They say necessity is the mother of invention. In the Dirt Bike magazine world, we like to think passion is what fuels an inventor’s mind. Lucky for us, longtime AEO Powersports customer Don Shields rode all the new 450cc machines and couldn’t find one he liked better than his 1999 aluminum-framed CR500AF two-stroke. With Honda’s redesign of the CRF450R in 2017, the passion to build a new-generation CR500AF was there. Don looked to Jeremy and his crew at AEO Powersports to make his dream a reality.
The build started with a high-dollar purchase of a brand-new Honda CRF450R that would immediately get torn down to the frame. With no further use for the four-stroke engine, electronics and exhaust, those items were sold. The engine out of Don’s 1999 pride and joy would provide the power for his new CR500AF—but not before it got a complete overhaul. With the engine turning 18 years old, one side of the cases needed to be replaced.
Once the new case arrived, that and the rest of the engine were sent to Justin at Motowhips for an in-depth cleaning. While at Motowhips, the lower cases received a gloss-black coating on the right side, and the left-hand-side cylinder cases and head were refinished. The carburetor was also refinished on the outside and completely rebuilt on the inside. Internally, all the bearings and seals were replaced using OEM Honda parts. Transmission parts were polished and the cylinder ports got cleaned up a little, but no major grinding was performed. A Boyesen Rad valve was added to improve performance, and Moto Hose red silicone hoses also provided upgrades. The crank was rebuilt with a new rod and then balanced by Crank Works.
With the engine rebuild done, it was time to tackle the CR500AF’s major fabrication. Mike at Edge Finder was the frontman on this part of the build. Obviously, the frame cradle needed to be modified, but Mike didn’t just install a higher Y section and call it a day. He boxed it in below where the expansion chamber goes in between the frame rails, increasing strength and changing the flex characteristics lower on the frame. All-new engine mounts and rear-engine spacers were fabricated to ensure proper alignment of the drive components. Alignment is crucial on this type of build, especially with the amount of horsepower a 500cc two-stroke puts out. If the ratio is off even slightly, the entire build will fail.
Radiator connections on both sides received modifications, and the left-hand-side lower tank was fabricated to clear the FMF expansion chamber. Believe it or not, these were the easier, more straightforward modifications. The more intricate fabrication was configuring a new airboot from the airbox to the carburetor with the correct amount of air volume, and the dual exhaust required clearance on the other side as well. Edgefinder would get some help from EVO Suspension in the form of a hybrid shock that combined two different units into one. This allowed the shock reservoir to be moved onto the right side over the exhaust pipe with enough room for the new dual-silencer system and freeing up enough space on the left-hand side for the intake.
The stock airbox and intake boot was a two-piece molded unit that Mike at Edgefinder would modify by removing the rubber airboot and building a completely custom aluminum version. The last item on our list that required major fabrication was the FMF dual-silencer system. The Edgefinder crew used the existing frame mounts and bent the steel tubing to line up with both FMF Turbinecore 2 aluminum silencers.
Now that the engine and general chassis were taken care of, it was time to wrap up the project. Motowhips came into the picture again, handling the coating of the brake calipers, master cylinders and all suspension components. EVO Suspension valved and resprung both ends of the CR500AF to Don’s specific needs. Galfer brake rotors and steel-braided lines were installed for some additional stopping power. With this build primarily geared towards off-road use, an IMS oversized tank, Cycra Pro Bend handguards, an SXS full-coverage skid plate, Flexx bars, a TM Designs rear chainguide and a Scotts steering stabilizer were must-have items. We went one step further, upgrading the wheels with a set of Talon hubs anodized red, oversized stainless steel spokes and black D.I.D. Dirtstar rims wrapped in Dunlop tires. Instead of traditional tubes, Nitro Mousse foam inserts were used to eliminate any chance of getting a flat tire.
The passion of everyone involved with this build was contagious. This bike has it all—an insane amount of power wrapped in an amazing-looking package. It’s not very often a bike looks so fast that it intimidates people just sitting on the stand.
Getting the AEO Powersports machine started is definitely a process when it’s cold, but once you have the process down and the bike is warmed up, bringing the beast to life is a cakewalk. Riding this machine is a blast! There is no hill it can’t tame, and the power is surprisingly easy to control without vibrating your teeth out. Don is not a small man at 6-foot-4 and 225 pounds, so the EVO suspension setup wasn’t ideal for us, but it still had a balanced feel overall. If Honda made a new CR500 two-stroke and it were this good, people would be lined up around the corner and down the street to buy one. This machine is the first of its kind, but it will definitely not be the last. As a matter of fact, the passion in building this project bike has affected some of our staff members, so don’t be surprised if more CR500 two-stroke builds start popping up.