Uncorking a KTM 530EXC With Chad Watts

There are many great benefits of working at a magazine. One of the biggest is the industry people we get to rub shoulders with. From racers to team managers to mechanics, we have the opportunity to hang around some really exciting people and see some extremely cool projects. Recently we were at Watts Perfections, Chad Watts shop in Shelby, North Carolina talking about some of the project bikes he was working on and he told us about a 2010 KTM 530EXC he was modifying for a customer.

If you aren’t familiar with the Enduro championship winning EXC formula, here is a bit of info on it. The liquid cooled 530 engine actually displaces 510cc and features a four-valve OHC cylinder head and an 11.9:1 compression ratio. That top end breathes though a 39mm Keihin FCR-MX carburetor, while power flows through a wide-ratio six-speed transmission with hydraulic clutch. The Engine is wrapped in a Cr-Mo frame, with WP forks up front (11.8″ of travel) and KTM’s simple, non-linkage rear suspension (13.2″ of travel). Despite its dual-sport legality, the package comes from the factory with appropriate spring and damping rates for off-road racing, minimal work has been done to make the bike DOT legal. The big differences between the EXC and its off-road only brother’s lies in DOT approved Metzeler knobby tires, emissions friendly carburetor jetting, taller gearing and a quieter exhaust.

In stock form the 530 is no slouch but Chad’s customer had a few issues he wanted to address. He was looking for more bottom end torque, longer range, and better resistance to overheating. Since the 530 EXC is set up to be street legal from the factory, in order to obtain that coveted license plate, the jetting is super lean, the exhaust system is severely restricted and it has a pile of emissions control hoses/canisters etc. Chad felt the bike would benefit greatly from less restrictive jetting specs, removing the power sapping emission restrictions and opening up the corked exhaust system.

Starting with the cooling system, Chad had ICW weld an extra section onto the bottom of the stock radiators for more volume and bypassed the thermostat system with a set of Samco silicone hoses. From here he removed all of the street legal, power robbing, emissions system tubing and auxiliary sub tank and catch tank and uncorked the exhaust by removing the baffle. He also blocked off the return air tube to create a cooler air flow from the stock Keihin carb. Chad says the 530 comes jetted ridiculously lean from the factory with the main set at 180, the pilot set at 48, the leak jet at 40, and the needle 3rd from the top. To liven things up, he changed these to 190 for the main, left the pilot at 48 and changed to leak jet to 35. He also moved the needle clip from the 3rd position to 4th from the top. Stock position for the fuel/air screw is 1 ¾ out, this was changed to 2 ¼.

The OEM gas tank allows a paltry 2.5 gallons of fuel until it’s full. This is fine if you are riding reasonably short trails. But Chad’s client wanted to go exploring without having his adventures severely shortened by this inadequate fuel capacity. Acerbis makes a 6.3 gallon jug that added the kind of range necessary on some of the rides the 530 was scheduled to see. A Scott’s steering stabilizer was added to reduce fatigue on longer journeys as well as a set of Cycra hand guards to protect hands from flying debris.

The KTM 530’s bottom end torque was the next item on the list to be addressed. The KTM mill makes tons of power throughout the power band but has a weak bottom, especially for a 4t and modifying the motor for better bottom would be expensive. The 530 ships from the factory with relatively tall 15/45 gearing for a final gearing ratio of 3.00, Chad felt a change to 14/46 for a final gearing ratio of 3.29 with a fresh set of Vortex sprockets and DID ERT chain would do the trick. While this may not appear to be a huge change, it was enough to give the 530 a more responsive bottom end hit without sacrificing comfort at higher speeds on the street due to high rpm’s.

The KTM 530 is a solid, well rounded, street legal off-road bike. Uncorking it really brought it to life and made it much more versatile and fun to ride. If you have a 530 you want Chad to work his magic on contact him at (704) 538 9990 or email chad@wattsperfections.com. You can either send your bike in and have him do it for you or buy the kit and install the parts yourself. Either way, both you and you KTM will be stoked you did.

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