A Husqvarna FC450 Rockstar Edition transformed into a devoted hillclimber is center stage this week. The bike was built for Kyle Redmond to use in the Great American Hillclimb event in Billings Montana. With three slim weeks before the event, Kyle and Erik Jones slammed the throttle to the stops to get this special stretched machine built and tested. Erik Jones was responsible for coaxing more power out of the motocrosser. He owns Jones Engine Development, and his primary business is building NHRA drag race engines. His hobby is riding dirt bikes and is himself a very adept hillclimber. He also put together the ignition mapping, programming the GET ECU and configuring the necessary hi-octane fuel that would work best with his engine modifications. We’re still not sure what Kyle did but he claimed to be working 11-hour days helping the mad scientist. Here’s a look at the build, some input after three test sessions. Next month we’ll have full coverage of the event and Kyle’s escapades.
FMF sent us a Factory 4.1 titanium exhaust, FMF has always made great power and is the industry leader in high performance exhausts. The titanium system is also lighter than stock and produces much more flow so the motor can breathe.
We used SRT wheels and hubs. They are stronger than stock and the titanium color really makes the bike look good. We decided to try the tubeless system mainly for weight, and it also helps keep the wheel from spinning on the rim. Earlier, we had problems with this, but the 110psi bead lock tubeless system assures that would never happen. With all that power to the rear wheel we need a strong chain so we went with the Regina enduro chain. The paddle tires would hook so well that we needed custom 54t and 56t sprockets so the bike would rev properly. DDC sprockets hooked us up with very strong steel rear sprockets.
Erik Jones mounted the FC450 head on a Saenz D680 flow bench to measure the changes he made. Clay is used on the Intake port entry to round the sharp corners of the intake port flange during flow testing. The stock head pipe is installed during the exhaust port test to simulate the direction of air flow when the engine is mounted in the bike.
Erik figured out the best shape with clay, then used a special epoxy to raise the floor of the intake port. This increases air speed on the “Short Side” of the intake port and eliminates the turbulence problem in the stock FC450 head. Turbulence can cause the Intake port to “Air Lock” at certain RPMs and can lead to tuning problems as well as flat spots in the power curve.
Because the Rockstar Edition is a new model to the Husky line up there are very few aftermarket parts available. One example is the camshaft. It is a shared idea throughout the motorcycle industry that these new camshaft designs are too complicated for the aftermarket motorcycle industry to reproduce. The production camshaft works really well for this hill climb application in stock trim, it has really good mid range power and a smooth power curve. Jones Engine Development is in the process of producing a custom billet camshaft and revised rocker arm system to take full advantage of the fully ported cylinder head. This will produce a substantial power increase throughout the RPM range. We will not be able to have this completed for the Great American Hill Climb but we will have it ready for the Carnegie Classic in October.
We used the GET RX1 PRO ECU for the flexibility of the system. With its plug and play tuning we could make mapping changes while out at the hills via cell phone. Erik used the MAYA professional software to make two separate maps. One is a very aggressive map and two is a softer map for traction on a more slippery hill. The usability of the wifi tuning was key to making the needed adjustments using a cell phone without riding with a laptop. The difference between the mapping is map two ( the softer map) has 4% more fuel added across the RPM range and 5 degrees less ignition timing below 8800 RPM. We ramp the ignition timing back up from 8800 to 11500, which allows the power curve to be soft on the bottom and still have nice over-rev. This map is designed for the slippery hills. The handlebar switch makes it easy to use and switch between them.
The Xtended brand swingarm extensions bolted right on to our Rockstar Edition. These are necessary for the kind of hills and power this bike is putting out. Keeping the front end down before we put them on was almost impossible. You have three options to choose from. As you pull the wheel back, the traction decreases and gives you more wheel spin. We have been using the 7-inch extension hole but have a 10-inch and a 13-inch option if the traction is too good and we can’t keep the front end down.
Sticker standard sent us over a graphics kit for the event to finish off the build. They fit the bike perfectly and we were very impressed by how they went on, not the usual frustrating bubble and wrinkle cluster we have seen before.
If you liked that build check out this yamaha 450 we did below by clicking here.