1974 Yamaha TX650A - 6-Page Vintage Motorcycle Road Test Article

Description

1974 Yamaha TX650A - 6-Page Vintage Motorcycle Road Test Article
Original, vintage magazine article
Page Size: Approx. 8" x 11" (21 cm x 28 cm)
Condition: Good
YAMAHA TX650A
Multi-cylinder super-bikes have
evolved into machines that can handle
almost as well as twin cylinder bikes, even
though the multis are wider, heavier, and
have a higher center of gravity. Even so.
heated debates still take place all around
the world as to which design, twin or
multi, is the best.
All the pros and cons of multis have
undoubtedly been considered by Yamaha,
but they have stuck to their twin-cylinder
guns. Instead of taking a big jump into
a three- or four-cylinder touring machine,
they have elected to refine their present
line of twins.
Since its inception in 1970. the Yamaha
TX650 twin has been battling for positive
recognition. It has sold well and has been
one of Yamaha’s most reliable models.
But the original XS-1 had some unusual
handling quirks that have been part of
the bike since the beginning. Some riders
never let the 650’s wiggling and wobbling
bother them: but others, whose level of
tolerance was much lower, confessed to
never feeling quite confident aboard a 650
Yammie.
This years 650. called the TX650A. has
gone through some frame and suspension
changes that are major enough to qualify
the chassis as being all-new. Yamaha
made these changes in an effort to rid the
650 of its unusual handling trails, which,
in turn, would clear up any blemishes on
the bike's reputation. Since the primary
advantage of a twin is its supposedly better
inherent handling, the TX650 would not
be considered a true success until it over-
came its inhibited road behavior.
THE BIKE: Our test bike, the Yamaha
TX650A, uses the same basic powerplant
as last year’s TX650. The narrow, very tall
engine retains its slightly oversquare
75mm bore and 74mm stroke, which give
it a total displacement of 653.8cc. The
compression ratio has been lowered to
8.4:1.
Straight-cut primary gears transmit
power from the 360-degree crankshaft to
the large, multi-plate wet clutch and five
speed gearbox. The gear ratios are close
together and evenly spaced, so no big rpm
drops occur between shifts.
A single-row chain drives the overhead
camshaft, and dual 30.6mm Mikuni-Solex
constant-velocity carburetors supply the
gas mixture to the engine. A two-piece
airbox mounts under the front portion of
the seat and houses a pair of washable,
oiled-foam elements. Another piece of
foam is placed behind each element to
filter out the big pieces. An easy 90-degree
turn of the wing-nut knob on either side
panel gains access to the filters.
The Yamaha uses a conventional bat-
tery/coil ignition system. Dual breaker
points mount at the left end of the over-
head cam. and a massive AC generator
hangs on the left end of the crank.
A panel just in front of the handlebars
holds the speedometer (which reads nearly
five mph fast al 30 and 60), tachometer,
ignition switch and idiot lights.
The 650 uses a double-downtube frame
that has a single, large-diameter backbone.
Heavy bracing and gusseting have been
added to this year’s frame to give it added
strength and permit less frame flexing.
The bike has a sidestand on the left and
a centerstand: it doesn’t take much effort
to get it up on the centerstand, but you
must lean the machine way over to the
right of center to get the sidestand down.
If you have short legs, or if you’re standing
on the left, the bike can easily fall over
on the right side while you're trying to
get the sidestand down.
The TX650A uses alloy rims al both
ends, with a 3.50 x 19 Yokohama ribbed
tire up front, and a 4.00 x 18 Yokohama
universal on the rear. A double-action
hydraulic disc brake slops the front wheel,
and a single-leading shoe drum brake
gives the rear wheel its stopping power.
The front forks allow 4.9 inches of wheel
travel and the five-way adjustable rear
shocks permit 2.8 inches of rear wheel
travel.
Chrome fenders, shocks, exhaust pipes,
and chain guard, contrasting with the
matte black finish of the handlebar
switches and instrument panel, give the
TX650A a neat, modern appearance. The
four-gallon (last year’s was 3.7 gallon)
Cinammon Brown gas lank, side panels,
and headlight also blend in nicely, but the
frame detracts from the bike's otherwise
clean overall appearance. Il has gussets
supporting gussets and frame lubes brac-
ing frame tubes, all held in place by thick,
heavy welds. Other than that, the ma-
chine’s workmanship is well above par,
and all the pieces fit together nicely.
ENGINE AND GEARBOX: The
TX650A has a wide range of usable power
which begins just above idle and lasts to
engine redline at 7500 rpm. It builds
power smoothly and steadily and there is
never a spot in the powerband where the
engine comes on all at once. There aren’t...
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