Editing Honda CBX250RS

{{Motorcycle
|name             = Honda CBX250RS
|photo            = Honda-cbx250rs--1.JPG
|aka              = 
|manufacturer     = Honda
|parent_company   =
|production       = 1982-
|model_year       =
|predecessor      =
|successor        =
|class            =Standard
|engine           = Four stroke, single cylinder,, DOHC, 4 valve
|bore_stroke      =
|compression      = 10.5:1
|top_speed        = 102 mph
|power            =
|torque           =
|fuel_system      =
|ignition         = CDI
|spark_plug       =
|battery          =
|transmission     = 6 Speed
|frame            =
|suspension       =Front: Telescopic forks <br>
Rear: Swinging arm dual shock
|brakes           =Front: Single 240mm disc 2 [[piston]] [[caliper]] <br>Rear: 180mm drum
|front_tire       = {{tire|90/90 -18}} 
|rear_tire   	  = {{tire|110/90 -18}} 
|rake_trail       =
|wheelbase        = 1355 mm / 53.3 in
|length           =
|width            =
|height           =
|seat_height      =
|dry_weight       = 130 kg / 286.6 lbs
|wet_weight       =
|fuel_capacity    = 12 Liters / 3.1 US gal
|oil_capacity     =
|oil_filter       = K&N KN-112
|recommended_oil=Honda GN4 10W-40
|fuel_consumption =
|turning_radius   =
|related          =
|competition      =
}}

It could reach a top speed of 102 mph.  

==Engine==
The engine was a Air cooled cooled Four stroke, single cylinder,, DOHC, 4 valve. The engine featured a 10.5:1 [[compression ratio]].  

==Chassis==
It came with a 90/90 -18 front [[tire]] and a 110/90 -18 rear tire. Stopping was achieved via Single 240mm disc 2 piston caliper in the front and a 180mm drum in the rear. The front suspension was a  Telescopic forks while the rear was equipped with a Swinging arm dual shock. The CBX250RS was fitted with a 12 Liters / 3.1 US gal fuel tank. The bike weighed just 130 kg / 286.6 lbs. The wheelbase was 1355 mm / 53.3 in long.  
== Photos ==
[[File:Honda-cbx250rs--6.JPG|600px|Honda CBX250RS]]
[[File:Honda-cbx250rs--1.JPG|600px|Honda CBX250RS]]
[[File:Honda-cbx250rs--3.JPG|600px|Honda CBX250RS]]
[[File:Honda-cbx250rs--5.JPG|600px|Honda CBX250RS]]
[[File:Honda-cbx250rs--7.JPG|600px|Honda CBX250RS]]
[[File:Honda-cbx250rs--4.JPG|600px|Honda CBX250RS]]
[[File:Honda-cbx250rs--2.JPG|600px|Honda CBX250RS]]
[[File:Honda-CBX250-83.jpg|600px|Honda CBX250RS]]

== Overview ==
The Honda CBX250RS was a motorcycle first sold by Honda in
May 1983 in Japan as their new 250cc sports bike with a view to replacing
the popular CB250RS. The engine was based on the XR series with particular
links to the XR350 bottom end, including a six speed gearbox and the same
oil pump. The stroke is also the same, but the bore reduced to bring the
capacity down to 249cc. The balance shaft was also discarded, with the
engine instead being rubber mounted. Unlike any other XR engine the top was
given two camshafts. The bike was also equipped with dual carburettors, only
one of which was equipped with a pilot circuit and which open different
amounts depending on how much the throttle is twisted.

The CBX250RS-E was sold in the United Kingdom between 1984 and
1986 where it was a sales flop, being more expensive than the CB250RS which was
still on sale at the time and not being notably better. The release was also
tarnished with stories of bikes wearing out camshafts and rockers very quickly.
In the end an estimated 300 were sold. The model had stronger sales in Japan but
was soon replaced by the GB250 which was styled as a
; this model was successfully sold in Japan until the year 2000
with only minor changes, the most notable of which was the move to using a
single carburetor.





Review


If it wasn't for a healthy Japanese home market in
the 250cc category, we would already have reached the end of the line, since the
reduction in engine capacity allowed to learners effectively wiped the slate
clean in Britain. An enormous choice of model variants has now been reduced,
virtually, to Johnny-boy water cooled buzz-boxes, like the RD250LC and Suzook RG
Gamma, flogged as proddie racers or hooligan tackle, and the oddfellow tested
here.

The reason Honda UK continues to plug away with
developed versions of its four-stroke 250cc single has got absolutely nothing to
do with sentimentality for a dying Dreed. Long after the L-plate raison d'etre
for a quarter-litre class vanished into its legislative sunset, the 250RS kept
on selling to a specific consumer slot: despatch riders. A combination of
four-stroke longevity and reliability, moderately zippy performance, good urban
scratching manners, reasonable fuel economy and a sensible asking price made it
an excellent work tool. It also attracted not a few women, stepping up onto full
tickets but lacking either the confidence or inside leg measurement to cope with
large capacity bikes.

