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The 1985 RM250F may not look different this year, but suspension and
engine fine tuning have made a w orld of difference for the better.
Ex cell ent mid-range power and su spension makes the new RM a serious
contender in '85, but it needs a bit more power off the bottom.
Test:1
985 Suzuki RM250f
Better than ever?
By Kit Palmer
Not long ago, life was sweet for Suzuki:
Mark Barnett won three-straight 125cc National Championships and a Supercross
Championship; Kent Howerton won the
250cc National Championship
twice in a row; Suzuki maintained it s stranglehold in th e
125cc Motocross World Championship a nd Brad La ck ey became
Am erica's first 500cc World C ha m p ion o n a Suzuki - pretty im p res sive. Suz u ki 's a ro u nd -the- worl d suecess was reflected a t loc al m ot ocrosses
a ro u nd the co u ntry with m an y p ri vateer racers clad in Suz u ki's yellowa nd- bl ue team co lors.
H o w qu ick ly tim es hav e changed.
In 1983, things sta r ted goingsou r [or
Suzuk i w~epJ it: rel eased the RM ·D
models; a lt ho ug h th e 125 was a decent
motocrosser , th e 250 made a giant
step backwards co m pared to th e hot
1982 RM250Z, because it was slo w ·
and didn 't handle. The all-new 1984
RM250 wa s much better th an th e
RM-D , but it still lack ed that need ed '
punch in th e m otor department, especiall y when compar ed to the H onda
CR250 a nd the Yamaha YZ250.
Now we hav e th e 1985 RM 250F,
wh ich looks almost 'id en tica l to th e
.'8 4 d espit e m inor gra p h ic cha nges its interna l ref in ements tha t m a ke th e
new RM a ste p above the '84. Suzu ki
i qT!g~is, · ~'):w ,the; ;~4 c~ ~ ,ca I¥e
cl ose to bein g th e class cha m p . so
th ev focused th ei r a tte nt io n o n the
bike's shortcom i ngs a n d left th e rest
alone.
T he motor needed th e most revisio n , beca use it di d n ' t produce enough
power dow n lo w when exi ting turns,
especia lly tig h t o nes, nor d id th e RM
hav e a su fficie nt a mou nt o f top-end
speed. Bu t it did have potent m id- range,
To improve th e '85 RM m ot o r, Suz u ki
co ncen tra ted o n the already- proven
m id -range a n d made it stronger a nd
bro ader , th en to uc h ed- u p low-end
a nd top -end for smoother acce lera tion.
T his took a co m bi na tio n of tr ick s.
T he fi rs t m ov e was to to ss th e 36 m m
flat- slide ca rb u re to r fo r o ne 2m m
la rger. This a ltera tio n a lo ne gave th e
S uzuki be tte r mid-rang e punch a nd
m o re power o n to p.
T he co n necti ng rod was lengthen ed
8m m to 128mm , a nd a n a l u min u m
spacer plate wa s ins talled between
the bottom o f th e cy li nder a nd th e
en gi ne cases; bore a nd stro ke remain
the sa me a t 70 x 64m m. Th is im p ro ved
th e piston 's leverage on th e cra n k a nd
widened the Suzuk i's powerband, '
mak ing it ea sier to manage. And
p o rts wer e cha nged to g ive th e Suzuki
a bit m ore power throughout th e
powerband.
Besides the 24 6c c e n g i ne being
painted gray (instead of traditional
black ) th e rest remains exactly the
sa m e right down to i-ts three-petal
reed-valve case -ind uc tio n cha m ber,
water- cooling (two radiators ) to its
piston using one ring; however, th e
co m p ressio n ratio is slightlydown to
8,4: I from 8.5: I. The exhaust pipe still
exi ts th e cy lin der through a center
p ort, makes a few bends eventually
Iinding its way a lo n g the right sid e of ' .
the m otorcycle wher e it meets arebuildable a l u m i n u m sile ncer. T o
reach th e si lencer's core, though. four
, po p- ri vets must be drilled o ut w h ich
takes too much time a nd effort: scre ws
{:qlt\ld, ~~ . t,he-j~!= h eas ier , I I
The water pump is connected to
the right o r the cra nkshaft a nd p rotr udes from th e right case cover j us t
i n front of the cl u tc h housin g , w hile
well p rotect ed fro m rocks a n d ot her
bikes (in case of co llis io n ) by th e
ex ha us t pipe,
St u ffed in side th e rel ativel y-small
en gine cases is the same rive-speed
constant-mesh tran smission a nd wet
multi-plate clutch. Alt ho ug h th e in :
ternal gea r ra tios a re not cha nged, th e
rear sp rocke t is o ne to oth smalle r; the
drive ch ain is handled by ei ther a
#520 D,I.D. or a Takasa go (R K) using
116 links. (O u r Suzu ki ca me with a
T akasago .)
.
T he huge a irbox is m ounted en tirely on the ri ght side of th e frame p ro tecting a sin gl e oi led -foa m air filter
from dust a n d g ri t. Like last year,
th ere a re four circ u la r 'indenta tions
o n the o u tsid e o f th e airbo x cover
where ex tra air vents ca n be cu t o u t
for better br eath in g.
Producing juice for a B8EG V spark
plug is Suzuki 's PEl system .
The Suzuki' s frame has a si n g le
downtube fro m th e steeri ng stem th en
splits into a double cradle where th e
exhaust pipe m eet s th e cy linder. Bolted to the bottom of th e frame is an
aluminum brake-pedal guard , as introduced last yea r. The 58 . I-inch
wheelbase, 14.6-inch ground clearance and 33-inch sea t height are unchanged. Rake and trail. wa s slightl y
altered to improve turning quick.
ness; the rake was cha n ged to 30°
from 28°, while th e trail was shortened to 4.3 inches from 4,4 inches.
Even though most riders agreed
the Suzuki's Full-Floater rear suspension was th e best or the bunch last
year, th e Kay aba shock was modified
to improve rear wheel action over the
. sm a ller bumps , especia lly during
braking fo r turn s. Changes included
va lving , compression a nd rebound
d amping revisions as well as a d iffer T
fJ;llr~a~ U?ring s . ' Cl js!:fJfIf.(.Pili , 1)7
.
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