CARSON BROWN’S 500 TWO-STROKE: PROJECT SPOTLIGHT

MotoFactory · 21 августа, 2024

Carson Brown is incredibly talented and can go fast on just about anything with two wheels and an engine. We all know Carson has a soft spot in his heart for two-strokes of all sizes, but the more cc’s you have, the better things are, right? So, we teamed up with Carson and Riley from BRC Racing Canada to build a race-ready Yamaha YZM500.

THE FOUNDATION

BRC Racing, which is based in Canada, makes a 500cc engine kit that utilizes the YZ250 case-bolt pattern, so it bolts right into a stock 2005–2024 Yamaha YZ250 chassis with no major frame modifications required, and only the relocation of the lower radiator-hose outlets is needed. The Brown family has all kinds of YZ250 engines in different states of disrepair due to Carson’s passion for riding, and that worked out perfectly for this project, because we needed some donor parts. Those parts included a transmission, clutch system, water pump, intake, ignition, kickstart assembly and other miscellaneous parts out of 1999–2023 Yamaha YZ250 engines.

Twisted Development helped dial in the BRC Racing engine, tuning it to get the maximum amount of power out of it.

The BRC YZM500 kit does come unassembled, so if you are more comfortable having BRC Racing assemble the engine, they do offer a service for around $1200 where you can ship them all the YZ250 donor parts needed. They will assemble the engine and ship it back to you ready to drop into your chassis. We had Carson’s dad, Duane Brown, who can assemble just about any two-stroke engine ever made in his sleep, as well as has access to the entire crew at BBR Motorsports, so the engine assembly was no problem for us.

We started off with a slightly used 2024 Yamaha YZ250 chassis in stock form, and once the engine was assembled, the BRC Racing YZM500 installation was really straightforward, and the 500cc engine dropped right into place. The BRC engine definitely takes up more space than the OEM YZ250 version, and there really isn’t any room to spare in the engine compartment. Every inch is utilized, and in some cases, things had to be done in a specific sequence to ensure all the nuts and bolts can be reached. Like we mentioned before, the lower radiator lines had to be rerouted to clear the cylinder and provide room for the power valve to work. The short hose that usually runs between the radiators right above the “Y” in the frame is now a long hose that you see wrapping around the cylinder. All the OEM Yamaha electrical components were used and plugged right in.

With all the needed parts in place, it was time to start testing with Carson and customize the overall YZM500 package to his liking. Like we mentioned before, Carson can go fast on just about any ride, but when he is comfortable on a bike, he can do things that are completely mind-blowing! During testing, the entire YZ250 two-stroke front end was switched out, along with the swingarm and rear linkage all dialed in by Enzo Racing to get the exact feel that Carson wanted. In addition to the BRC engine kit, some additional modifications were made that included a larger carburetor, Hygge handmade exhaust system and, internally, a complete Hinson Billetproof clutch installed.

CARSON’S INSIGHT

Carson had this to say about the build and testing process: “The BRC YZM500 is so much fun to ride! The super-fast, counterbalanced, 500cc two-stroke engine that they developed, along with the YZ250 two-stroke chassis, is a great combination. We made a few tweaks along the way to make it better suited for my style. We used a slightly bigger carburetor for more over-rev that conjoined nicely with a Hygge exhaust expansion chamber, opening up the powerband.

This is one of those bikes that just looks fast just sitting on the stand.

“We used a full Hinson setup for a consistent feel on the clutch. For the chassis, we used a 2012 YZ450F top triple clamp, which let us use a whole YZ-F front end while still keeping the same offset that the 250 two-stroke came with. The YZ-F forks give me a more consistent feel throughout the stroke of the forks, which gave make more stability with the bigger engine.

“For the rear end, we used a YZ-F swingarm and linkage, which slightly lowers the rear end while also slightly lengthening how long the bike is with the swingarm being longer. This gave the bike a more modern linkage and ride-height feel that I prefer. Like I said before, this bike is so much fun to ride, and now that it’s completely dialed in for me, I find it hard to pass by it in the garage to ride something else.”

With that said, we’d argue that this was another successful build. Now, we just have to start brainstorming on what to build next for Carson to ride. Stay tuned for more!