Editing Bimota YB9SRI

{{Infobox Motorcycle
|name             = [[Bimota]] YB9SRI
|image            = [[File:Bimota-yb9sri--1.jpg|frameless|Bimota YB9SRI]]
|aka              = 
|manufacturer     = Bimota
|parent_company   =
|production       = 225 units
|model_year       =
|predecessor      =
|successor        =
|class            =
|engine           = Four stroke, transverse four cylinder, DOHC 4 valves per cylinder.
|bore_stroke      =
|compression      = 12.0:1
|top_speed        = 240.5 km/h / 149.4 mph
|power            =
|torque           =
|fuel_system      =
|ignition         = Integrated with injection using variable spark advance
|spark_plug       =
|battery          =
|transmission     = 6 Speed
|frame            = Two diagonal beams in section bar made of aluminium with internal ribbing. The cylinders are supported by plates bolted to the beams and the swing arm is made of aluminium
|suspension       =Front: 41mm Paioli upside down forks, 22 possible settings in compression and 24 in extension adjustable. <br>
Rear: Paioli monoshock preload, rebound and bump adjustable. It is also possible to adjust the wheelbase by +/- 5 mm.
|brakes           =Front: 2x 320mm discs 4 [[piston]] [[calipers]] <br>Rear: Single 230mm disc 2 piston caliper
|front_tire       = {{tire|120/70 ZR17}} 
|rear_tire   	  = {{tire|180/55 ZR17}} 
|rake_trail       =
|wheelbase        =
|length           =
|width            =
|height           =
|seat_height      =
|dry_weight       = 175 kg / 385.8 lbs.
|wet_weight       =
|fuel_capacity    = 20 Litres / 5.3 US gal.
|oil_capacity     =
|fuel_consumption =
|turning_radius   =
|related          =
|competition      =
}}

It could reach a top speed of 240.5 km/h / 149.4 mph.  

==Engine==
The engine was a Liquid cooled cooled Four stroke, transverse four cylinder, DOHC 4 valves per cylinder.. The engine featured a 12.0:1 [[compression ratio]].  

==Chassis==
It came with a 120/70 ZR17 front [[tire]] and a 180/55 ZR17 rear tire. Stopping was achieved via 2x 320mm discs 4 piston calipers in the front and a Single 230mm disc 2 piston [[caliper]] in the rear. The front suspension was a  41mm Paioli upside down forks, 22 possible settings in compression and 24 in extension adjustable. while the rear was equipped with a Paioli monoshock preload, rebound and bump adjustable. It is also possible to adjust the wheelbase by +/- 5 mm.. The YB9SRI was fitted with a 20 Litres / 5.3 US gal. fuel tank. The bike weighed just 175 kg / 385.8 lbs..  
== Photos ==
[[File:Bimota-yb9sri--1.jpg|600px|Bimota YB9SRI]]
[[File:Bimota-yb9sri--2.jpg|600px|Bimota YB9SRI]]
[[File:Bimota-yb9sri--4.jpg|600px|Bimota YB9SRI]]
[[File:Bimota-yb9sri--3.jpg|600px|Bimota YB9SRI]]
[[File:Bimota-YB9SRI--5.jpg|600px|Bimota YB9SRI]]

== Overview ==


Bimota YB9 SRI
















Given the success of the SR series, development
began on the subsequent SRI model with fuel injection in place of
carburettors. It was essentially the same bike as the SR and can only be
distinguished by small details. They are carbon fibre air intakes, racing
screen and a parking light. The fairing now breaks down into three pieces
for easier dismantling. The Bimota YB9SRi was launched in 1996 to replace the
carburetted YB9SR. The SRi was unique at the time, because it was the only
600cc fuel-injected bike available, and remained so until Triumph's TT600
appeared in 2000. The SRi design was typical of Bimota's efforts at the
time. The Rimini-based firm bought FZR600R and Thundercat engines from
Yamaha, then installed them in the firm's own custom-built supersports
chassis. A racing aluminum frame was festooned with the highest-quality
chassis components available, and the engine fitted with Bimota's own intake
and exhaust systems. The result was an exotic sports machine, at its best on
the track, but also finished to a very high, if occasionally inconsistent,
standard.





