How to Build a Custom Motorcycle - Underwater Sea Bullet
Aaron Huber

How to Build a Custom Motorcycle: DO’s & DON’Ts

If you’re considering how to build a custom motorcycle, here’s a handy guide to help you get started. There are three methods you can take with ascending difficulty and skill requirements.

In this article, we uncover those methods and the skills you need to build a motorcycle.

How to Build a Custom Motorcycle: Now is the time

1979 Honda CB750K For The Bold Custom | Image by Nate K

The man, Big Brother or the nanny state, call it what you will, they all seem hell-bent on turning motorcycles into noiseless jelly moulds. You only have to look at current legislative hoops concerning noise, fuel evaporation and emissions (the big three) that manufacturers have to jump through.

Thanks to the big three, the air-cooled motorcycle is in its death throes. Think I’m a little dramatic? Well consider this, BMW has sunk millions into producing the R nineT, however, without its most recent major update, Euro 5 emission laws would permanently have removed the R nineT from your dealer’s sales floor.

I’m not here to scare the bejeezus out of you but merely to grab your attention to make you realize that now is the time to customise your bike.

Admittedly, there will be lots of people out there who don’t care whether they ride a hairdryer or not. If you’re reading this though, chances are two-wheeled raging against the machine is not only a way of life and moral duty but also damn good fun.

Before we examine the nuts and bolts of customising your wheels, let’s address the elephant in the room. Namely, is there such a thing as an ugly custom bike?

Yes, of course, there is. However, there is a ‘but’ and it’s a massive ‘but’. Regardless of what shade of lime green you hand paint your bike or how high your T-bars are — if it’s a result of your sweat and effort then good for you.

If however, you’ve trailered your new toy to some boutique and said ‘call me when it’s farkled‘, then you may as well blow the money on your man cave or your lady lair. Notwithstanding the finished build, the ugliness is in the lack of soul.

Building a Custom Bike: The Nuts and Bolts

Okay, enough of my pontificating and on to the nuts and bolts.  There are three paths you can ride down, towards the dream of creating your own custom:

  1. Work with what you’ve got:

    Customise your existing bike

  2. Donor Bike:

    Get an idea in your head for a custom project, find a donor and set to work.

  3. Build from the Ground-Up:

    The planets finally align and the dream of building a ground-up, full-on custom bike, eventually becomes a reality

’83 Kawasaki LTD 550 – Image: @motophotonate

1. Custom Bike Build: Work With What You’ve Got

This option can take many shapes and depends a lot on how deep your pockets are and of course how long you can do without your daily ride. Right now you can buy handlebars, grips, bar weights, mirrors, lights and indicators in a plethora of shapes, sizes and finishes.

The trick to this is to choose a combination that works. Assemble all the accessories first so you can put them on as you would with one large kit.

By assembling it all first, you can make sure you have everything you need. LED indicators, for instance, need a different relay while handlebars sometimes require new brake or clutch cables/lines. This method also ensures minimal downtime.

You can also kick things up a gear by changing the seat or reshaping the stock and having it recovered by a local upholsterer. Exhausts, regardless of whether they’re slip-on silencers or full systems, can also give a whole new look (and sound) to your ride. Don’t go overboard!

Customising isn’t all about adding bits on either. Bobbers and cafe racers are all about shaving weight, taking things off or cutting down.

Minimalist Ducati L-Twin Custom Bike Build

Just be aware that with the stock gas tank, side panels and mudguards removed, most mass-produced frames are a mess. Nasty lugs, tabs, pressed steel fastenings and ugly machine welds are in abundance.

See a bike with clean lines, smooth frame rails and minimal cycle parts and that effortless-looking style is down to countless hours of hard labour.

This category also includes performance customisation. Typical mods include USD forks, braced swing-arms, multi-piston brake calipers and wavy discs. Dumping all that plastic off your crotch rocket is also very liberating – who says Streetfighters aren’t custom bikes?

2. The Donor Bike: Selecting a Donor to Build a Custom Motorcycle

This route is one I’ve travelled many times and one that can be very rewarding. This method allows you to create a more comprehensive look based on a specific model of bike and is usually the result of an itch that’s needed scratching for a long time.

The downside is sourcing a suitable donor bike. It wasn’t that long ago that, mid-sized Honda Fours lay in garages gathering dust. Yamaha XV’s were an acquired taste and owners couldn’t even give away big Suzuki singles.

Now, thanks to masterful builds like the Vincent-inspired Virago by Hageman Cycles or Classified Moto’s endless stream of exquisite builds based on Japanese Twins or 53 Fast Living’s Savage bobber – legions of yard-builders have been inspired to transform Japanese, classified bike finds, into café racers, bobbers, brats,

scramblers and trackers. Suffice it to say that Japanese bikes are becoming increasingly difficult to source or aptly, prohibitively expensive to buy. The CX500 is a prime example. This bike with its numerous colloquial pejorative monikers, has now become one the most sought-after by yard builders.

Honda’s CX500 is now much coveted on eBay – Image: Gijs Coolen

Don’t panic though, just because there are gaping holes on eBay, needn’t necessarily mean those bikes aren’t still out there. You may, however, need to be a little more flexible with your choice of donor and get a bit more creative with your search.

