Yamaha TT 600
Yamaha TT 600N
Air cooled, four stroke, single cylinder, SOHC, 4 Valve per cylinder.
Bore x Stroke
95 x 84 mm
27mm Dual stage Teikei Y27PVX1
CDI / kick
NGK DPR7EA or DP7EA
45 hp 34 kW @ 6500 rpm
50 Nm 4.7 kgf-m @ 5500 rpm
5 Speed / chain
1st 30/13 (2.367) 2nd 27/17(1.588)
3rd 24/20 (1.200) 4th 21/22 (0.954)
5th 21/27 (0.777)
43mm Telescopic forks, 300mm wheel travel
Monocross single shock 20-way compression,
reload and rebound adjustment., 270mm wheel travel
1485mm / 58.5 in.
935mm / 36.8 in.
300mm / 11.8 in.
28° / 130mm
/ 2.9 gal
THE four-stroke off road market has always been limited to a certain segment
of eccentrics. Two-strokes, by virtue of their inherent design characteristics,
perform and handle better — and are often cheaper. Logically, the two-stroke
should be the serious offroad rider's choice.
In fact up to now, the big bore four-stroke has had very little going for it
except the fact that it is, well... a four-stroke. It makes a satisfying noise
and somehow reminds us of those tales about Velo-cettes and Manx Nortons being
the only real bikes ever built on God's Earth.
A four-stroke, like a slice of quiche, has always been to some men, A Real
Man's Motorcycle. As a dirt bike, not always very practical, hardly ever the
quickest, but nevertheless a proper bike.
The XT 500 and its more competition-orientated brother, the TT 500, were
proper bikes, lusty four-strokes with a following that ranged from Durban
potheads to desert adventurers. But on the bottom line, when it came to
competition use, nobody in their right minds would enter an old XT or TT in an
enduro. At least not in standard form — they were too slow, much too heavy and
handled like pigs.
In contrast Yamaha's 1983 TT 600 is something of a revelation. It replaces its predecessor so completely
and with so much flair, that one wonders whether there wasn't an intermediate
model that we missed out somewhere along the line.
The new TT 600 is a street scrambler in the sense that it is sold in a form
that barely covers most municipalities' and provincial authorities' requirements
for street-legal machines. What I am saying is that it is conceivable that you
could ride it to work in the mornings and not get hassled by a man in khaki.
But it is far more than a street scrambler because it's very evident that
this bike is not a compromise. Let's look at it: the TT 600 engine is simply an enlarged version of the TT 500 engine which made its
first appearance in this country last year, and soon gained a reputation for
being a fast, reliable street scrambler.
Bore and stroke are now 95 x 84 mm to give a displacement of 595 cm3.
The inherent vibration of the large capacity, big bore single is damped out by a
contra-rotating balance shaft geared directly to the crankshaft and mounted just
behind it. A single overhead camshaft is driven from the crank via a Hy-Vo chain
with an automatic tensioner. This operates four valves.
Like Honda, Yamaha have gone the four-valve route for four-stroke dirt bikes
because this system allows a greater port area without af-fecting combustion
chamber shape, and the valve springs can individually deal with less
reciprocating mass — making the mill more reliable at peak revs.
Ignition is maintenance-free capacitor discharge with a small 12-volt battery
to deal with the street legal items.
The fuel-feed system, like the XT 500, consists of the Yamaha patented Duo
Intake setup with a twin barrel carburettor (1 mm larger than theXT550's).
The bike has an aluminium kick-start, and starting is reasonably easy for a
single of more than half litre displacement — mainly because of the
cable-operated, automatic decompression facility which comes into operation when
the engine is kicked over.
Like the old big Yam singles, this one has a dry sump lubrication, but the TT
600 doesn't carry its oil in its spine: a new oil tank has been positioned above
the swingarm pivot, and this gets the centre of gravity as low as possible.
The bike's running gear is more of an indication of its no-compromise
character than the engine. The frame is made from high-tensile steel and
the swingarm is extruded aluminium.
