CONSTRUCT A MOTORIZED TRIKE
A CASUAL CHALLENGE TO BUILD A DRIFT TRIKE LED TO EIGHT MORE AND A SPECIAL RALLY
Cambridge man Kim Dawick knows a thing or two about building drift trikes — he’s built nine of them and no two are exactly the same.
His plan was the opposite of creating a production line — that would be too boring. He has tweaked the design from build to build, but not through any process of refinement. The changes were driven by the parts that he had on hand and wanting to make them look different. “It just encourages you to be a bit creative,” he says.
“For me the most important thing was just to keep the cost down.” That’s something that many successful capitalists would agree with but Kim’s motives are different. He was building these for friends, not for profit. And he has no intention of building them commercially.
“I haven’t asked for money for any of them; it’s just for fun — but I didn’t want to throw $5K at it,” he says.
Can you add an engine to that?
Kim has a long history of adding engines to toys. He has several motorized scooters in his garage, featuring outrageous expansion chambers, the first of which he hotted up when he was 19. He worked as a mechanical engineer but has spent
“I haven’t asked for money for any of them; it’s just for fun — but I didn’t want to throw $5K at it”
most of his time as a professional hunter for the Department of Conservation (DOC). He’s now a structural inspector for the department. Being handy with a welder and a lathe are the most complex skills required; the rest is just down to having the confidence to give it a go.
The idea for the trikes came up when having a beer with a couple of mates after seeing some similar homebuilt drift trikes on YouTube. One of his mates half-jokingly prodded Kim to build one, so he tucked the idea away, got stuck in and, a few weeks later … “I made him one as a surprise for this 40th,” says Kim.
A trike Grand Prix
Now, at this point, Kim had only built one trike, but he has a lot of mates, and all agreed that it would be a lot more fun to race them at their own Grand Prix event. So, naturally, one of his mates said that he’d arrange the venue, food, and drink if Kim would build the trikes. “Be careful,” said Kim. “I might just do it.”
This idea also took hold. Once Kim had finished the ninth, planning for the event got well under way. “I just thought it would be great to get the old crew back together,” says Kim. “We all used to be into cars and doing them up, so each bike has a bit of the owner’s personality in there. If you had a yellow Monaro, you get a yellow trike.”
Just two of the nine have two-stroke motors, one 50cc and a tiddler with just 33cc, while the four-strokes use Honda’s 212cc stationary engines putting out a whopping 6.5hp (4.8kW).
None of the trikes is exactly the same
as another. “They are all like your children,” says Kim. “You don’t have any favourites — except you do.”
His own favourite is the titchy twostroke: “No doubt the four-strokes are faster but I just love two-strokes and the fact that even though it’s only 33cc it’s nearly as good as the four-strokes,” he says.
And while the trikes can reach 60kph, and one — modified from a pit bike — can top 80kph, speed isn’t the main objective. “It’s all about losing traction,” says Kim. “These things are like drift cars on three wheels.”
You will notice that their go-kart tyres are fitted with plastic pipe treads. This ensures that they have minimal grip and will slide at the slightest provocation. As there’s no differential,
“We all used to be into cars and doing them up, so each bike has a bit of the owner’s personality in there. If you had a yellow Monaro, you get a yellow trike”
you couldn’t turn the trikes without their plastic overcoats.
“Go-kart tyres are so grippy that you’d just go straight ahead,” says Kim.
The enthusiasm of the super-slippy rear wheels for sliding also means that Kim and crew have never managed to flip one.
“I’ve got no intention of building a go-kart that goes where you point it,” he says. “That was always the point — no traction.”
To see what he means, check out his first four-stroke machine and its test run at youtu.be/D9SJCgrmESs.
Getting more punch from a two-stroke
The two-stroke engine in Kim’s trike started out at 33cc but he ported it, got a bigger carb, and added one of his bespoke expansion-chamber exhausts. A well-designed chamber can really turn a two-stroke engine into a fire-breathing demon. Getting the right swirl and draw in an expansion chamber is quite an art, but Kim says that you can get tips on anything from the internet now.
He also bounces ideas off a friend in the US who also likes to add an engine to anything.
