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Ranger's 2016 xs650 chopoff build

Discussion in 'The Garage' started by Ranger, Dec 16, 2015.

  1. Ranger

    Ranger XS650 Addict


    Getting parts together for my build for the 2016 xs650 Chopoff and Show at Pandemonium Custom Choppers in Ohio. I didn't intend to enter the chopoff again, but my boy had such a great time last year, I decided to build something 2-up so he could ride with me.

    THE PLAN: To build a 2-up chopper with about 4 inches of stretch in the rear, and either a de-raked or factory raked neck (I'm thinking 29-32 degrees). I'll be using 8 over 34mm tubes, and I'm going 8 up, 0 out on the neck.... Did I mention I'll be building my first full frame?

    I've got 2 36 spoke hubs. I'll be lacing up a 21 in the front, and an 18 in the rear.

    And I'm thinking I'll build my own coffin-style tank.
  2. figure8

    figure8 XS650 Guru

    I already know this will be awesome, subscribing now.
  3. Ranger

    Ranger XS650 Addict

    Thanks buddy, I hope so... I hope I'm not over-extending myself. I saw you got your exhaust lined out. Looks good!
  4. figure8

    figure8 XS650 Guru

  5. Ranger

    Ranger XS650 Addict

    Here's a picture of the inspiration for the build... at least for the stance. This kz650 was built by Ryan Boehmer out of Iowa. High neck, extended forks.


    I was planning to achieve this look by using some extended fork tubs my brother has laying around... but then I visited by buddy David at Voodoo Vintage on Monday and saw his Relic girder prototype in person. Soooo I'm leaning toward using one of those...

    Here's my oldest, Eli, with the girder... Eli is the reason I'm entering the chopoff again. I was going to go anyway, but I'm going to build something we can ride 2-up on.

  6. That girder is bad ass. Saw it on instagram a while back.
  7. Ranger

    Ranger XS650 Addict

    Yeah, David does great work... and I'm a sucker for a girder...
  8. Ranger

    Ranger XS650 Addict

    I'm still gathering parts, but I've done a couple of small things for the bike.

    The main component for my charging system arrived a couple of weeks ago:


    I know it's been done, but hopefully I can bring something new to the table. Ever since my buddy David at Voodoo Vintage did one on a cb750, I've wanted to do the alternator conversion. I've got my plan figured out, and I'll know in a couple days whether it's going to work.

    I should also mention, that I'm just doing this "because" ... it would cost less and make more sense to go with a HHB PMA, because my plan involves a new sidecover, hydraulic clutch conversion and 1 to 2 intake.

    But for the other folks that don't have a lick of sense (like me) I'll document how I do it.

    One of the other components I needed was the keyed rotor hub that presses onto the crankshaft, so I disassembled a rotor I had laying around:


    It's just a press fit. I didn't really need to remove the contact plate to press the hub out, but I like to take things apart. On the contact plate, there are 6 circles made of epoxy. If you chip the epoxy out, there's machine screws underneath. If you wanted to rewind your rotor, this is how you'd disassemble it.
  9. Ranger

    Ranger XS650 Addict

    Another point to mention: because of the direction of the engine rotation on the xs650, the built-in cooling fan in the alternator will be turning in the wrong direction. It will charge either way, but it won't self-cool. I don't think this will be much of an issue, but I just thought I'd point it out.
  10. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi Ranger,
    "everything takes longer and costs more" how many build hours are available between now and the show?
    How about you make the coffin tank as a structural item so it acts as the frame's top tube?
    I'd say 12ga to be a structural item? And that thickness welds up easier than the usual 22ga gas tank material.
    You can also make it big enough to hide all the electrics rather than using the same old fake oil tank for that purpose.
  11. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi Ranger,
    you plan to direct-drive the alternator by removing it's pulley and plugging it into the crankshaft's end?
    How about belt-driving it instead so it turns t'other way and the fan works?
    Pulley on the engine crank, alternator up front like on my old Velocette?
  12. Ranger

    Ranger XS650 Addict

    I've got until August, so in theory I have the time... money might be a bit of an obstacle, but I think I can overcome it :thumbsup:

    That would definitely be pretty cool, but I've got a couple ideas for the tank/frame already... I agree with you on the fake oil tank. I've got a few ideas in that regard...

    I'll be using a pulley/belt. I'm going to mock up the alternator in front of the motor, adjacent to the crankshaft (the spot that make most sense, but will be pretty ugly in my opinion). I'm also going to mock it up behind the cylinders, which I think will look much better, but likely will force me to go to a single carb setup. I like the simplicity of a single carb in theory, but Hugh says dual carbs are better for tuning for performance.