The rear-end consists of the new rising rate Yamaha Monocross linkage
suspension, with the single shock positioned low and leaning slightly forward
from the end of the swingarm. Compression damping and preload are adjustable,
and the setup has a remote reservoir.
The front-end is really out of the top draw: 43 mm Showa fork tubes with
aluminium sliders and 300 mm of travel! The front brake, although not a disc, is
an exceptionally effective twin-leading shoe stopper.
Overall finish is good. The TT 600 is offered almost in IT enduro spec. It
has a plastic fuel tank, tool bag with an impressive set of tools, quick-release
axles with snailcam adjusters, side-pull throttle, alloy rims with strong spokes
and an O-ring chain. Tyres are 3.00 21 and 150/80 18 IRCs which work well.
It is one of those dirt bikes that feels right, from the time you get on, to
when you start takin skills), it's a bike that can be ridden easily by both the novice dirt rider
and a veteran expert.
The TT is first and foremost a big bore four-stroke, and this is, perhaps
it's most endearing quality. But the fact that for the first time we are offered
a four-stroke with such a big engine along with such superb chassis and
suspension components, puts this bike into a class all of its own.
For a big bike, it turns fairly easily and although it's not the best for
really tight terrains, the wide, wide power band makes riding in most situations
a giggle. This sucker has a Kalahari Desert-full of torque: 4,7 kg/m at 5 500
revs/min! It likes lugging over large boulders and that forgiving engine doesn't
falter up the steepest of inclines.
Lots has been written about four-stroke power, but in reality a big
two-stroke will go up a hill better than a four-stroke. However, I think that
the TT 600 could be in with the large strokers when it comes to hills.
However, it's over open territory that the new TT really comes into its own.
The quality suspension soaks up high speed bumps and the monolithic powerband
can be used to slide the bike safely and predictably through fast turns. It's also got the brakes to match its top-end
This bike's a winner in my opinion one of the best all-round dirtbikes on
the market at the moment, and definitely one of those that are the most fun to
ride on your favourite trail!
source BIKE & TRACK 1983
At 595cc's it has 6% more displacement than the XT550, yet
weighs 8% less. In fact, the entire bike, with its totally redesigned chassis,
is 10 kilogrammes lighter than the XT550.
To deliver all the power and torque, undiluted to the ground,
the TT600 is equipped with the latest Monocross rear suspension, taken directly
from our YZ motocross racers.
The monoshock unit is fully adjustable for rebound damping and
pre-load. It's also smaller, lighter, more compact and sits lower in the frame.
This, combined with a lower, more
centralised oil tank, contributes to an exceptionally low
centre of gravity and an appreciable improvement in handling.
Of course, this remarkable assembliage of unequalled 4-stroke
power, state-of-the-art chassis and YZ suspension wouldn't be complete without a
front end to match. In this case, air-adjustable forks with huge 43mm tubes and
no less than 300mm of travel.
Add to all that some of the competition-proven features of our
IT enduro racers— quick-release axles, snail-cam chain adjusters, all ADR
lighting and instrumentation requirements, tubular engine guards and a very
generous tool bag—and what you've got is the first 4-stroke dirt machine that's
more than equal to the rigors of enduro, cross-country, desert and 4-stroke
motocross racing. Or the pleasures of a weekend of backWoods biking.
The TT600's motocross-proven Monocross rear suspension is a true
"rising-rate" suspension. Which means that as the rear wheel begins to move
upward, the suspension begins to stiffen. The farther the wheel travels, the
stiffer both spring rate and shock damping become. The redesigned pivot and
strut system allow the reservoired gas/oil shock absorber to sit lower, lowering
the centre of gravity.
TT600ENGINE WITH YDIS
The TT600's powerplant is one of a kind. It not only has four valves and a
dual exhaust system, it has a dual intake system, too.
To take full advantage of the four-valve set-up, our Yamaha Duo Intake System
actually utilises two separate carburettors, a primary slide-valve unit and a
secondary butterfly-valve unit. That makes for a combined intake area 20%
greater than that of a standard single carb.
source Yamaha TT600 brochure
Though virtually unchanged for the last two years,
the Yamaha TT600 has something going for it: Basically, it responds to simple
modifications better than any other big four-stroke.