He says the flashest trike is for his friend Naomi but mostly because he picked up half a go-kart at a swap meet, so it’s got a better rear axle. The meanest is his friend Flea’s, which has a pit-bike engine mounted between the rider’s legs, and is capable of 80kph. That uses an old mountain-bike frame.
Another trike got the tapered bars, headstock, forks, and front wheel from a fat bike, which also featured a flash disc brake. He cut off the standard headstock to weld this on.
“It would be expensive to do that but I had them left over from another project,
and just thought I’d use them to make it more interesting,” he says.
However, Kim has settled on a reliable formula that gives a great result at minimal cost — which is just as important to home builders as commercial success is to entrepreneurs.
How to build a drift trike
The basic requirement is a kid’s trike from The Warehouse or similar. Kim finds the model with the curved spine robust enough for the job. The complete front end — bars, headstock, forks, and wheel are also fine, as is the base for the seat. All of Kim’s mates are tall, around 190cm, so for their trikes he welded an extension onto the seat platform to move it back, but this may not be necessary for ordinary-sized humans.
The business end of the trike is the rear axle from a 110cc quad bike. These axles are already the perfect width, says Kim. They have a flange to bolt the sprocket to. But you have to get new sprockets as the gearing is wrong. Some have centrally placed bearing carriers that simplify the job, but others are offset to allow for different motor designs. That means you might have to weld a section of box steel onto the bike’s central spine to marry it to an offset bearing carrier. “It’s simple enough,” says Kim. “It’s all
mild steel and weldable.”
The wheel hubs also have to be turned down and redrilled so that they can be bolted inside go-kart rear wheels. The axles come with a disk brake fitted, complete with calipers and hydraulics. Some early models had drum brakes. One of Kim’s bikes has that arrangement but the disc brakes are simpler and better, he says. While the trikes have a simple bicycle-type front brake, they aren’t very strong. The rear brakes — even with the low traction plastic treads — work much better. They are also great for initiating the skid.
A $20 engine score
Kim says the best-value engines are the Honda, or Honda-clone, 6.5hp stationary engines. These unburstable units are now very popular for kids’ go-karts and a whole range of accessories has grown up around them. He picked up a brandnew engine advertised as faulty after it had been returned to the vendor. At a cost of $20, with another $20 for the courier, Kim thought that it would be good for parts. The engine wouldn’t turn over — for the simple reason that it had been filled to the brim with engine oil and was hydraulically locked. Kim
drained it to the right level and it fired up first time. Perhaps a second engine will also be coming on the market soon, if the previous owner has done the same thing to his replacement engine.
If you are planning a build, Kim says that it’s worth writing up a parts list, but it’s a short list. You need the trike, axle, motor, clutch, chain and sprockets, wheels and wheel sleeves, twist-grip throttle, and throttle cables.
“I like to buy everything second hand and if you are not too fussy what they look like you can get a bargain. You could probably build the whole thing for $300,” he says. “If you were buying everything new it could cost $800.”
Sourcing parts is not hard
Kim tells us that a man in Te Puke imports go-karts for parts. A pair of wheel rims usually costs $60 but Kim bought eight at a discount. Besides go-karts, there’s also an industry supporting minibikes or pit bikes, which are another source of cool-looking aftermarket parts, such as air cleaners and exhausts.
He scours internet trading forums and swap meets for second-hand parts. If you want to get straight into it, local suppliers like Storm Parts offer good service for things like sprockets and chains, and they can offer overnight delivery.
Kim says the best place to start is with a donor 110cc quad bike. He says they get left outside and go rusty and will often be advertised at a $1 reserve. “You can generally get them for less than $50.”
The main part you want is the axle but if you get the complete quad you also get the brakes, master cylinder, and lever too. Usually the motor won’t work, but if you can get it going again it makes life simple. “That’s what Flea’s bike is — the motor worked,” says Kim, “and if you only get the axle and brakes it’s still a good deal.”
You don’t need a whole quad bike — Kim says that you can pick up the rearaxle assembly alone, with no brakes or calipers, relatively easily on internet sale sites for just $65. After all, he has found nine of them, all told.
