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Project Alan's CB250 Nighthawk

Discussion in 'Your 250cc Projects' started by Alan f., Jul 18, 2018.

  1. Alan f.

    Alan f. US Spec CB250 Nighthawk 1993

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    Thank you for the kind words Gents, I've got a great deal of lost momentum to make up for on this one.
     
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  2. Alan f.

    Alan f. US Spec CB250 Nighthawk 1993

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    I don't know if this is a cafe or a bobber or any of the trendy classes. I guess we'll take a vote when its done.
     
  3. TonyZXR

    TonyZXR Well-Known Member

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    nice one! , this is gonna be sweet when it's finished
     
  4. Alan f.

    Alan f. US Spec CB250 Nighthawk 1993

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    I'm using the original swingarm, frame, tank and engine so people might recognize what kind of bike it was.
     
  5. Andych

    Andych Senior Member Premium Member

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    I dont think it is really either a bobber or a Cafe, more just a Custom build. Whatever it is... it is looking pretty sweet so far :)
     
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  6. Alan f.

    Alan f. US Spec CB250 Nighthawk 1993

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    Thanks Gents, I've been struggling with a few tail designs that'll work with that fender, case and a stock seat.
    Right now I'm in the middle of putting a bending brake together from bits I already have so I can bend up the tail section (also functioning as a rack for the case) from some 3mm alloy plate I had lying around. I'd experimented with different bending techniques, scoring with a cold chisel, drilling holes at different spacing along the bend line, soap and heat, and a few others but a small radius bend with a brake will be best. I'll post it in the handmade tools section when its done. Wish me luck.
     
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  7. Alan f.

    Alan f. US Spec CB250 Nighthawk 1993

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    My little bending brake still has some more hours to go, I've been working at it here and there when possible but nothing to show off just yet.

    But I'd like to show off this bit, I've always thought a big tank on a small bike with a comfortable seat and some type of fairing would really be fun for long rides. My previous Honda CM400C was ok for the first two hours, then the seat and fuel capacity would show their limits.

    I spotted this Kawasaki ZG1000 or GTR1000 tank on eBay for a good price, clean inside and out, good factory paint and some little dents I can live with.
    After a little research I found a Corbin seat from a GPZ900 (top gun movie bike) will mate up to the tank acceptably and is much shorter than a ZG or GTR seat.

    I'm not sure if I'll use them on this project but what do you think? I conservatively estimate a range of 500-750 miles.

    L0nmZn.jpg

    1oaQbG.jpg

    czxIvV.jpg
     

    Attached Files:

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  8. Murdo

    Murdo The Good Doctor Staff Member Premium Member Ride and Events Crew Contributing Member

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    That looks sweet, not a lot different to the original tank only bigger. Will you have to modify the steering stops so the forks can clear the bigger tank. Corbin have a good name here for comfy seats, and you can cut it down to suit the rear case.
     
  9. Alan f.

    Alan f. US Spec CB250 Nighthawk 1993

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    I haven't figured out the steering stops yet, but my first priority is to use the stock tank. Unfortunately I noticed a failed lining in the stock tank so I'll have to fish out a piece of it to determine what it'll dissolve in. Not a very encouraging find.
     
  10. Alan f.

    Alan f. US Spec CB250 Nighthawk 1993

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    Thank you Murdo!
     
  11. Alan f.

    Alan f. US Spec CB250 Nighthawk 1993

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    As its winter up here I've been trying to motivate myself to get back to work on this project. I have been spending what time I can in the workshop but it hasn't been very often and I haven't made much progress.
    What I got stuck on was some 3mm aluminium plate that I'm planning to bend into a rear rack and some side covers.

    The stuff is pretty tough to bend and after weighing my options I decided that I'd be building a bending brake of some sort. I'm working in a basement workshop and welding is just not an option, so my little Sieg X1 was going to be doing most of the work. This is what I came up with using mainly scrap that I'd brought home from work over a decade ago. The hinges, bolts and some screws are the only items purchased, less than $10 US.

    [​IMG]
    The clamping plate is held tight by two bolts that thread in upwards through the bench top, it's a little awkward but couldn't get any simpler.
    [​IMG]
    The hinges are mortised and the clamping plate has been milled about .75mm deep except for 3mm on the front and back edges.
    [​IMG]

    I don't plan on bending stock this thick very often, but it's nice to know that can when i need to.

    Test pieces:
    [​IMG]
     
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  12. Murdo

    Murdo The Good Doctor Staff Member Premium Member Ride and Events Crew Contributing Member

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    If it works then all good. Doesn't matter what it looks like.
     
  13. Alan f.

    Alan f. US Spec CB250 Nighthawk 1993

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    Thanks Andy and Murdo, I like that it'll store easily when I'm not using it.

    Hopefully I can get past this bodywork soon. What do you think of polished bodywork mixed with painted tanks?
     
  14. Murdo

    Murdo The Good Doctor Staff Member Premium Member Ride and Events Crew Contributing Member

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    If done right should look good.
     
  15. Stubanger

    Stubanger Well-Known Member Premium Member

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    A heat gun will help with the 3mm ally
     
  16. Alan f.

    Alan f. US Spec CB250 Nighthawk 1993

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    Finally an update!
    I had a 750mm square sheet of 3mm alloy plate from which I fashioned (by use of Cardboard-Aided-Design) what I'd envisioned as frame hugging bodywork fading to the rear into a rear rack with a small top case.

    Well today I broke out the bandsaw and trimmed off all the extra bits and broke out the bending brake. It worked fairly well considering the two bends I made were 200mm long of 3mm alloy plate.

    After lots of time at the drill press with a rotary file it fits, not well but it fits. I'll be whittling it down in the days to come until I'm happy with it.

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
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  17. CB250 Scrambler

    CB250 Scrambler Member

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    Looking great, well done
     
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  18. Alan f.

    Alan f. US Spec CB250 Nighthawk 1993

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    Thanks Scrambler!

    Long overdue update, I've got valve clearances set and reset, clutch checked, scuffed and reassembled and oil pump checked and reassembled. I've just built a nice little stand for my polisher and I'll be polishing some engine covers outside on sunny days in the weeks to come. Rear fender has been cleaned and sanded in preperation for black appliance epoxy when I paint the frame later on.

    Today I did some final trimming and adjusting on the aluminum rear bodywork, apart from some edge sanding and a couple of mounting holes it's ready for polishing.

    Pics:

    s1.jpg s2.jpg s3.jpg


    And I'll probably put some indicators to compliment the integrated tail light here

    s4.jpg
     
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  19. Alan f.

    Alan f. US Spec CB250 Nighthawk 1993

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    Please moderators, delete the repeated posts. I realize I'm geographically distant but when I receive errors generally I'll refresh the page and try again.
    Sorry for the inconvenience.
     
  20. CB250 Scrambler

    CB250 Scrambler Member

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    That looks fantastic, that rearguard set up is the bomb. I might have to do something similar.
     

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