Slap a pipe and a carb on a Honda and you don't get
much out of it. Do the same thing to a TT600 and you get an increase in
performance that surprises and delights you.
This makes you wonder about two things: Firstly, you tend to be grateful about
the low-cost improvements, and secondly, you wonder why-oh-why did they ever
strangle the stock setup so much in the first place? RIDING IT STOCK
That's the first impression you get. The power is
decent, with enough down low and mid-range to deliver a certain amount of
satisfaction, but there's no real gut-wrenching snap to write home to Mom about.
You just want more out of the massive 600cc four-stroke engine. You surely
expect more. Still, one cannot snivel about the sheer acceleration of the TT600,
as it will normally pull an XR500 in a basic drag race.
The bike is heavy... too heavy, according to the
gastronomically correct DB scales, which indicate 280 pounds, with no gas in the
2.9-gallon tank. This places it right in the ballpark with the other big
four-strokes in its class.
The Can-Am Sonic weighs 275.5 pounds; the Honda XR500 is the same; and the KTM
504 is heftier at 286.5 pounds. All of them, in our opinion, are 25 to 30 pounds
too heavy. The four-speed Husky four-stroke, on the other hand, is slightly
under 255 pounds, with no gas in its tank.
When you ride the 280-pound Yamaha, you'll be
horsing around with nearly 300 pounds of bike and fuel/oil. You feel it on the
rough stuff and when you land from jumps, but when doing what the TT600 does
best, you completely forget about the weight.
What the TT600 does do best is slide like a fool on flat, twisty fire roads. The
steering is decent and the rear end can be cranked out with the power on and
left there as the rider does his best imitation of a flat-tracker.
Over medium-rough whoops and bumps, the suspension
is not bad. It soaks up the medium-sized and small bumps just fine. It'll even
take serious bumps all right if you don't pound them with too much speed. But
when the TT600 is forced to slam through the serious grinders, the shortcomings
of the forks and shock show their glitches.
The forks will clank metal to metal, even with the maximum safe oil level.
Heavier springs (optional Yamaha parts) are the answer. You lose some of the
suppleness with heavier springs, but if you insist on pushing the TT600 hard,
they're a must.
At the rear, a heavier spring is also needed.
Luckily, a huge selection of YZ springs
(and even shocks) will fit right on the TT600. You can dial that rear end in
with patience and the right spring.
Our suggestion would be to leave the stock suspension on the bike for most
trail-riding conditions or woods work. For desert enduros or desert
riding/racing, you should go for the heavier suspenders.
We found the TT600 a reasonable bike to start—for a big four-stroke. More often
than not, it would bang over within three kicks, hot or cold. Every once in a
while it would get stubborn and require a dozen boots, but this was not the
At lower trailriding speeds, the TT600 is plenty smooth to make riding easy.
There's no jerking around from weird power pulses.
Plenty of mid-range lets the rider shift early and
the TT600 does not protest when forced to rev out. We spent some time playing
around climbing hills with the big white TT600, and as long as there was
reasonable traction, it comfortably conquered anything we tried.
On soft sand hills, the rear tire tended to dig in much easier than we would
have liked. A heftier slab of rubber (one of the big footprint Metzelers) would
really help in the loose stuff.
Shifting was notchy at first but loosened up with
time and a few oil changes.
The low saddle height was appreciated by shorter riders. Brakes were super, with
the front stopper being almost as strong as a disc.
Nice touches include a tool bag, odometer and hand protectors. Bash bars help
keep rocks away from the cases.
Although not an amazing four-stroke bristling with
technology, and more than a bit heavy, the Yamaha has no real serious flaws. The
engine is stone-ax reliable, seems to have a bulletproof clutch that will take
all manner of abuse, and is a relatively easy bike to start and ride.
No magic. No finesse. Just a rock-solid, decent bike with a lot of potential...
one that you can beat on for a long time without worrying about.
Source Dirt Rider 1984