Make/Model Yamaha RD 400
Year 1977
Engine Air cooled, two stroke, parallel twin cylinder, reed-valve torque induction
Capacity 424cc
Bore x Stroke 66 х 62 mm
Compression Ratio 6.2:1
Induction 2x 28mm Mikuni carbs
Ignition / Starting Featherweight Li Battery, dual coils, breaker points / kick
Max Power *no data (40 hp @ 7000 rpm stock)
Max Torque *no data (4.2 kgf-m @ 6500 rpm stock)
Transmission / Drive 6 Speed / chain
Front Suspension Telescopic forks with adjustable preload
Rear Suspension Swing arm, dual Assault shocks
Front Brakes Single drilled 256 mm disc
Rear Brakes Single drilled 256mm disc
Front Tyre 110/90-18 (one size over)
Rear Tyre 120/90-18 (one size over)
Wet-Weight no data (171 kg stock)
Fuel Capacity 13 Litres
Consumption average 43 mpg
Standing ¼ Mile *no data (14.1 sec / 90.1 mph 145 km/h stock)
*some tests could not be performed due to the engine not being broken in
Build Specs:
Engine- Completely rebuilt engine to stock specs. This included a bore to 66mm, with new pistons, rings, pins, and bearings. New gaskets, seals, o-rings and bearings throughout ensure smooth operation and no leaks. The heads and cylinders where thoroughly cleaned by Vapor Blast Solutions here in Santa Fe, then the heads where treated to a nice polish. The cases and cylinders got a fresh coat of black and the fins were sanded to match the wheels.
Frame and Swingarm- Before being powder coated in satin black, the frame had all unnecessary tabs and bracket removed, as well as a new electronics tray to hold the reworked wiring harness and the, now hidden, oil tank which sits neatly tucked under the seat. A new upswept rear hoop was fitted to provide clearance for the rear tire and allow the hidden taillight/brake light/ and turnsignals to be seen when the bike is in operation. The swingarm was treated to a fresh coat of black powder coat as well as new bronze swingarm bushings and new inner bushings.
Suspension- The front forks were rebuilt with new springs from RaceTech and some handy fork caps with built in preload adjusters so you can tune the suspension to the riders needs. New seals and dust boots were installed after the tubes got a good polishing. In the rear we installed new Assault shocks that are .5 in longer than stock. That, coupled with dropping the front .75 in, will put a bit more weight on the front wheel allowing for better handling and control when accelerating out of corners and from stops.
Intake, Exhaust, and Lubrication- The stock Mikuni carburetors were used after a complete teardown and cleaning again by vapor blasting. All brass and gaskets where replaced with new items and adjusted to accommodate new DG performance expansion chambers and pod filters. We stuck with the Yamaha 'Auto Lube' system so you wont have to worry about running any premix, but gave the oil pump a fresh rebuild and new lines and hoses.
Lighting, Controls, and Gauges- Gone are most (or all) of the stock items. We started by replacing the headlight with a newer LED unit that flows more with the angles of the tank and seat, while the lens shape mimics the blocks and knee pads on the tank. We decided to use rubber mounts for the headlight to absorb vibrations rather than make solid brackets so your bulbs last longer. Small but super bright LEDs handle the turn signal duty up front and a combination running light/brake light/ turn signal unit that is neatly hidden under the seat in back. Sitting on a new low rise handlebar are new grips, left and right control switches, and new aluminum clutch and brake levers anodized in black. Aluminum rear sets from KamiKaze Moto were fitted where passenger pegs once lived. With the rearsets in mind, we also reworked the kickstart lever for plenty of space. Handling all the gauge duties is a new programmable Koso unit that is rubber mounted and held in place by a bracket fabricated in house. We also relocated the key switch under the tank to further clean up the cockpit. Powering everything is a new featherweight battery.
Body, Tank, and Seat- We stuck with the original RD tank but had custom blocks and knee pads cut. We like old style decals that you see on many RD's but wanted something unique. The seat was made in house and is a one of a kind fiberglass piece that follows the lines of the headlight and tank. The pad is Ultragel cut to fit the pan and was upolstered by B&M Upholstery in Santa Fe. The benefit of using the gel is that is absorbs vibrations, which is especially good on 2-stroke motorcycles. The front fender has been cut down but left in place to help support the forks, in the rear we removed the stock fender and added an inner fender that matches the front. The fenders were powder coated in satin black to match the frame while the tank, seat, and headlight were treated to a Ford color "Toreador Red'.
Brakes, Wheels, and Tires- We installed new master cylinders as well as new reproduction brake calipers on both the front and rear. We then set the rotors up on a CNC machine to drill and countersink them to help keep brake temperatures down. Lower temps means better stopping power. New custom stainless steel brake lines where also installed to once again aid in stopping power and brake feel. The wheels where coated in black and had the fins sanded to match the cylinders. New modern compound tires complete the package giving great traction in the corners and when stopping.