This latest CBX version is a clear development of
earlier RS models in overall function, manners and even appearance; but the
engine, particularly, is almost entirely new. The technology encapsulated in it
has been lifted, apart from the twin overhead camshafts, straight from Honda's
XR range of enduro competition bikes and includes the two most recent
innovations aimed at maximising single cylinder four-stroke performance whilst
removing traditional glitches in throttle response.

The showpiece directed towards extracting more stomp
is Honda's RFVC cylinder head design. This set of initials stands for Radial
Four Valve Combustion. By angling the pairs of intake and exhaust valves
radially, a very shallow combustion chamber is achieved, with the largest
possible valve areas for efficiency and a high compression ratio to up the power
(10.5 to 1 compared to the old RS, which finished up at 9.5 to 1).
Of course, with valve stems sticking out in four different planes, the rocker
gear required to operate them is somewhat complicated.



The cam chain drives an idle shaft geared onto the
two camshafts, incorporating a sub gear to eliminate backlash and minimise
nailbag noises from the whole top end. The cam profiles on each shaft, in their
turn, shove rocker arms and sub-rocker arms about to communicate all that vital
open/close information to the various valves. Sophisticated? Yes, and extremely
well put together. A signal of Honda's departure from the days of cheapskate
throwaway engines is the presence of ball bearings supporting camshafts. The
plain 'holes' masquerading as bearings, with gestural oilways and drilled
straight into a soft alloy head casting, have thankfully become a thing of the
past.

The second clever feature tacked onto the CBX's
cylinder head is the type of carburation. Right back to fond and unrealistic
fantasies of BSA DBD34 Goldies, attempts to drag serious performance out of
single pot four-strokes have always come up against a major problem. High
compression plus good breathing  traditionally by means of an enormous
choke size  provided bags of welly on any given throttle opening, but actually
getting the throttle open tended to gas the motor with a frustrating display of
farts, burps and the very opposite of smooth, instant power delivery. Giving
credit where it's due,

Yamaha circumnavigated this difficulty first on its
XT5 50 trail thumper by the simple solution of having two carburettors, one to
feed each inlet valve, and linked so that one of 'em does the business at low
and mid-range revs and the other comes in to join it when serious grip-twisting
and 'go for it' situations occur. The Yam system uses a slide carb primary and
constant velocity carb secondary set-up, but when Honda gratefully thieved the
idea, it found that a pair of Throttle response is instant and smooth from
tickover to the ten-and-a-half-grand red line.



All good stuff, I'm sure you'll agree, producing
over 30 donkeys instantly on tap in a torquey but nevertheless free-revving
motor. But nothing is perfect. For a reason that must be related to the
advertising/ promotional value of absolute top speed claims on the Jap market,
the CBX lost its place in the Garden of Eden when inscrutable R&D wallies
plotted the gear ratios, subverting the usefulness of the little diamond they'd
just created. Despite a six-speed box, the CBX250RS is outrageously over-geared.

Top gear is barely functional, even as a fuel-saving
overdrive, and, in normal use, kicking up onto that last cog wipes the icing off
the speed cake. Meaningless drag-strip performance claims were borne out by a
particularly educational visit to the MIRA testing facilities with the Honda. On
the way up the motorway, every gust of headwind or the slightest incline meant
cracking down into fifth, and downhill sections barely flagged 90 onto the
clock.

Once onto the mile straights, with the mirrors off
and the slight and wizened form of El Gimpo not so much in the saddle as lying
along the tank, the sun shining and a gentle breeze urging him into to radar
trap, consistent. 102mph readings were obtainable. He clearly sussed, though,
that the most marginal lifting of head, elbow or little pinky would knock as
much as lOmph off terminal speed passing the Willis sunbathing/radar gun
location.
Secondary points of annoyance also exist relating to the CBX engine's behaviour.
The most disturbing of these is as reluctantly critical road testers used to
scribble when fearful of losing advertising revenue  that "some vibration is
apparent".

The CBX250RS appears to lack the
pretty-much-standard contra-rotating balance shafts and relies, instead, on
shearing-type rubber cushion engine mounts to smooth out the vibes. They do
sweet FA. At low revs, a pleasant throb is communicated through the front
portion of the safety seat, straight to a person's privates. (Perhaps this is a
subliminal design feature to tighten Honda's grip on its femal clientele?) With
the motor buzzing, so are the footrests and handlebar. At sustained high speed,
it doesn't take long for dead and white-knuckle syndrome to afflict the pilot
and I, personally, find that unacceptable in a modern  motorcycle. Being
fair to Honda, though, it may have been a fluke characteristic of our early and
probably pre-production test bike.

