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Thread: Black cherry

  1. #1
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    Black cherry

    Welcome to my build thread for-
    BLACK CHERRY

    Apart from a few critical jobs that require professional machines.
    All design, fabrication and build is my own work.
    My ideas revolve around a few rules.
    Use as much of the original as possible.
    Finesse PMWs ideas.
    Keep it quiet.

    This Chassis started life as an early GSR25 with no provision for a rear brake.
    It has a small kick out at the back and shorter total length.
    I purchased this off eBay..
    The guy selling it was insistent that the only time I could pick it up was 9pm due to work..
    I should of smelt a rat, because when I picked it up it was pitch black.
    He said there was no way I could start it because it was so noisy.
    Sadly when I got it home it was littered with major problems.
    Two teeth missing of the pinion.
    Brake pads were missing.
    Chain was so badly stretched you could wind it round the pinion.
    The end was missing off the throttle cable.
    ETC ETC ETC ETC ETC….

    That was then….. This is now…….
    The main frame is modified with 3 inches added to the middle to help with high speed stability, and to make it feel less cramped.
    A stepped tube was lathed up, the ends slide in to the original chassis tube, with the centre being the same diameter as the external chassis tube
    I did contemplate giving the head stock 1 degree more tilt for stability..
    But it would of moved the handle bars back another 2 inches.
    The deck mounts were removed, corners welded and repositioned .
    Y fork rear using a big foot rear end with half of it cut and spun thru 180 degrees to aid in a smooth transition where it meets the original chassis.
    Axle tubes cut down to allow the axle assembly to be removed as a one piece cartridge unit for servicing.
    A bespoke hand fabricated IS brake mount.
    The Fuel tank mounts are welded to the chassis, once the tank is mounted the brake caliper sits in the pocket at the back of the tank.
    Exhaust hole welded up.
    A small additional strengthening plate at the front of the engine mounting bracket.

    Paint…
    After all the modifications were done, the chassis was blasted with a fine garnet powder.
    An acid etch aerosol went on first.
    Then a pro laid down a coat of high build primer.
    Two cans of BLMC BLACK CHERRY MICA paint.
    Then three coats of two pack lacquer, once again a pro stepped in.
    Annoyingly in the photos the finish looks awful, but trust me its fab.
    It is seriously black until the sun strikes it..
    When it pops with a red black lustre…
    Bite a black cherry in two, it looks like that.
    On to the photos..
    J.
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    There is nothing that cannot be fixed with a good cup of Tea.

  2. #2
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    More photos....
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    There is nothing that cannot be fixed with a good cup of Tea.

  3. #3
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    Hi.
    Weeeeeeeeeeeeeeee

  4. #4
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    More photos of the chassis before paint....
    figuring out which bit goes where.
    J.
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    There is nothing that cannot be fixed with a good cup of Tea.

  5. #5
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    VERY nice so far! I really like the extended frame and having the rear brake on the other side of the wheel and away from messy chain lube.
    CP......
    HOW we ride today, may determine IF we can ride tomorrow

  6. #6
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    Yea I love the rear tab on the other side.. I am doing the same on my next msjor build..


    Nice start here sir

  7. #7
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    Hi SJ.. Thanks for the comments.
    The original idea for the Y frame was a single sided front fork..
    The GSR25 had the threads on the top of the forks worn away because the post fitting was too high and the headset was run loose..
    So the fork was scrap, so I thought I may as well use it for the rear and put a brake on it...
    That was until I saw a Bigfoot frame for sale on Ebay..
    It inspired me to re-design the rear to use the BF frame...
    I felt a rear brake is essential on a Goped..
    After a few interesting moments on the TSi on wet surfaces..
    The rear brake allows you to add a little drag control to stop the front wiping out.
    J.
    There is nothing that cannot be fixed with a good cup of Tea.

  8. #8
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    Forgot to say....
    This is the early (late) frame, so there is no room to fit a brake disc in like the GSR40 has..
    The sprocket runs about 4mm away from the chassis tube..
    I was just looking at the PRO60 frame..
    It appears that the 25 frames main tube is identical in form to the PRO60..
    But the 60 has thick wall on the head stock, down tube strengthener tube etc etc..
    J.
    There is nothing that cannot be fixed with a good cup of Tea.

