Yamaha TZ750 retro racer review

Once upon a time, electronic safety aids, tyres with endless grip and seamless reliability were just a dream, while two-strokes ruled the roost and anyone riding a four-stroke was heckled. Yes, the 1970s were two-stroke years.

The biggest and scariest of the two-stroke arsenal was the Yamaha TZ750. Definitely not a bike made for mere mortals, it revolutionised the way in which racers reached the edge and, for the first time, a proper customer race bike was available to the masses.

In 1974, Yamaha released the first customer TZ700, the ‘A’ model, and from that moment it was the bike of choice, blowing the competition (and a lot of factory racers) into the weeds. Many works riders ended up buying the customer version to race, forgoing factory luxuries from other manufacturers just so they had a better chance of being paid more start money and more prize money. That’s how riders made a living back then, so competitive machinery was paramount.

Barry Ditchburn was one such rider and, when he left the factory Kawasaki squad, he made the sensible choice to link up with Yamaha – if riding a screaming 750cc racing motorcycle that wants to spit you over the bars could ever be called sensible...

In his first event, he blasted past his ex-team mate, South African (and now official MotoGP Legend) Kork Ballington, and from that moment his love affair with the TZ750 has never waned. Until a few years ago Barry was still racing the TZ750, but now he is a fettler for his son Craig on the same machine.

The TZ750 is as straightforward as it gets with an in-line, water-cooled, four-cylinder two-stroke powerplant. In the ‘day’ it pushed out upwards of 120hp, but with Barry’s tuning that’s about 165hp now.

A monoshock rear end with no linkage system takes care of rear suspension duties, while up front there are conventional 41mm forks that carry modern internals. The frame is an exact replica of the original (which Barry has hanging in the shed somewhere) – a twin-cradle steel tube item that is very strong.

Mikuni carburetors fitted with power jets feed the two-stroke mixture through to the pistons and. with the experience of Barry, it may as well be fuel injected it feels that smooth and direct.

The later models reached speeds of up to 180mph, and Don Vesco set a new land speed motorcycle record in 1975 when he used two TZ750 engines crammed into a torpedo-shaped homemade motorcycle. He hit 308.812mph on the ‘Silverbird’, as it was known, without one mechanical failure.

There’s no doubt that tyre technology has gone through the roof in the last 40 years, insofar as grip and the amount of contact patch. Back then, 18-inch was the preferred size front and rear, but Barry has fitted 17-inch to his machine.

There’s no traction control, no quick shifter, no ABS – no anything to save your butt if it all goes wrong and that makes pedalling this bike at speed a real game of chess.

Stopping is still old school with a pair of twin-piston Lockheed calipers up front. The same system that Barry used back in the ’70s adorns the bike now. Surprisingly, the brakes are very good due to the bike’s low weight and modern pad technology.

Phillip Island is the perfect arena to test the TZ750 with its flowing turns and majestic scenery – but to say I was nervous was an understatement. I’ve ridden plenty of exotic motorcycles in my time including an NSR500 V-twin, but that doesn’t prepare you for the hammer blow of the TZ750.

I was surprised initially by the smoothness of the engine. I expected it to rattle and vibrate but this TZ was in perfect balance and harmony. The power feels so much different to your modern-day sportsbike, though: it feels like a 125 under 7000rpm before things start happening in a hurry!

There are no power valves on the TZ750, and that means the barrel tuning plays a big part in the power delivery. Power valves give a broader spread of smoother power by changing the height of the exhaust port, but on the TZ a fixed port means a more aggressive and shorter powerband.

Surprisingly, the handling is very like a modern bike – but so much lighter to change direction. It holds its line well with a decent amount of front-end grip.

On the exit of some faster turns it felt a little too soft and ran ever so slightly wide, but that’s just a matter of playing with the multitude of adjustments on the fully adjustable rear shock.

Braking with the old two-spotters is amazingly good. I was in the fast group at Phillip Island, and when I was in a braking duel with some of the other modern bikes I had no problems matching them. Brake feel is good, too, and that’s important because with virtually no engine braking emanating from the two-stroke you need to be able to feel the edge of front tyre grip.

The lack of engine braking was initially a little disconcerting, and it took me a couple of sessions to get used to almost freewheeling into the corners. It’s not that I haven’t done it in the past, but it’s a rude shock to get used to not having that engine braking force to slow the bike up and load the front tyre in to the turns.

The gearbox is sweet, but as you would expect on any 45-year-old bike care needs to be taken when moving through the cogs. A lot of power is being channelled through the drive train so everything is on the ragged edge; one missed shift could be the end of your day.

The hardest and most difficult part of taming this beast was keeping it in the meat of the powerband, as I had to be one or two gears lower than I would on a four-stroke.

Once I twisted the throttle my knee was dragging the tarmac and the rear wheel was trying to break away with every millimetre of throttle movement.

The electronic tacho is very important on the TZ750 and, while most bikes now have an LCD or TFT dash, this cockpit certainly has a nostalgic feel about it.

Spending time aboard an iconic bike like the TZ750 is something that dreams are made of and, although I grew up after the 750 era, it was still a frightening bike back in the day. I’m not sure there will ever be another bike as ‘alive’ as the TZ750, but one thing’s for sure: next time I’m chatting to an old grey racer that owned one, I will have a deep respect and know why they’re so grey.

Engine: Two-stroke, liquid-cooled in-line four-cylinder
Capacity: 748cc
Bore and stroke: 66mm x 54mm
Transmission: Six speed
Estimated peak power: 140hp (test bike: 165hp)
Carburetors: Four 34mm Mikuni
Frame: Steel tubular cradle type
Front suspension: Varied according to team spec
Rear suspension: Yamaha monoshock, cantilever swingarm (1975 onwards)
Wheels/tyres: 18-inch wheels, 3.25-section front, 3.50 -section rear
Brakes: Twin 300mm front discs, single 220mm rear
Dry weight: 156kg
Estimated top speed: 180mph (depending on gear ratios)