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YAMAHA 90 ENDURO TUNE UP
Following the old idea that if
you have a good thing going, keep
it·up. Yamaha keeps making more
Enduro models. The 90 Enduro is
one that will surprise even the
seasoned rider with its handling
and power. While it is far from
being a 100-mph road machine, it
will pull a good-sized rider across
the desert with amazing ability. In
the hands of some of the
lightweight youngsters that will be
receiving them for Christmas, I
believe we will see a lot of them in
the winner's circle this coming
year. It is still the S1Ime old story;
a machine is only as good as the
care taken of it, so here are a few
hints and tips to help you keep it
in tune so you can get the most
enjoyment out of it.
By Rod Breaker
e-1IoIne
Workshop
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3.1 This is the system for checking the
ignition timing. When the line scribed on the
inner face of the flywheel inspection hole
(L/H arrow) aligns with the stationary pointer
(R!H arrow) the contracts should just break.
If this is checked first, before the contacts are
cleaned o( anything, it will give you an idea
how it has been running.
5.1 Use a 19mm wrench to loosen the center
fixing nul. The flywheel holder is an
adjustable one available from your dealer
through Rocky Cycle Co. for about $4. I f this
type of holder is used, you must take care not
to disturb the setting of the stationary timing
pointer (photo No.3) a.s this would leave you
with no way of determining ignition timing
'without removing the head and installing a
dial indicator.
1 J As ignition timing is one of the most
important items, this should be checked
8.1 If you are using the 'buzz box' or the
ohmmeter type of timLng tester, pull out the
wiring oom from the magneto from under
the gas tank. Disconnect the black wire and
hook the tester onto the magneto side, then
ground the other tester wire and you will be
able to check the timing.
9.1 With the timing device on, rotate the
often. To gain access to the magneto, remove
the th~ee screws (arrows) on the outer cover
behind the shift lever. This cover has a small
section on the rear of it that also covers the
clutch adjuster.
6.1 As most Japanese lightweights use the
same puller, one to fit should not be hard to
come by; this particular one is for the Honda
flywheels but works fine on the enduro. Keep
in mind that the puller is a left·hand thread
into the flywheel, but the T -bar is regular
thread. Make sure the puller is bottomed into
the flywheel before attempting to remove it
to avoid thread damage.
flywheel in the direction of running, as these
two marks are aligned, the tester should show
that the contacts just broke or opened. I f not
right on the money, it must be adjusted,
"close" is not good enough, that only counts
in horseshoes andj1and grenades.
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2.) Remove the spark plug, the head comes
drilled for the installation of a compression
release or an extra plug las shown here). Due
to the angle of the holes, a dial indicator
cannot be used to check the ignition timing
unless the head is removed.
_4.) Insert strip of business card between
contacts and clean them. The other end of
this card was inserted first and shows an
exceptional amount of oil and dirt on the
contacts. If this happens, the flywheel should
be removed and the points and the area
around them cleaned up if reliability is to be
expectl=!d.
7.) Insert a clean rag between the contacts
after the flywheel has been removed and clean
them real good. Also, clean off any oil and
dirt that may be on the entire body of the
contacts. Insert the piece of card again and
check if it comes out dean. When the points
are clean, reinstall the flywheel and set the
contacts to .015 inches.
SACHS 125cc DESERT CHAMPION
Dist. 37 Lightweight
Desert standing
D·ist. 37
Standing
#3 for1971
Eric Jensen
SACHS
#1 for 1971
John Rice
SACHS
Sachs rider Eric Jensen competing in AMA District 37 Desert events
finished third in the Lightweight division and first 125cc. This marks
the first time ever a rider riding a machine of this displacement has
finished in the top five, Eric and Sachs finished nuniber 10 last year.
Again Sachs power, handling and dependability proves itself in rugged
competition. Competing with over 3000 riders in this Division alone, in
many events against as many as'800 riders, Eiric consistently finished in
the first 10 places overall.
Hercules Sachs Dist. Co.
9827 Mason
Chatsworth, Ca. 91311
(213) 882·8272
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10.) As the contact backing plate is at tne
non-adjustable type, the only system you
have for adjusting the timing is to open or
close the point gap. This is done through the
inspection hole with a screwdriver and it must
be checked each time after the contacts are
tightened due to the fact that the gap often
changes when the lock screw is tightened.
Motocross'
11.1 Set the idle air screw all the way to the
bottom and then back it off one and one-half
tu rns. Th is is a good sta ndard sett i ng, you
may get a I ittl better idle by adjusting a
quarter turn either way, but this will usually
suffice.
Need f.af elfra power?
Appearing soon in
winner circ::les
everywhere
'Oownswept Chambers
CZ 250/360 $39.95
Northridge Cycle Products
18854 Muirkirk Dr.
Nntthr.idge.
.91324 (,2131360·7261
c..