  9. #9
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    looks pretty ****in good to me!!!

  10. #10
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    niz is offline Suck, Squeeze, Bang, Blow
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    Great fab work, look forward to seeing this come together .
    Quote Originally Posted by Pushinit View Post
    There's a list? Wow that means Arick dodge was first and NIZ was second. Good to know.

  11. #11
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    FORKS.........
    The Forks are actually 2 single sided forks joined together.
    One had a stripped thread, so I Name:  DSCF1067.jpg
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Size:  106.5 KBsliced it up and mounted it to the good BF fork that came with the donor BF frame
    The IS brake mount is hand fabricated.
    As you can see, the gap between the axle tubes is wider than normal but the overall width of the forks is narrower than the Bothy forks.
    The extra width in between the insides of the legs is for the
    ShackTune Third bearing brake disc adaptor (more on this later).
    The axle tubes were refaced straight with a piloted broach I made.
    The new forks are on the left in photos.
    J.
    There is nothing that cannot be fixed with a good cup of Tea.

  12. #12
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    It always amazed me that a chain tensioner was necessary.
    Very few motor bikes have them..
    Two things that lets the Goped chain system down first is the fact that the chain is so short it cannot absorb any inconsistencies.
    The second and main problem is the way the rear sprocket mounts on the posts.
    Even the slightest movement when tightening the bolts up and it runs up and down.
    So the chain goes slack tight slack tight etc..

    I decided to stop the problem of the sprocket moving rather than remedy the consequences..
    The first photo shows the original prototype..
    It was merely to prove the concept, and I could make it on my lathe at home..
    The original idea was to shorten the sprocket posts/tubes and add this between the posts and sprocket..
    The second photo shows the 2nd prototype..
    I soon realised that it would make more sense to incorporate a way of
    mounting a modern IS brake disc.
    Then both the brake disc and sprocket could be kept central to the axle and thus would run a correct radius around it.
    One problem with the second prototype was it would be impossible to inflate the tyre on the BLACK CHERRY with a sprocket one side and the brake disc on the other..
    The third photo shows the final CNC product from the CAD drawings.
    It addresses all the problems I could see..
    On the GSR40s/GTR it can be used instead of the original disc and posts.
    On GSRs with no rear brake it can be used on the other side of the sprocket, by lathing 4mm off the spacer posts/tubes.
    On hybrid Y frames like BLACK CHERRY it can be used on both sides for a 4 bearing axle.
    It can also be used on the front too but you will have to cut the tube down on the fork.. Also I think it would only be
    advisable on a Bothy type fork and not single sided.

    If anybody wants the CAD drawings let me know.
    I have also calculated the change in spacers at the rear on the GSR & GTR
    The early 40 frame has 2 spacers and the later Maddog frame has one because the frame has a longer tube sticking out.
    The bearing is the same as the wheel bearing but thinner and more widely available.. You can use a wheel bearing though.
    The dimensions internally for the bearing, allow it to be a tight slip fit.
    J.
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    There is nothing that cannot be fixed with a good cup of Tea.

  13. #13
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    Quote Originally Posted by MrTea View Post
    It always amazed me that a chain tensioner was necessary.
    Very few motor bikes have them..
    Two things that lets the Goped chain system down first is the fact that the chain is so short it cannot absorb any inconsistencies.
    The second and main problem is the way the rear sprocket mounts on the posts.
    Even the slightest movement when tightening the bolts up and it runs up and down.
    So the chain goes slack tight slack tight etc..

    I decided to stop the problem of the sprocket moving rather than remedy the consequences..
    The first photo shows the original prototype..
    It was merely to prove the concept, and I could make it on my lathe at home..
    The original idea was to shorten the sprocket posts/tubes and add this between the posts and sprocket..
    The second photo shows the 2nd prototype..
    I soon realised that it would make more sense to incorporate a way of
    mounting a modern IS brake disc.
    Then both the brake disc and sprocket could be kept central to the axle and thus would run a correct radius around it.
    One problem with the second prototype was it would be impossible to inflate the tyre on the BLACK CHERRY with a sprocket one side and the brake disc on the other..
    The third photo shows the final CNC product from the CAD drawings.
    It addresses all the problems I could see..
    On the GSR40s/GTR it can be used instead of the original disc and posts.
    On GSRs with no rear brake it can be used on the other side of the sprocket, by lathing 4mm off the spacer posts/tubes.
    On hybrid Y frames like BLACK CHERRY it can be used on both sides for a 4 bearing axle.
    It can also be used on the front too but you will have to cut the tube down on the fork.. Also I think it would only be
    advisable on a Bothy type fork and not single sided.