“Even so, parts are pretty common, so you could get a disc rotor for $10 or the sprocket for $20 or $30,” he says.
Kim explains that the sprockets you need for the 6.5hp trike are a 72-tooth rear and an 11-tooth front with a pitch of 35. You also need a centrifugal clutch for a ¾-inch splined driveshaft and
the 35-pitch chain. The driveshaft is threaded, so you need to finish it off with a bolt and washer to stop the clutch walking off the shaft.
Installing the power plant
The next step is to marry up the motor to the frame where it will align with the sprocket on the axle. Kim says that with the last five trikes he simply welded a boxsection frame to the rear of the carrier. He bolted the engine to a mounting plate and slid that along the box-section frame until the chain came tight. He marked it and welded the mounting plate in place. He says that you could cut slots in it to make it easier to adjust the chain later but “the lazy way” of adding washers to the mounting bolts to raise the engine worked just as well.
Another thing to make sure of is that you install some kind of chain guard so that if the chain breaks it doesn’t flail forward and hit the driver.
Kim designed and made his own exhaust pipes and even some mufflers. That’s half the fun of it. He was keen to get variety in the field, so looks were important.
Some of Kim’s bikes feature BMX pegs instead of pedals, but Kim says that’s just on the bikes that had standard or motorbike front wheels, which don’t have pedals. The trike front end has pedals on a freewheel hub, and they make perfectly fine footrests. Kim says there is no point changing them.
He says that you could weld bolts onto the forks for BMX pegs but you wouldn’t be able to use the axle in the freewheel hub, so he reasoned that it wasn’t worth it: “You can rest your feet on the standard pedals and it’s absolutely no problem.”
Some unique touches
Standard plastic tanks look a bit ordinary so on several bikes Kim replaced these with old fire extinguishers painted and labelled to look like nitrous-oxide tanks. He made brackets and carriers to hold them at dramatic angles. So cool.
One of the essentials of the drift trike is the plastic rear-wheel sleeve. Kim had some culvert pipe of just the right size handy but says it’s hard to come by. The standard item is Humes stormwater pipe with an internal diameter of 259mm. It’s available in 6m lengths for about $500 but it’s also available pre-cut in the 130mm widths needed for tyres at $90 for the pair.
“It’s easy to install. It’s just a matter of letting down the tyre, slipping it over by hand, and then re-inflating the tyre, which holds it firmly in place,” he explains.
Kim bought the sets of sleeves as he had not set out to build nine bikes, but says you might want to consider the 6m length, as having just one trike is never enough.
“We had several guys who like their macho cars or trucks and were reluctant at first, but eventually they’d give in and then you could never get them off them,” says Kim.
Building drift trikes is only the start of the fun.
A beautifully organized shed made it easier for Kim to keep nine trikes on track
Above: When Kim accepted the challenge to build nine trikes, keeping the costs down was vital to a successful outcomeLeft: Now to put it all togetherBelow: Weld a bike frame to a quad bike rear-axle bearing carrier and you have the bare bones of a trike
Adding motors to things generally makes them more interesting for Kim. He built a school trolley derby entry for his nineyear-old daughter that he designed to look like a go-kart. She came second in the race at school but Kim soon got bored with pushing it up the drive at home so added a motor to turn it into a real go-kart
This is Gubby’s four-stroke engine and even though these engines are faster, Kim loves twostrokes because although they have pint-sized cylinders in comparison, they are nearly as good as the four-strokes
Kim tweaked the design from build to build, with changes driven by the parts that he had on hand and could adapt
The nitrous look
These trikes are made to drift; no grip or traction required here, thanks
Kim has also flirted with furnituremaking. One of his earliest pieces is a chair that he made for his future wife, as you do, which combined his metalwork and wood-working skills. As his wife is into art, at his brother’s suggestion he turned what was going to be a plain seat into an artist’s palette. Kim has also built some nifty wooden units for storing bangles and necklaces, a TV stand inspired by apple boxes, and a 40m flying fox for his three children on their place outside of Cambridge. Kim’s time in the shed works for all the family