Source Injected Aggressor, from RPM magazine,
March 1996 by Alan Cathcart
It was only a matter of time before the modern
era of engine management systems and electronic fuel injection arrived in the
600 supersport arena, and equally inevitable that it would be Bimota that
ushered it in - just as the did a decade ago in the Superbike class.
By launching the latest version of their four
cylinder 600 sports bike, the YB9sri now entering production equipped with their
own EFI developed in conjunction with TDD, as well as with the uprated YZF600R
Yamaha engine from the new Thundercat, Bimota have raised the stakes not just in
the showroom bit also out on the race-track, both in the Supersport 600 category
and the GP world's spin off Thunder bikes class.
Yet in doing so Bimota have also produced a road legal homologation special that
is actually far more user friendly on the street than the carbureted bike it
replaces, thanks to the responsive pick up from the EFI, combined with the extra
power it delivers all the way through the rev range.
Based on a days ride through the Marche hill
country behind Bimota's Rimini base on the first YB9sri off of the production
line, I'd say the 600 street class has a new benchmark - albeit at the premium
price commanded by the Bimota name.
A hand built limited edition, hard noised race replica with the extra
sophistication of EFI the Yb9sri sells in its Italian home market for 25,700,000
lira (£10,700) compared to the carbureted YB9 sister at 22,600,000 Lira (£9,400)
- or a Yamaha Thundercat at not much more than half that. Superbike prices for a
tricked out supersport.
Still, for sure a large production of the first batch of 250 fuel injected
Bimota 600's currently being built will end up on the race tracks of the world,
especially to challenge the dominance of the Ducati 748sp at European
Championship level, where the Desmo Vee Twins made full use if the combined
capacity and weight advantages accorded to them under the rules in effect last
season.



But in 1996, with the minimum 170kg weight limit
the same for all bikes, the Ducati's will not be having it so easy - and of
course Thunder bike racing only permits 600cc fours anyway.
That being the case, Bimota's newly signed Australian works rider Fred Bayens -
fourth in the 1995 Thunder bike series and second in the 1994 European
Supersports Championship - must have a great chance of earning Bimota the GP
circus four stroke crown this season. And after defeating the works Ducati team
to win the 1995 Italian 600 title against all the odds on the factory Bimota YB9
carbie, Michele Malatesta and team mate Miki Gallina (son of former 500cc team
manager Roberto) are bound to be serious contenders for the European Supersports
title with their new fuel injected YB9sri Bimota's. Junior superbike racing?
Sounds like it. Concocting the YB9sri has entailed much more than simply
plugging in a Thundercat engine to replace the old FZR600 motor, and waving a
magic wand over it to add fuel injection. However whilst retaining the same
basic format as the previous 62x49.6mm FZR design (chassis pick ups are the same
as before, for example, unlike on the YZF1000 Thunderace, and the engine
castings unchanged).

The Cat engine used forged pistons instead of cast ones for
improved reliability at high revs, and for the same reason has an all new
crankshaft made of improved material to cure the high rpm crank failures
suffered by some Yamaha Supersport teams at 13,000rpm or more in the past couple
of years. The new crank also has lighter, smaller webs for improved engine
acceleration, which is helped too by a smaller ignition rotor. The result
delivers 100.5bhp at the crank, at 11,500rpm on the Yamaha Thundercat, fitted
with 36mm carbs - whereas without any mechanical changes (same crankshaft, same
12:1 compression ratio etc.) the same engine delivers 106bhp at the crank in the
Bimota guise, running a grand higher at 12,500rpm and translating to 78bhp at
the rear wheel. The difference comes from the TDD/Bimota fuel injection package,
with four 44mm throttle bodies, a single injector per cylinder, and a high
pressure Bosch fuel pump running at 3 bar, all controlled by the ECU mounted on
the rear subframe beneath the seat, via a total of five sensors, monitoring
coolant temperature, ambient air temperature, air pressure, throttle position
and RPM.
Six percent more power at the top end is a hefty improvement that alone would
justify fitting EFI - but the benefits are all the way through the rev range.

