compensate for the engine favoring the right as well as the weight of the drive shaft and final drive.

    I think you done good putting a 18" wheel on front. I run Avon race rubber too and I suspect that my setup favors the AM18 90/90 over the AM22 110/80. It's a shame because the AM22 cups a lot less and wears better but I think just the bit bigger tire gets me some chatter that I don't get with the 90/90. Just something to maybe try. You'll be going through the tires quick enough to try the difference soon I hope!

    I forgot to ask: do people run constant loss AND starters? It sounds like trouble to me but I have no experience with that combo.
    #17
  18. pommie john

    pommie john Long timer

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    Yes I do. I have a Yuasa 12 amp hour battery and it lasts all weekend, but I usually put it on charge on the Saturday night just to be sure.

    I did have a couple of occasions where the battery started to fail, but when it won't turn the starter it still has enough charge to run a race if you can push start it. So it gives you a warning when it's time to put it on charge :D
    #18
  19. supershaft

    supershaft because I can

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    Great! Sometimes I think a starter would be worth the weight! There's nothing like showing up to the starting grid late and huffing puffing dog ass tired because you couldn't get your bike started. It's NOT the path to good starts!
    #19
  20. pommie john

    pommie john Long timer

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    You know that feeling on the dummy grid when there's been a crash in the previous race and they keep you waiting, and you're not sure whether to stop the motor to avoid it overheating, but you're worried it will be hard to push start if you do, and you know as soon as you stop the motor, they'll wave you out onto the track?
    You know that feeling?
    That's what starter motors are for :evil
    #20