More like a Bullet ‘It’s perfectly tractable… I use it to commute’
This Interceptor 650 has just obliterated the land speed record for its class. And you can fit most of the go-faster bits to your Enfield twin
Owners of Royal Enfield 650s, take note: there’s plenty of performance tucked away in that humble air-cooled twin. Australian Enfield dealers Midlife Cycles recently managed to crack 132mph on their unfaired 650 with no turbo, supercharger, nitrous or fancy fuel. The team smashed a world land speed record for the class that had stood for four years.
‘It’s changed our perspective on what a Royal Enfield can do,’ Midlife Cycles’ owner Michael Catchpole tells Bike from his base in Melbourne, Australia, ‘and many of the engine modifications are directly transferable to a road bike. I run a road-going version of the race engine in my Continental GT650 that I commuted into work on this morning.’ Lifting the 650 twin’s top speed by over 30 percent and raising its peak power from 42 to 65bhp at the rear wheel does take a fair bit of work though. Starting at the top-end, Midlife’s tech guru Andrew Hallam increased the inlet port size by 1.5mm and gas flowed the head. The valves were replaced by ones made by Hallam’s company HRA, who also supplied an extremely hot camshaft – don’t forget, the Enfield only has one.
Because the team wanted to keep the capacity at 650cc to show what’s possible without throwing big bore kits at it, they left the cylinders alone and just replaced the pistons to help increase compression from 9.5:1 to 11:1. The con rods were shot-peened to improve durability and the crankshaft was balanced.
‘We dyno’d the salt racer [it competed at Lake Gairdner in Australia] during development and got 65bhp at the rear wheel but it wasn’t finished, so the final output may be more,’ says Michael. ‘It was totally reliable too. Our rider Charlie Hallam [brother of tuner Andrew] had to pre-qualify because he was a first time salt racer, and he actually broke the existing record on his first run. But what was pleasing was how many runs the bike did without issues – I think we did more runs than any other bike, breaking the record again and again.
‘We didn’t have to touch it – there was no suggestion that it was going to do anything other than back-to-back runs. We just changed the gearing and that was about it.’
Michael’s road going version is equally civilised, and looks identical to a standard machine apart from a fruity exhaust. ‘It’s perfectly tractable still and I use it to commute most days. It runs the high compression pistons, bigger valves, a road competition camshaft – not quite the same as the racer’s – modified intakes, and a much better exhaust than standard. It’s running close to the specification of the race bike and it’s quick – you can surprise a lot of people on it.
‘We’re offering customers performance packages in stages. The full road performance kit that I run is AU$7000 (£3850), which is a significant amount, but then again if someone bought a new Interceptor and had all that done it would still be a lot less than a Thruxton 1200 and about the same as a Bonneville T120.’
So what’s next? Time for a big bore kit? ‘No, we’re going to stick with the 650 capacity because we want to show what’s possible. And 650 has always been a traditional capacity ever since the days of Triumph Bonnevilles and BSAS. But there’s more horsepower to be had…’