There is 51-rear wheel bhp from the injected
motor at just 8,000rpm, compared to 47bhp in the same day dyno testing from a
carbie engine, with corresponding improvements in torque from 56.2Nm to 60.1Nm
at the same revs. This translates to noticeably improved mid range pick up when
you ride the bike - the kind that made me want to compare dyno sheets when I got
back to base. Add in the better response coming off a closed or partially opened
throttle, and the benefits of the EFI start to justify its increased cost -
especially as the YB9sri does not have the same all or nothing delivery as the
previous four cylinder homologation special fitted with TDD/Bimota fuel
injection, the flawed Suzuki engined SB7.
The YB9sri's twin spar chassis, made from Anticordal aircraft alloy, has the
same basic design as the previous carbie's bike, but now has a cast rear frame
brace in front of the back wheel, to which the similarly cast rear upright
incorporating the swing arm pivot is welded.
This makes an even more rigid
structure to cope with the extra grip delivered by the new generation Supersport
race tyres, which ever more closely resemble slicks with a nominal tread pattern
moulded into them.
Those fitted to the street YB9sri as standard are Michelin Hi-Sports - though
fats Fred (Bayens) will use Pirelli's for T Bike racing - mounted on new, very
distinctive cast alloy wheels made to Bimota's design by the same company who
manufacture the wheels fitted to Ferrari and Porsche sports cars. The weigh
exactly the same as the Marchesini's used by Bimota before, but the rear is
actually bigger, at 5.5 instead of 5.0 on the carbie YB9, with the swing arm
widened slightly to accommodate it.
This allows Bimota to fit a hunky 180/55ZR17 rear
tyre instead of a 160/55, still combined with a 120/70 front on a 3.5 wheel as
before. What was this about junior Superbikes? Though chassis geometry is
otherwise unchanged, the 1410 wheelbase and 24-degree head angle with just 95mm
of trail make the YB9sri feel even more like a four stroke 250GP bike than ever
before. The reason is a combination of the rear ride height setting on the bike
as I rode it, and the closely coupled riding position, with the narrow
distinctive styled bodywork (now with a three way split for improved access) and
its trademark Vee neck Bimota screen.
The test bike had just returned from the
Magioe circuit, where the factory development team had set up its handling for
optimum racetrack mode, with a 7mm longer rear shock setting, translating to a
substantially increased rear ride height, compared to street guise. This gives
adequate clearance at racing speeds with the extra grip from the fatter rear
tyre (especially for the freer flowing Bimota exhaust which contributes to the
6% power increase), but at the cost of making the chain rub hard on the swing
arm on the over run, producing an irritating noise as well presumably undue
wear. It also delivers a radical riding position that is more 250GP than
Supersport 600, with a lot of your body weight on your arms and shoulders,
thanks to the low set clip ons which are steeply raked. This makes the YB9sri as
tiring to ride for any length of time on the street as Max Biaggi's 250 Aprilia
is on the track, making each 150 mile thankful from the 20 litre tank a physical
challenge of endurance!
A two hour stint of coping with switch back
mountain roads left me rueing the Max factor with sore wrists, exacerbated by
the outstanding braking delivered by the Brembo 320mm front discs another
powerful weapon in the bikes armoury for Supersport racing. Though more cost
effective steel rotors rather than the more expensive cast iron discs used on
the Brembo equipped Superbikes, these are a big improvement over similar budget
Brembo's I have used recently, with noticeable improved bite, matched with lots
of sensitivity that allows you to stroke off a lot of excess speed, or
alternatively to squeeze hard and get the back wheel waving in the air. And it
does, thanks to an increased front end bias with the higher rear ride height
setting. But the YB9sri mounted street squirrels will need to bullwork their
body into beefcake Bayens mode to prevent the Max factor taking its toll -
either that , or drop the rear ride height a tadge, and go for longer chain life
as well.
But set up as it was for the track (and the
suspension linkage is fully adjustable, so you can tailor the bike for
individual tastes) the Bimota's steering was flawless. You have just got to
think about changing directions and the bike does it - yet without being twitchy
or nervous, and without any straight-line wobbles over rough surfaces, as bikes
with radical race ready geometry have been known to do. It also does not tuck
the front wheel under on tight mountain turns, even trail braking into the apex,
and a key factor in this is the surprising quality of the Paioli forks.
Lets face it until very recently, Paioli suspension was budget class second best
stuff you only used if the price was right. But now they have moved their
development and manufacturing quality up several gears, And Bimota's customers
are the immediate beneficiaries. The 43mm forks on the YB9sri are set up pretty
stiff, so there is not a lot of front end dive under the hard braking those
Brembo's are capable of - but the surprising thing is that they did not chatter
the front wheel even when in the cool winter sunshine, and handled the broken
asphalt of the frost ravaged Marche road really well, ride quality is truly
exceptional for such a short wheelbase bike weighing just 175kg dry.
The Paoli
rear shock - fully adjustable fro pre load, compression and rebound, whereas the
forks come only with rebound adjustment as standard - compression is available
as an option - also coped well with the changes in road surface and handled a
series of whoop-de-doops that have caught out other bikes I have tested over
them, with aplomb. You can actually feel the progressive response of the Bimota
linkage at work as you rise and fall over a series of bumps that any Irish road
race would be proud of - but the same shock setting combines with the fatter
180/55 rear tyre to give excellent Final Final Final Drive out of turns, at the expense of only a
little under steer compared to the narrower 160/55 tyre fitted to the carbureted
YB9. And the bigger tyre definitely did not affect the steering in the form the
bike was set up in - it still flip flops effortlessly through a series of curves
like an Aermacchi fighter aircraft on autopilot, with embarrassing little rider
effort to make it switch direction.


