Yamaha RD400 TZ – The Moto Conspiracy
Written by Martin Hodgson.
It’s hard to deny that Yamaha made some exceptional motorcycles in the ‘70s. Two of those machines are arguably ‘ride before you die’ bikes; namely the insane RD two-strokes and the now legendary TZ racers of ‘King’ Kenny Roberts. So when Dallas bike builder Isiah Booth of The Moto Conspiracy was commissioned to build a raffle bike for the Tenth Annual Dallas Rockers vs Mods gathering, he decided there was no better way to honour these two legends of the ’70s than to combine them into one hell of a machine. To get it done he found a 1977 RD400 and teamed up with Jason Small of Small Time Moto to build a very special race themed machine, nicknamed the ‘Giant Killer.’
The particular RD400 that Isiah found was in fairly poor condition, ok that’s being very kind, it was burnt and badly. Either there had been the kind of fire that occurs when 40-year-old electrics mix with petrol or someone had decided the seat would be a good place for a BBQ and then let the flames spread. But for this build the rear end wasn’t going to be used anyway and the engine itself while still smelling like overcooked steak was structurally intact. Stripped back to its bare bones it was built just the way a race bike should be, from the ground up! The entire tail section was cut off and Isiah fabricated a new rear that would match the TZ body work to be fitted later. The swingarm is new too, taken from an RD350lc, the tubular design brings to the party reduced weight and a monoshock setup. To complete this part of the build a new forward shock mount was then brilliantly fabricated so that the rear shock height can be adjusted if required.
With the basic frame completed it was back to the RD400 motor to fit back in as the heart of the beast and what an engine it is! With the later ’70s also came vehicle emissions tests and the 2 strokes were losing the war, so instead of go out with a whimper like much of its competition Yamaha built the RD400 as a fitting farewell to the blue smokers. A twin cylinder at just 398cc probably doesn’t sound like much to the modern generation, but as a 2 stroke with reed valves and twin Mikuni carbs a leading publication at the time gave this comparison. If you rode the new Honda Hawk 400 four-stroke back-to-back with the Yamaha RD400E, you’d swear that Yamaha‘s two-stroke jet would yank the headlight right out of the Honda. If that’s not enough power Isiah fitted up a set of beautiful period correct expansion chambers for a few extra ponies and an unbelievable sound.
With that snappy power in place where the RD engine seemingly magnifies a quarter-inch turn at the twistgrip to a yards-long leap at the rear wheel Isiah made the very clever decision to fit a steering damper, taken from a YZF- R1. The rest of the front suspension remains relatively standard to keep the period correct look, a TZ replica would be all sorts of wrong with USD forks, but the already good front brakes are improved with a drilled rotor. Out back the new mono-shock assembly features an adjustable shock to allow the bike to be dialled in and the built-in height adjustability means riders of all sizes can tune the handling for just the way they like it. The RD is like its throttle response, a snappy handler, thanks to its short wheel base, short trail and low weight of 170kg fully loaded, but the wheels were far heavier than they should have been. No problem on this machine as they’ve been swapped out for the much lighter RD350 spoked items fitted with Avon rubber.
What really gives this build the TZ element of the merger of two giants is of course that legendary bodywork that became so well-known across the globe with all of King Kenny’s successes. The TZ250 fairing comes from Airtech Streamlining, fitted with a Gustafsson windscreen with Isiah making all the mounts in-house for a picture perfect fit. The legendary long tank and fender come from Meadspeed in the UK and again it was the job of TMC to expertly fit them to the frame, with lots of clever tricks utilised to make it look as if it was always meant to be.
With the bare body fitted up the paint gun was wielded by Jason who laid down the flawless paint in a true Yamaha theme of White and Red before the placement of factory decals give a look that would have been right at home in the race paddock. The final touch is the race number applied to celebrate the years Dallas Rockers vs Mods have been getting together.
Further adding some TZ racing credentials are the beautiful rearsets, adjustable, but mounted in true racer fashion for the rider to get down and stretch out over the tank. While up the front low mounted clips-ons match the theme perfectly and look race tidy with new a single switchblock and just a master cylinder for that minimalist look of the period. The only instrumentation is a tacho that was mounted on in-house fabricated metal work and that’s all the information you need on a tuned RD400, its full concentration or big problems.
So important was concentration and throttle control Cycle Source warned potential RD buyers the RD400 serves notice: be careful and well, or be foolish and sorry. With the bike complete you have a chance to be careful or foolish as raffle tickets are available to win the bike at the Tenth Annual Dallas Rockers vs Mods with a portion of the proceeds going to the Deep Ellum Community Association/Frankie 45 Suicide Prevention.
[Photos by Dat Mai]