If you bought a 2017 or 2018 KTM 500 EXC-F or Husky FE 501 with plans to build a killer snowbike, you'll be surprised to learn just how restricted the latest versions of the beloved 500 4-stroke has become. In fact, in stock form, that bike is going to really struggle to keep up with a 450cc mx bike on the snow. They run lean, have a reed cage in the intake boot and have a very restrictive exhaust. Beyond that, they have a restrictive fuel rail and a fuel filter that impedes fuel flow.
But that doesn't mean you can't get power out of the 500. It's there, it just takes a few mods and some tweaking to free it up.
We're building a 2018 KTM 500 EXC Timbersled ARO 137 with help from ktmandhusky.com's Dave Simon. If you have a history with KTM or Husky 500s, that name is a familiar one. If the 500 is new to you, know that it's not new to Dave Simon.
Dave has designed stuff for the dirtbike industry that is widely spread today. He's written books, magazine articles, had articles written about him, and built engines that have won world championships from jet skiing to motocross. His work has also set land speed records on dirt bikes. Dave's probably blown up more engines than you've started just so at the end of the day, he can assemble KTM 500 EXCs that finish the 1,160-mile Baja 1000 without skipping a beat. Since big power and reliability are key to snowbiking, we've decided to have him help us build a great snowbike.
Here's the first things you'll want to do to get the KTM / Husky 500 ready to rip this winter:
- Eliminates extreme-lean stock ECU tuning.
- Increases horsepower output to the track.
- Improved bottom-end.
- Improved throttle response.
- Improved top-end.
- Easier starting.
- Higher rev limits.
- Allows for use of aftermarket muffler or aftermarket muffler replacement tip.
- Pre-programmed for optimum fueling in 12.5:1–13.5:1 AFR range.
- Easy to tune with three adjustment dials. One for low throttle, one for mid throttle and one for high throttle.
- You can select from 10 different fuel maps.
- Optional handlebar switch to change maps on the fly.
- Diagnostic flash codes.
- Easy to install. Just unplug the stock ECU and plug in the Vortex ECU.
- The stock 2017–2018 bikes have a reed cage in the intake boot right behind the air filter. Yes, your 2018 4-stroke bike has a reed cage. And it severely restricts the airflow to the engine. And, should a reed petal chip and go through the engine... bad news.
- You can cut the glue around the reed cage and remove it. That's the cheapest method. But not the best performance option.
- KTMandHusky.com's Power Intake Tube is a billet insert that keeps the intake tube from collapsing in on itself under power. It also creates a better air velocity. The difference with and without the Power Intake Tube is a bog in throttle response without it.
- You will need a Vortex ECU or a TPS tuner to make this modification work, because it is increasing air flow so much. Fuel needs to be added to the map.
Replace the stock muffler with an aftermarket slip-on or with the KTMandHusky.com Power Cap.
- More air flow through engine.
- More bottom end.
- More mid range power.
- More top end.
- Leans the bike out, requiring a Vortex ECU or TPS tuner for added fuel.
Add a bigger fuel filter to the fuel line and replace the fuel rail on the throttle body.
- Once you start adding fuel to the map with the Vortex tuner, fuel flow is restricted in two areas: fuel filter and fuel rail.
- The fuel filter is replaced by a much larger unit from KTMandHusky.com.
- Next, replace the stock fuel rail on the throttle body with the high-flow fuel rail from KTMandHusky.com.
- This reduces hard starting, acceleration lag, stalling and flame-outs.
- The 2017 and 2018 500s have emission control systems that
From there, there are additional items that will only add more power and make the bike run even better on the snow (Grunt exhaust manifold, bigger fuel pump, high flow petcock). We'll get into those as we ride through the season.
Stay tuned to Snowbike World's Instagram page for more updates.