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Yamaha RD125

Posted on October 13, 2012 by Scott in Café Racer, Racer. 15 comments

By guest writer Ian Lee.

Full length fairings. Small capacity engines. Pizza cutter tyres. All strike up images of 1970s motorcycle racing, but do these statements make you think of a fully registered streetbike? Bobby Costello, of Costello Fabrications, has done the ton in creativity and engineering to bring this build as close as possible to a full race bike, yet still be able to blast around town when the desire arises.

Bobby is an allround bike builder/fabricator/welder/mechanic specialist. By day he works at Motoretta Atlanta, a Vespa dealership that also works on vintage motorcycles and mopeds. In his spare time he helps out 1977 mopeds, and Team Indigen, building the ‘ripping’ motor in Indigen’s Diablo motorbike. Bobby also finds time to run Costello Fabrications, a fabrication workshop that will build anything from exhaust headers through to bike frames to furniture.

Let’s hear Bobby tell us of his initial contact with the bike: ‘well it started out as a pretty nasty RD125 I purchased from the Barber swapmeet for 200 dollars, I had to drag it the half a mile back to my parking spot with a locked rear wheel’. After getting it back to the shop it was stripped back, the frame shaved of any superfluous brackets. Bobby then welded in trellis rearsets, and a high rear loop onto the frame.

The substance of this bike is equal to it’s form, with a decent amount of though and effort going into the mechanics of the bikes. A Yamaha 80 tank has had a dummy section added to it, to hide the electronic components of the bike. Braking at the front has been uprated by fitting an RD350 brake drum, the rear staying standard, both rims being supplied by Excel. Front end stability has been helped by fitting a clamping top tree, with adjustable top plates to the fork.

As for the engine, Bobby was rather lucky with his $200 purchase. An initial oil drain showed no worrying signs, and after a good check over, it was decided to clean and mod the transfer, to fit 28mm Mikunis. The exhaust is made up of newly built exhaust headers, 3 midcones from some moped expansion chambers, and rebuildable silencer sections.

Keeping with the ‘less is more’ idea, as well as the ‘allround bike builder’ motif, Bobby himself moulded up the badges, seat pan, front and rear fender out of carbon fibre. Having a full ‘taylor-style’ race fender, with delete headlight option, has been ingeniously overcome by fitting a headlight to the front forks. This all comes from the mind of a man who was building bikes and riding them before it was legal for him to do so. Bobby’s affinity for smaller bikes has allowed him to bring this machine into the world, and we are glad for it. I’ll finish up by quoting the builder himself:  ‘It is a terrifying blast to ride around town, revving out to 12500 rpm’.

  • Nicky

    any photos with the fairing off?

    • arnold

      On the website about three pages in. Some bit of phenomenal work and variety there.

  • dedleg

    Fairing’s kind of cool as fairing goes – not my thing. Bet it looks badass with it off though – that slender tank is awesome.

  • blackbird.

    Humm, good bike. I gotta be a little critical of the photowork, sorry my man. Second images goes in your face art house. The blurry edges plus saturation = miniturazed object. The framing is difficult here. Are we looking at a presentation of your shops bike? Or are we to see a photo of a really small motorcycle? Digital tilt/shift can help some landscapes done right, in this case it really obscures whats being presented, your beautiful work. Aslo, the third picture is low quality, heavily pixled and all fairing. Where’s the bike? I wanna see it, i bet it looks great!!!!!!!

  • I really like dolphin fairings and this one is no exception. Nice touch to put the headlight on the fork leg – no need to cut up the nose of the fairing. Well done.

  • itsmefool

    Oddly, I like it…really nice bike. Plus, there’s seems like plenty of room for a little nitrous motivation.

  • revdub

    I’ve been following this one for a while. Bobby builds awesome bikes. His fabrication skills are envy-inducing. The fairing looks so good. I’d love to take this out and shred some streets. Awesome bike, Bobby.

  • Oldnbroken

    Hidden compartment in the tank, very clever. Headlight on the forks, off on a smart tangent. Yamaha RD’s a great piece of the 70’s. I know where one of these things is just sitting and doing nothing so this little white piece of smooth curves has me thinking about getting my wallet out.


  • AndrewF

    How can this be road-legal without the headlight? I just want to know what country/state has such relaxed attitude to regulations – it must be a paradise on earth 🙂

    • The headlight is on the left fork leg – very clever.

      • AndrewF

        Yeah ok I missed a bit of text in all the excitement, sorry. But that light mounted low down on the fork is not a headlight – I don’t think that would fly with our nanny state anyway.

        • bobby costello

          the headlight is actually higher than the factory honda civic headlight height

    • arnold

      I often read, think, and think again, despite the beer, before posting something ___for ever___ silly. Manx is a gentleman in his restraint.ald

  • Van Bo

    simply a beautiful bike

  • I’ve been watching Bobby put this together and it is beautiful. Absolutely love it. Fantastic work Bobby.