Check Out the Motorcycle Classifieds

In the UK and Europe, you’ve got regional, as well as country-specific, classifieds, both online and in good old-fashioned paper format. The USA seems to be dominated by Craigslist but likewise, still has state-specific moto classifieds.

You can also put up wanted ads in the local supermarket, bike accessory shop, or even in your guitar shop.

Talking of ‘shops, dealers will take in virtually anything to move a new bike. The old stuff never makes it to the showroom floor and they are often sold off cheaply, so it’s always worth asking. 

Be Flexible in Choosing a Donor Bike for your Custom Bike Build

As mentioned earlier, you may need to be a bit more flexible in your choice of donor bike. So, instead of a late ’70s Honda CB750 Four, look for a much later CB 600 on eBay, a CBX750 or a Nighthawk 750, again on eBay.

If you want a big twin, forget the XS650 and hunt around for a Suzuki VX800 while they’re still relatively undiscovered.

The whole 750-1200 range of first-generation, Hinckley Triumphs is all modular. This feature means you can have limitless fun swapping stuff around to create the ultimate hybrid. Don’t worry, there are still donor bikes out there, just don’t buy a dog through lack of patience.

Custom Air-Cooled Triumph Motorcycle
Air Cooled Bonneville – Image: Dan Burton

Anyway, before you do the deal on your donor, there’s a whole host of research to carry out, which could ultimately affect your final choice. So first of all, come up with a look or style for the project, you might be bobbing a Hinckley Triumph, or café racing a Gold Wing (guilty on both counts!).

Don’t Reinvent The Wheel: Copy and Adapt

Once you’ve decided, Google the hell out of it. Search for terms like ‘Hinckley Triumph frame’ or ‘4 into 4 Gold Wing exhaust.’ If you’ve got ideas for frame mods, or want a clue of just how tricky a modification is, I guarantee you some enterprising soul will have tried it before.

This advice is not about ripping off someone else’s idea. This is standing on the shoulders of giants and the karma is paid back when you post photos of the bike you’ve built.

Anyway, the golden rule here is to measure twice and cut once. In other words, if you’re making any frame mods, (like hacking the sub-frame off) think your actions through properly. It may take two minutes with an angle grinder but can create hours of headaches later when you’ve got to remount electrics, mudguards and exhausts.

Outsource Specialised Jobs

Finally, a word of warning to the wise! If you’re making serious alterations to a frame, such as goose-necking, top tubing or hard tailing and you haven’t got the skill or jigs to handle it, take it to a fab ‘shop. Don’t gamble with your life to save a few bucks.

3. The Ground-Up Custom Bike Build

The Holy Grail of custom bike building, which theoretically has the potential of being the most satisfying.  One look at the amount of ‘unfinished projects’ available on various sites though, also hints at the dangers.

Large Capacity V-Twin – Image: Aaron Huber

Adding individual touches to your motorcycle is an excellent way of making a bike, your ride. Completely altering the look of your wheels by adding or removing larger components marks you as a serious custom lover. Completing a ground-up project and putting in the miles on it, allows entry to the elusive and exclusive, built-not-bought club.

Don’t Sweat it: Building custom bikes is not for everyone

This road isn’t for everyone; so don’t get riddled with guilt if you haven’t attempted it yet. For a start, it’s a total money pit; forget about it being the cheap way to a chop. It can take forever to finish and you also need a secure, dry, well-lit

workspace with a reliable power supply. I have seen show-winners, built-in tiny sheds – using an electrical extension from the kitchen. But while it is possible to do this, it takes mega-dedication. 

Birdcage Storik Custom Motorcycle Fabrication
Wireframe Mockup [Storik] – Image: Nate K

You will also notice that many bike builders who opt for a ground-up build use big V-twin engines. This is because they’re the only type of engine you can buy new over the counter. If you want to create your ideal custom bike using any other kind of engine, it will have to be the power plant out of your own bike, or it’s back to the donor again.

You can, of course, buy a used engine from a breaker’s yard, however, building a custom bike around it without stripping and rebuilding is Russian roulette.

Research, Shop-around, Haggle and Sketch

Make plenty of sketches. Use ideas from different sources; research will save you time and money in the long run. Shop around for parts, if you need to fabricate anything, then get a few quotes. If you get a new frame made for you, ask what extras you get with it. The seller may throw in bearing cups, or an electric box.

Don’t be over-ambitious with your design. Remember, it’s got to be able to go, stop and handle. If you haven’t ridden a hardtail before then do so before you blow thousands building one. Trust me, you’ll either love it or hate it.

The same goes for fatback, or skinny front wheels, hand gear-changers, forward foot controls and long forks. They may arguably all look cool but are not necessarily easy to live with long-term. This genre is one where you have to suffer for your art.

Lastly, yet most importantly, set a budget!

Finally, think of a budget and timescale for your ground-up project and multiply it by two. You’re not taking part in some pretend reality show with time-lapse footage; this is the real world with bits that don’t fit and parts that never arrive.

Still, want to build your own custom bike? Excellent, whatever route you choose to go down, the customised bike world awaits.