This is a really well balanced and nimble
four cylinder four stroke, with poised yet responsive handling the equal of the
Ducati 748 - and I know of no better compliment in street bike terms. In "Iniezone
Elettronica" guise the YB9sri will be available mainly in the red of the test
bike (yellow continues as an option) which considering it is exactly the same
shade of Italian racing red as a Ducati 916 Superbike is a bit of an irony - but
then Bimota's biggest Supersports rivals are just 100km up the road in Bologna
pinched the YB9's trade mark yellow livery for the 748 Desmo, so maybe they are
just repaying the compliment.
Finish is good, as you have a right to expect at
Bimota price levels, but the fact that the custom made instrument dash is offset
to the left (presumably to make the all important rev counter more visible)
looks plain tacky, worthy of a special builder, and should be redressed pronto.
I would also expect to see a digital temperature gauge on a bike like this, and
a little more padding on that "Road Racer" rear seat would be welcome- though
maybe its board like quality is all part of the Max factor? Footrest position is
great, and the gearchange outstanding, smooth and slick with clutch less upward
gear changes a cinch. But the EFI did not seem to have a choke program in it, so
that firing up the Bimota after a photo session at Riccione promenade in barely
double-digit winter weather left it constantly stalling until the temp needle
crept out of the blue. Solution? Pretend you are fast Fred and blip the throttle
to warm the motor in best paddock posing mode. Still in the natural absence of a
choke knob like the carbie YB9 has in the middle of its fork stem, the EFI needs
to be reprogrammed to compensate.
But once you do get the Bimota's Thundercat engine hot to trot, it will convince
you of the benefits of EFI, with a seamless spread of power delivered in hyper
smooth manner. The YB9sri pulls cleanly from just 2000rpm - even when you gas it
wide open this low down, it does not splutter or snatch, just build revs, slowly
at first, then with noticeably faster pick up from 5300rpm upwards. Then at
7500rpm, engine speed really quickens, with a rush of revs up to the 13000rpm
redline that is not fierce enough to unhook the back wheel even cranked over on
coldish tyres. The YB9sri really motors up high, but it cranks out the power
smoothly as well as smartly.
The EFI delivers the instant response of a set of
flatslides, with out their abruptness. Best of both worlds, really - and well
worth the entrance fee to the Bimota owners club.
But it is not just in comparison to its carbureted counterparts in the
Supersport paddock that the new Bimota has an edge. Well made, with no squeaks
or rattles from the three piece bodywork even on this hard used development
bike, it is definitely a more sophisticated and well rounded bike than the
firstYB9 I rode two years ago. The improved chassis specification delivers
better braking, more tyre and uprated suspension. Taut and tight feeling, the
YB9sri has the responsiveness of a superbike coupled with the nimbleness of a GP
racer, packaged for the street with the allure that only Bimota can deliver to
the four cylinder sportsbike scene. It provides the new standard for others to
aim at in the Supersport 600 class, on road and track alike Fast Fred's a lucky
Ocker!
Source Injected Aggressor, from RPM magazine,
March 1996 by Alan Cathcart




