We took in a 1978 Suzuki RM50 as a tired, old dirt-bike that had not ran in many years. The original plastics were extremely faded and cracked. The seat was missing except the pan. Overall, though, it had a lot of potential with nearly all the rest of its original parts, including the exhaust system, intact.
We began by removing the motor and completely disassembling it. Once we got to the crankshaft, we rebuilt the crank and reassembled the bottom end. Next, we bored and honed the cylinder to fit the new piston. We reassembled the top end and put the motor back in the frame. After cleaning the carburetor we were ready to start it. It fired right up and we were pleased with the way it ran.
After establishing that we had a known good running motor, we then looked to focus on the cosmetic side of the project. We removed the motor again and began disassembling parts and separating them into piles to be either powder coated, painted, or replaced entirely.
As it always seems to go, some of the pieces that needed replaced proved difficult to find. Compared to the more popular JR50 and RM80 models, the RM50 was relatively rare and produced for only a few years, which when coupled with age, almost always translates into limited availability of parts.
The original front rim was far too rusty to be saved and we were thankful to secure a new replacement. The front forks were corroded beyond use and unavailable elsewhere so we had custom ones made by Frank’s Forks out of Hernando, MS.
We’d also planned on replacing the fenders and the seat, but could not locate ones that were in better shape than the ones already on the bike, so we changed course a bit and worked with what we had. We had a custom seat pan made by J.B. Kepple Sheet Metal Works in Mt. Vernon, OH and cover made for the bike by JK Auto Upholstery in Heath, OH. We took the original plastics and gas tank to Tim Compton in Ashley, OH and had them painted.
After the frame and swingarm were freshly powder coated black, we replaced the steering head bearings, wheel bearings, and bolts in the frame and began the reassembly process. This included lacing and truing a new set of wheels with new spokes and fitting them with IRC Mini Motocross tires.
As anticipated, assembly went smoothly as this is a very simple bike. We cleaned and painted various parts such as the foot pegs and the exhaust pipe. We also painted the shock springs Suzuki yellow to match the rest of the bike. Disappointingly, we were unable to source original gas tank decals, but think it still looks fantastic without them.
Once fully assembled, we test rode (video here) and were thrilled with how well it ran!
