South African Built 500cc 2-stroke to take on Roof Of Africa 2023
Occasionally we bump into some really interesting people. This time round, the enthusiastic gents from Alpha Performance Bike Tyres in Silverlakes gave us a call and invited us for a cup of coffee. “There’s an interesting project on the go as we speak, you’d better come and grab the story…”
So we did. The date and time was set and we popped into the shop and met with a mighty interesting engineer by the name of Koos Zietsman.
Not only is he the leader of the team building the bike for this Roof Of Africa project, but next year, he is planning to hit the Bonneville Salt Flats during Speedweek for an attempt at the land speed record. On an SA built big bore single cylinder 2-stroke!
But that’s another story you can read all about it in RideFast.
The Roof Matjien:
Enduro man Riempies Pretorius approached Koos a while back with the idea of building a “Special” Roof bike, and at the time Koos kind of nodded and forgot about it. A few months later, Riempies was back with details of a kit that you can buy in Canada that costs as much as your car, house and bike…
Koos was intrigued and first gear clicked in.
“We can do it for a lot less and it will probably be better,” was his comment.
The bait was taken and as we type, that line is running.
Team Matjien.
That’s the name of the team responsible for these madcap adventures – a team that includes some very impressive credentials:
We’ve introduced you to Koos, lead engineer on the project. He will be piloting the land speed bike in August 2024.
He has roped in 2-Stroke development engineer Neels Van Niekerk.
Joining them is Gear design engineer, Piet Van Zyl who has experience working on projects for the likes of McLaren F1 cars.
Whilst Riempies is tasked with riding the bike at The Roof, he also happens to be an optronics design engineer.
Hans Fouche is an F1 Aerodynamicist.
Fox Keet is the CAD designer for the LS498 engine for Bonneville.
The frame design engineer is Jock Pretorius who completed Roof bronze as a complete novice in 2022.
The team is rounded off by Ryan Raubenheimer who is a vehicle dynamics simulation engineer.
And it’s all been worked out really scientifically, we don’t even understand half of what they are doing to get it right, but you need to understand that these are not your average braai mechanics. This bike should be the real deal.
The Roof bike:
Now this will be one to look for.
It’s basically a KTM300 XCW chassis with a custom built 490cc 2-stroke dragging it up and over the rocks.
It’s not simply a big bore bike. In fact the only thing that it will have in common with KTM’s 300 is the carburettor, clutch and gears. Note we said gears – not gearbox.
These guys are manufacturing billet bottom end casings and covers, balancer shafts, a new crankshaft, barrel and cylinder head.
The Piston is a Wiseco unit borrowed from a CR500 Honda.
The guys are designing an electronically controlled power valve to smooth things out.
It’s still going to be electric start, with a Lithhium battery and an electric cooling fan.
Of course, the frame will need to be altered to make it all fit.
Plans are for a 12 tooth front and a 54 tooth rear sprocket.
A custom built expansion box and silencer.
50:1 oil fuel mixture.
The bike will rev about 2000 RPM less than a standard 300, but – as you’d expect they’re predicting slightly more horsepower than a 300, 77% more to be exact!
Neels’ simulation software predicts 48KW@7000RPM. Max torque is 68NM @6000.
Maxxis gummy is their tyre of choice for this project.
While the bike needs to be ready for Roof in November, the guys plan to have it up and running by August.
We have asked for a follow up on that – when we will actually be able to see it run – and maybe even take it for a quick blast.
What a project! What an adventure!
Watch this space, we’ll keep you posted.
And…
See you at The Roof!
Sterkte manne!
Scary hearing guys say things like “you can’t find big bore 2- smokers anymore.” I have a small collection… IT425, 465,490, busy with a second 490 build, KDX450 and a 2004 Honda CRF250R roller… dudes were stripping it for booze money for a rally!! Busy putting a spare rebuilt IT490 motor in it…similar (sort of) to what you’re doing now. Exhaust will have to be a custom one-off build. Keep us updated with progress. Good luck.
Love the new look mag, even I can use it. Hope it grows exponentially for you great guys. Viva!