It is quite something when you can radically improve both the performance and handling of a seventies machine. What is even more special is if, while carrying out those extensive modifications, you can still retain most, if not all of the original spirit and feel at the same time. This is exactly what Dave Newitt of the Thumper Club has achieved with his superb XT500 Supermoto machine. The engine is pure XT and yet, thanks to a few crucial improvements, it has a significantly more modern, and rev happy, style about it.
The chassis too, is unmistakably XT, with the standard frame cradle remaining intact and yet, with some very trick stuff now hanging off each end, immeasurably improving the stopping and handling. All Dave has done is remove lots of the standard parts and replace them with newer and more up to date stuff, and yet the weight has just fallen off. Weighing around 60 pounds less than an XT should, the Supermoto makes for quite a performer. Not having to haul so much chassis around is a big bonus for an engine producing so little horsepower in the first place. The result is a thumpy, tractable machine that could “have a go” at any new Supermoto machine and yet, still slip back into a time of flared jeans and cut off denim jackets without attracting too much attention.
Dave originally bought the donor machine as a source of spares for the immaculate restoration seen in CMM issue 214, the plan was to strip the machine down and move on the parts that remained via eBay. Once robbed of the necessary parts the remaining bike was still complete enough to start his brain thinking what if? With so many restorers seeking the holy grail of as new, or even better than, condition, Dave decided to show how you could keep the original looks without having to source the difficult to find, and often prohibitively expensive genuine parts. With the XT having more racy siblings in the HL and TT models the decision what to do was an easy one. Dave decided to build a full on Supermoto machine, using as many Yamaha parts from other machines as possible, with the emphasis on creating a fun machine.
The Supermoto began life as an American spec model imported to the UK. Thankfully it had been well cared for by its previous owner, having received a Wunderlich twin oil feed conversion to the rocker box area and many similar updates before Dave got his hands on it. The motor was damn fast too; a quick spin up the road soon revealed the work was not just external; this one was a real flyer.
The end result, after just six weeks of intense work, is the XT Supermoto seen here. Some problems did arise, like the wider rear wheel and tyre fouling both the swing arm and brake torque arm, but ace mechanic Dave quickly sorted these, eventually getting the Yam frame to accept a wider swing arm. Once a pair of YZ250 yolks had been grafted onto the front end, 50mm YZ 250, up side down, forks were slid in place enabling the use of a 240mm disc and a Nissin brake caliper replacing the tiny, single leading shoe, drum stopper of the XT. Spacers were machined up to fill the 5mm gap between the 55mm fork yolks and the fork legs, as the parts are from different models of YZ, even so they work very well together.
Using galvanised spokes provided by Central wheels, Dave rebuilt the wheels himself. The original rear hub and the YZ250 front item was laced to Takasago rims, this allowed the use of wider, smaller diameter tyres, more in keeping with the Supermoto ethos. The new wheels were fitted with grippy radial rubber, the result is a sharp steering machine that can be thrown around on the road as if it were a fraction of the size it actually is.
Aesthetically pleasing to the eye and equally nice to ride, the XT performs the tasks of the original and much, much more. Despite looking well thought out and the subject of lengthy planning meetings, the orange and aluminium tank wasn’t actually meant to be. The original plan was to get the bare aluminium anodised, however, an accident early on in the building resulted in a dent near the filler cap and the only option was to paint the upper section. Once again, Dave has made the best of the situation, the resulting colour scheme is striking and, at the same time, a homage to the XT. Simply by thinking in straight lines and logically, Dave over came the few niggling problems he encountered and the result is plain to see. The livery is enhanced further with a cut down front universal mudguard, while the standard side panels and rear guard remain intact. The flashes of orange and custom made logos finishing the job of nicely.
Once the project was something like complete the initial road testing began. Right at the top of the early failures was the standard Yam clutch that simply could not cope with the rigours placed upon it by the extra horses. An EBC heavy-duty kit, comprising of plates and springs, was fitted and, since that time, nothing further has been heard from that department. In use the engine is “good old dependable” XT but, as if on steroids, much more willing to go. Throttle response from the 34mm Mikuni carburettor is instant, as is the lurch forward, stretching arms to the max and sliding the rider rearwards, greatly exacerbating the wheelie ability in the process. Off the gas for a corner and you can’t load the front wheel as much as a modern Supermoto machine due to the excessive weight and positioning of the big Yamaha lump. What you can do though is ride it a like a conventional road going machine and keep the wheels more in line, making the most of the grip to get the power down in the process. The horsepower is up by half as is the torque, which peaks at a staggeringly low 2500 rpm. Wheelies off the throttle can be had in the first three gears and one must show great care when cracking that throttle open while leaning as the front wheel will just leave the tarmac and head for the skies. This will happen regardless of the angle you have the bike over at, just get ready to lean even further still to reduce the understeer this process creates.