    Either way, I'm not dead set on any certain method. If my current ideas don't work, I'll remain rigidly flexible.
  13. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi Ranger, well, January is just about over and she'd better be ready by the end of July
    so that's only 6 month's-worth of weekends and evenings.
    OK, I guessed wrong about the planned alternator mount.
    Looking at the pulley end, which way round should the alternator turn for the fan to work?
    If it's clockwise and the engine turns counterclockwise mebbe up front will work better because it's out in the airstream?
    I reckon it ain't the single carb that's the problem, it's the assymetric manifold.
    But you are scratch-building the bike's frame.
    You don't HAVE to have a center frame tube that's right in the way of using a straight back single carb manifold.
    And rigidly flexible? ain't that a fair description of a hardtail with a wobbly seat?
  14. Ranger

    Ranger XS650 Addict


    Yeah, I just don't like it up front... I'm hoping that with less load on it than it would have with a car, it will be fine. I've also thought about taking the alternator apart to see if I can somehow flip the fan, but I don't know that I'll do that either.

    Yup, that's the plan.

  15. Ranger

    Ranger XS650 Addict

    I spent some time at my buddy's gasket manufacturing company yesterday working on my sidecover/alternator bracket design. We did several tests out of 1/8th mdf, with the final mockup piece being milled out of 3/8th high-density plastic. Here's what I ended up with:


    I'm thinking I'll be changing the cradle a little bit, so that the two ears of the alternator are more perpendicular to the rotor shaft.

    In the mockup, I've spaced the alternator far enough out that the belt will clear the Aprilia slave cylinder for my hydraulic clutch. I'll need to figure out the length i need for the clutch rod, and have a new one ground.

    I also need to figure out what I'm doing for a drive ratio for the alternator, so I can make my pulley assembly for the crankshaft... (see next post)
  16. Ranger

    Ranger XS650 Addict

    So I'm pretty weak on 2 things when it comes to bikes... electrical and carbs.

    I need to figure out if I should purchase a different alternator, and what my drive ratio needs to be for my pulleys. For aesthetics, I'd love to go to a 1:1 ratio, but I'm thinking a minimum of 2:1 might be necessary so the alternator will charge properly.

    Below is the spec sheet that came with the alternator I purchased. It's a cheap ebay 1-wire, 35 AMP unit.


    I got the 1-wire alternator for it's simplicity, but didn't realize that you need to reach a certain RPM for the alternator to turn on. Once it's on, it will remain charging until the bike shuts off again. A 3-wire alternator will begin charging as soon as the bike starts.

    According to the sheet, this particular alternator turns on at 1490 RPM.

    From what I've read, the ideal idle for an xs650 is about 1200 RPM. If I go with a 2:1 pulley ratio, assuming I'm idling at 1200 RPM, the output would be 27 AMPS. (according to the sheet)

    Is that good?

    They do make a 70 AMP 3-wire alternator that is the same size as the one I bought. I can't find a spec sheet like the one that came in the box, but if it's always charging, and has a higher output, it would stand to reason I might be able to go with the 1:1 ratio (which again, is purely for aesthetics).

    I welcome help, opinions, debate... keeping in mind that I'm just doing this because I want to, not because it makes sense :D
  17. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Okay, this could be fun.

    My 71 only puts out 8 amps. That's more than it needs. A 35 amp alternator on my bike would be like having a 8000 gallon aquarium for a goldfish. Plenty of room, and not much gets used.

    That alternator probably uses the old-style Delco design self-powered armature system, powered by an internal diode-trio, and needs a minimum rpm to achieve reliable output. If so, there may be a way to boot-strap the charging output, so it puts out at a lower rpm. Need to find an old-school wrench out there who's really familiar with old Delco-Remy alternators, to see if that could be done to yours

    Otherwise, consider keeping your drive ratio as low as possible, say 1500 at the alternator with 1200 at the engine.

    Unless your bike will be equipped with a portable welder and 400 watt surround sound...

    Edit: FYI, flipping the cooling fanblade over won't change air direction. You'd need to pound the thing into submission, making the blades point in the opposite direction...
  18. rockhead

    rockhead XS650 Enthusiast

    That's a great set up. For a supercharger. Throw away the alternator ......
  19. Ranger

    Ranger XS650 Addict

    Thanks for the insight 2M... Now that I think about it, there used to be an alternator/starter shop a couple towns over. If they're still in business, that might be who I need to talk to.
  20. Ranger

    Ranger XS650 Addict

    Ha! Once, I get the design finalized, I'll send you the CAD file... That's all you buddy!

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