    If anybody wants the CAD drawings let me know.
    I have also calculated the change in spacers at the rear on the GSR & GTR
    The early 40 frame has 2 spacers and the later Maddog frame has one because the frame has a longer tube sticking out.
    The bearing is the same as the wheel bearing but thinner and more widely available.. You can use a wheel bearing though.
    The dimensions internally for the bearing, allow it to be a tight slip fit.
    J.
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    There is a tool for what you are describing . I forget qho makes it . Also there is the skopod quick change hub
    PEDFEST 2013 ALUMNUS
    PEDFEST 2014 ALUMNUS
    PEDFEST 2015 ALUMNUS

  14. #14
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    Thanks for the info Greenborroco..
    The idea of the system is to take away the problem altogether, that way no tool is ever going to be needed.
    When I started my design I was not aware that the Skopod adaptors existed.
    It was only natural that they would end up looking similar..
    Non of the dimensions can be altered, hole size, hole PCD, hole quantity, thickness etc etc etc.
    The skopod adaptors don't resolve the sprocket problem as far as i'm aware.

    There is one big issue that will keep cropping up while I post on here..........
    Because I live in the UK.... all most all the parts for gopeds are not easily available..
    Any item I buy for $30 (£20) will cost at least double by the time it arrives from the US.
    And I would rather do it my own way.. Its all about the build and the journey for me..
    J.
    There is nothing that cannot be fixed with a good cup of Tea.

  15. #15
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    Todays offering………..
    Because the chassis was cut and shut with 3” added to the length..
    The original deck was not going to work.
    I picked up a ½ sheet of Russian Birch ply about 15 years ago.
    It is 11 ply with a nicely marbled face veneer.

    The whole board was moved out of the wood store and in to the house for 5 months to allow the ply to settle in to being indoors (which is where it will live when finished).
    Once the moisture level had dropped to a low level.
    Its out with the wood working tools.

    Before cutting I decided to integrate a few different ideas from various
    Goped decks.
    Width dimension was from a GSR40
    The squarer front shape comes from the late GSRs
    The rear has both points equal lengths
    Once I had decided on the design,
    Cut with a jigsaw, then sanded the edge to finesse the shape and leave a nice smooth finish for the router bearing to roll on.
    Because the board is a few mm thicker than an original deck, I used 2 different radius cutters on the edge.
    The upper edge cut used a small tight cutter.
    With the lower edge being cut with a larger radius.
    The larger lower radius gives the impression that the board is thinner than it actually is.

    The board was then hand sanded, vacuumed clean then a light coat of aerosol lacquer to seal the surface..
    The surface was then knocked back with a fine glass paper.
    Another light coat of can lacquer, then knocked back.
    This first stage is just to seal the surface.
    The deck was then left for 4 weeks to settle and all the thinners to evaporate.
    This stage is essential to completely seal the surface, because it will be baked at later stage and air bubbles get forced out of the wood grain.
    The board was then sprayed by a pro with 2 pack automotive lacquer.
    3 coats in all, and baked at 60 Centigrade for 40 minutes.
    Left for 2 days to fully cure, it is then knocked back with 1200 disc on a random orbit sander (ROS)..
    It is then hit with another 3 coats of lacquer.
    Knock back.
    Lacquer..
    15 coats in all… it is allowed to rest for a week, then 1200 grit and then on to 3000 Trizact disc.
    Then a final wet 3000 Trizact by hand..
    Once again allowed to rest for week, before the final cream cuts by hand..
    The final photo has the reflection of some forks on the upper edge......
    J.
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    There is nothing that cannot be fixed with a good cup of Tea.

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