It was while pushing the cornering abilities to the limit that we found the only potential fault with the Supermoto XT. The rear Avon Azaro AV26 tyre is the largest that can be fitted within the swing arm, but this is still not wide enough to correctly fit the wheel rim. The profile isn’t quite right as the rim is a little too wide and a few times during the test we found ourselves running off the edge of the tread. This was at its worst when low down in the rev range as the torque was enjoying greater leverage over the tormented rubber. Massive power slides were the result though, the engine allowing superb control over them for the maximum grin factor to be had. For those a little less disposed to such riding, it is a simple matter of lifting the bike up, a few degrees onto the fatter part of the rear tyre, before hitting the go button, I just couldn’t help myself. Just in case you do get it wrong large plastic crash bobbins are fitted at each corner of the bike to stop excessive damage.
Every inch covered while riding on the Supermoto is matched by a super wide smile, fun is why this bike was built and it delivers by the bucket load. Of course, it is in its element being thrown from left to right, and back again, down a twisty B road, or leaping over hump backed bridges. Checking out the top speed shows it is no slouch either should you wish to travel further a field. I would imagine however, that the vibration from the big single might get a little fatiguing over long journeys, you don’t notice it along country lanes as you are having too much fun to be bothered buy such things, get a long A road however and your mind would be less pre occupied.
With cycle parts chosen from a number of sources the result could have been a disaster, thankfully this isn’t so and the machine handles superbly. Steering is far sharper than any road legal XT ever previously encountered, no doubt a combination of the jacked up rear, and the profile of modern Radial rubber. Sitting as high on the road as this machine does could have proved troublesome but Dave has thought long and hard about this motorcycle. To help the rider maintain a good foot hold when not moving, two inches of foam have been removed from the padding before being recovered with a custom made seat cover, complete with matching orange piping. Extra height would not usually be a benefit to the age old problem of getting an XT to burst into life, the precarious technique of balancing on one leg while you prod the starter with the other is never a good one on a standard machine, let alone one even further away from terra firma. Thankfully this pepped up machine is a cracking starter and struck up first time, every time. In fact it never missed a beat during our time on it. Quite surprisingly the ignition is unmodified, still retaining the points and coil set up as originally fitted by Yamaha. It works and clearly, very well, all the way up the extended rev range that this machine enjoys.
Of course no production is complete without a stunning sound track and this bike doesn’t disappoint. A K&N filter is all that separates the outside world from the inlet side of the engine while a short and stocky, cut down, Scorpion end can does little to calm the explosions going off with every other revolution of the crank. Attaching the silencer to the head is a custom-made stainless steel header pipe, which is nicely colouring up thanks to the heat process.
Little in the way of social niceties can be found on the bike. A digital speedo, actuated by a metal weight attached to the brake disc, provides enough information to keep your license intact, while mounted on the head light shell are the neutral, high beam and oil warning lights. This integration of components keeps the slim styling as neat as possible and is typical of Dave’s approach to the whole concept.
Dave is pleased, as indeed am I, with his latest creation and he should be. Without a firm idea or plan in mind about the end result, he has got stuck in and reacted to each and every problem positively. The Supermoto looks every inch an XT500 and yet, more alert and ready for action. The engine, now thirty years old, is as ready and willing as a new machine ever could be, maybe even capable of taking on some of the latest Supermoto machinery and getting the better of them.
Yamaha XT500 Supermoto Specifications
- Engine: 4 stroke single cylinder aircooled SOHC
- US spec 1E6 model
- Capacity: 499.35cc
- Bore & stroke: 87mm x 84mm
- Compression Ratio: 9:1
- Carburetion: 34mm Mikuni
- Max Power: 45 bhp @7500 rpm
- Torque: 37ft lb @ 2500 rpm
- Ignition: Contact breaker
- Transmission: five speed, wet clutch
- Starter: kick ( and pray)
- Frame: steel single down tube
- Suspension: 50mm telescopic USD forks, Hagon hydraulic shocks 4 way spring pre load
- Wheels: 120/70 x 17 front, 140/80 x 17 rear
- Brakes: 240mm disc Nissin 2-piston floating-caliper front, 150 mm single-leading-shoe rear
- Wheelbase: 1415mm
- Weight: 115 kgs
- Fuel capacity: 8.8 ltrs inc. 2 ltr reserve
- Top speed: 94 mph
Check out www.yamaha-xt500.co.uk
Yamaha XT500 Supermoto Special Gallery