Transmission remains, incidentally, as lumpy,
snatchy and verging on the naff, as with the old RS. It could do with a far more
efficacious cush drive stuffed into the drive train . ..
That's got to be enough whining and slaggery. Overall, the CBX motor is still
impressive and gives a healthily frugal gas consumption of knocking on 60 miles
to the gallon, ridden with its little throttle on the stop most of the time.
Cruised gently, in a high gear with only one of the carbs being sick into its
inlet tract, 70 or 80mpg could easily be a possibility.



The rolling chassis isn't, generally, that much
different from its predecessor, being a refirement of an already good job. A
steel box-section swingarm now sits inside the main frame triangulation behind
the motor, instead of pivoting outside as on the old RS. The swingarm is painted
black, a merciful retreat from fake alloy toshing jobs and silly trendiness. The
twin shocks have five-position spring preload adjustment but fixed damping, and
are a fraction on the pogo-stickish side. The front suspension now features air
caps on top of fork legs and is substantially improved by the addition of an
alloy fork brace guaranteeing stiffness and pointing straight towards handling
precision.

Detailing is excellent, with only a couple of
omissions relating to my personal prejudices about motorcycling practicality.
The footpegs mount on tasteful cast alloy sub-frames, and the wheels are trad
spoked items with alloy rims. The instrumentation is simple, clear and without
indulgences, except perhaps for the fuel gauge. The powerful halogen headlamp
has reverted to a correct circular shape, reinforcine a no-nonsense image but
clashing somewhat with the boy racer plastic tailpiece used to hide the toolkit
and owner's idiot guide. The bits missing are the chain enclosure to prolong the
sealed O-ringjob's already large slice of longevity into infinity, and the
obvious  a luggage rack. Everybody toting a 'working' motorbike fits one, so
why can't manufacturers include them as designed-in OE features?

On city streets, the CBX's character and deportment
is impeccable. It's got the lightness and 'feel' of a good-handling bike of half
its capacity. It steers like a dream and handles with a stability that belies
its diminutive physical stature. The only time it tries to shake hands with the
devil and weave about is at the very top limit of performance which, given the
over-gearing sitch, doesn't matter that much anyway. The anchors, led by a
vanguard of twin-piston caliper superiority acting onto the single front disc,
are superb. Some bikes are over-braked, some bikes are frighteningly
under-braked; this one is just braked, and that's all you need.

The CBX250RS is a safe and sensible motorcycle at
what could be the end of a classic line. Sure, there's room for improvement, and
if steady consumer demand persists, I'm confident that Honda would get round to
cleaning up the few rough edges  eventually.
And that, really, poses the most awkWard question and highlights the one
critical thing that the Big Aitch almost certainly has got wrong: the price. All
the technological trickery and what must be fairly limited production runs have
resulted in a leap of some four hundred quid over the asking tag on the old
250RS, which is still a current, listed model available in dealers' showrooms.
Such a large slice of gelt could well send prospective punters in other

Source Witch Bike 1984







{|  class="wikitable"
|- 
!Make Model
|Honda CBX 250RS
|- 
!Year
|1982-
|- 
!Engine Type
|Four stroke, single cylinder,, DOHC, 4 valve
|- 
!Displacement
|249 cc / 15.2 cu-in
|- 
!Bore X Stroke
|72 x 61 mm
|- 
!Cooling System
|Air cooled
|- 
!Compression
|10.5:1
|- 
!Induction
|PHO2R Slide valve
|- 
!Ignition
|CDI
|- 
!Starting
|Electric
|- 
!Max Power
|31 hp / 23.1 KW @ 9500 rpm
|- 
!Max Torque
|20 Nm / 14.7 lb-ft @ 9000 rpm
|- 
!Transmission
|6 Speed
|- 
!Final Drive
|Chain
|- 
!Front Suspension
|Telescopic forks
|- 
!Rear Suspension
|Swinging arm dual shock
|- 
!Front Brakes
|Single 240mm disc 2 piston caliper
|- 
!Rear Brakes
|180mm drum
|- 
!Front Tire
|90/90 -18
|- 
!Rear Tire
|110/90 -18
|- 
!Trail
|98 mm / 3.8 in
|- 
!Wheelbase
|1355 mm / 53.3 in
|- 
!Swat Height
|760 mm / 29.9 in
|- 
!Dry Weight
|130 kg / 286.6 lbs
|- 
!Fuel Capacity
|12 Liters / 3.1 US gal
|- 
!Consumption Average
|52 mpg
|- 
!Standing ¼ Mile
|15.8 sec
|- 
!Top Speed
|102 mph

|}

== External Links ==
* https://en.wikipedia.org/wiki/Cafe_racer

[[Category:Honda motorcycles]]