{|  class="wikitable"
|- 
!Make Model
|Bimota YB9 SRI
|- 
!Year
|1996
|- 
!Production
|225 units
|- 
!Engine Type
|Four stroke, transverse four cylinder, DOHC 4 valves per cylinder.
|- 
!Displacement
|599 cc / 36.6 cub. in.
|- 
!Bore X Stroke
|62 x 49.6 mm
|- 
!Compression
|12.0:1
|- 
!Cooling System
|Liquid cooled
|- 
!Induction
|Electronic injection
|- 
!Ignition
|Integrated with injection using variable spark advance
|- 
!Starting
|Electric
|- 
!Max Power
|77.3 kW / 106 hp @ 12500 rpm
|- 
!Max Power Rear Tire
|95.hp @ 12400 rpm
|- 
!Max Torque
|64.3 Nm / 6.6 kgf-m / 47.3 lb-ft. @ 1000 rpm
|- 
!Transmission
|6 Speed
|- 
!Final Drive
|Chain
|- 
!Frame
|Two diagonal beams in section bar made of aluminium with internal ribbing. The cylinders are supported by plates bolted to the beams and the swing arm is made of aluminium
|- 
!Front Suspension
|41mm Paioli upside down forks, 22 possible settings in compression and 24 in extension adjustable.
|- 
!Rear Suspension
|Paioli monoshock preload, rebound and bump adjustable. It is also possible to adjust the wheelbase by +/- 5 mm.
|- 
!Front Brakes
|2x 320mm discs 4 piston calipers
|- 
!Rear Brakes
|Single 230mm disc 2 piston caliper
|- 
!Front Tire
|120/70 ZR17
|- 
!Rear Tire
|180/55 ZR17
|- 
!Dry Weight
|175 kg / 385.8 lbs.
|- 
!Fuel Capacity
|20 Litres / 5.3 US gal.
|- 
!Consumption Average
|5.1 l/100 km / 46.6 mpg
|- 
!Braking 60 - 0 / 100 - 0
|12.9 m / 36.8 m / 46.3 ft / 120.7 ft
|- 
!Standing ¼ Mile
|11.6 sec / 195.5 km/h / 121.5 mph
|- 
!Top Speed
|240.5 km/h / 149.4 mph
|- 
!Road Test
|1996 Motoplus

|}

[[Category:Bimota motorcycles]]