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Honda 2008 Fireblade Technotes from Honda Online...

Discussion in 'Technical and Troubleshooting Torque' started by toast, Jun 20, 2008.

  1. straight from honda online [by] a tech:

    The all-new 2008 CBR1000RR proves that less is more. This machine is smaller, more compact and lighter than its predecessor while also being faster and more nimble! It pays homage to its heritage while breaking new ground in the literbike class, where it holds stunning advantages in power-to-weight ratio, acceleration, and handling -- teamed with open-class horsepower -- all in a compact package that's the lightest in its class.

    From a technical point of view, there are numerous changes on the 2008 CBR1000RR. Here are some of the highlights:

    An all new 999 cc inline 4-cylinder engine with an Idle Air Control Valve, Ignition Interrupt Control System, and slipper clutch; low-mount exhaust system design; four-piece Fine Die-Cast frame; twin-tunnel ram air induction; aluminum gull wing swing arm; monoblock front brake calipers; Honda Electronic Steering Damper and much more.

    The new engine is lighter and more compact than the previous engine by more than 5 pounds, and it stands a full 15 millimeters shorter. To accomplish this, the exhaust valves were shortened three millimeters so the camshaft could be placed lower in the cylinder head. The engine also has lightweight, larger-diameter 30.5 millimeter titanium intake valves. There's also a new, separate cylinder block with lighter, sleeveless Nikasil-coated cylinders. And lightweight larger-bore 76 millimeter forged pistons feature a low-friction molybdenum coating.

    Let's take a closer look.

    This engine has new, lighter camshafts that are manufactured using a new chilled thin-wall ductile steel casting process that makes it possible to reduce the camshaft wall thickness from 4 millimeters to 2.5 millimeters, saving 1.1 pounds -- all while maintaining the same levels of strength and durability. For further weight savings and quicker, higher-revving performance, new, larger-diameter titanium intake valves fitted with double valve springs replace the steel valves used in the previous engine. Honda is also employing a new process to "smooth" the intake tract in the cylinder head. The ports are filled with a special abrasive material, then placed on a vibration table, and the shaking action creates the right texture for optimum airflow conditions.

    Here's something you need to be aware of: The 2008 CBR1000RR uses the newer KT7-013 valve shims for the intake valves that are made of a different material. If you use the older KT7-000 valve shims when servicing this engine, those shims will prematurely wear the top of the titanium intake valve stems, increasing valve clearance. A good idea is to have two shim sets in your service department, one for your existing valve shims, and the other labeled "013" for these new shims. That will help prevent intermixing the shims because they look identical.

    A side note: removing the cylinder head cover on the CBR1000RR is just like the procedure for the CBR600RR except you have to remove the radiator, then lift the cylinder head cover up, and roll it down over the front of the engine to remove it.

    While the 2007 CBR1000RR had an integrated, one-piece cylinder block and crankcase, the new 2008 engine has a separate cylinder block that allowed the cylinder sleeves to be replaced with a super-tough Nikasil coating that is applied directly to the cylinder walls. Eliminating the cylinder sleeves permitted the bores to be increased from 75 to 76 millimeters, reducing cylinder spacing from 6 to 5 millimeters, while maintaining the same cylinder pitch and overall cylinder width as before. Effective cylinder weight was also reduced, while displacement was increased from 998 cc to 999.8 cc.

    With the compact design of this engine, if you have to disassemble the top end, the engine has to be removed from the frame and the cases split because once the cylinders are off, there is not enough room to get a ring compressor in between the cases and the cylinder.

    You should also be aware that all of the cylinder studs have a hex-machined end. Tightening the cylinder head nuts includes a step of tightening the studs into the crankcase. The studs require an angle torque gauge and the plastic region tightening method to torque them to the correct pressure - which is 25 N•m plus 135 degrees.
    The bottom line, remember that once the cylinders come off, you are going to have to separate the cases to reassemble the engine.

    Now let's look at the pistons:
    Even though they are 1 millimeter larger in diameter, these forged aluminum pistons are the same weight as the pistons they replace.
    The pistons are connected to new, high-precision cold-forged connecting rods. These rods feature smaller dimensions and tighter tolerances for significantly reduced reciprocating weight while maintaining the same strength and rigidity of the hot-forged rods in the 2007 engine.
    When the engine is mounted in the frame, you cannot see the cam sprocket timing marks because they are obstructed by the frame.
    An inside punch mark has been placed on the cam sprocket so you can check the setting without removing the engine.

    To reduce the width and weight of this engine, it features a new Hall Integrated Circuit, or IC cam position sensor. On the previous model, this sensor was an electromagnetic design, which meant the air gap of the sensor was critical. On the new model, the sensor is extremely accurate, and it can operate with a wider air gap, which allowed it to be moved to the cylinder head cover.

    This engine has an Idle Air Control Valve, or IACV, similar to the CBR600RR. This system allows a measured amount of intake air to bypass the throttle bodies' closed butterfly valves. This IACV circuit gives a smoother transition of power as the throttle is opened at high rpm, such as when exiting a corner.

    At the same time that the IACV is smoothing power delivery as the throttle is opened, the Ignition Interrupt Control is reducing the effects of gear backlash. This is the first Honda engine to incorporate an Ignition Interruption Control system.

    Here's how it works:
    The ECM uses input from the crankshaft position sensor and the vehicle speed sensor to check for gear backlash. Whenever the crank speed exceeds the rear wheel speed, the ignition is cut for a fraction of a second to allow the wheel to catch up to the engine. All this begins and ends within milliseconds, it simply feels as though throttle applications with the CBR1000RR occur with remarkable smoothness.

    Honda's engineers created a unique assist-slipper clutch that acts in concert with the IACV and Ignition Interrupt Control systems to further smooth OFF-ON throttle transitions. This represents the first use of a slipper clutch in a production Honda. Plus, this design is exclusive to Honda. It has a mechanical spring-assist system built into the clutch to ensure clutch lockup while reducing the pull effort required at the lever.

    The purpose of a slipper clutch is to have more control over deceleration torque - also known as "back torque" -- on the rear wheel during aggressive braking, thereby allowing engine braking to slow the bike without causing the rear wheel to chatter.

    Here's how it works:
    At the engagement area between the clutch center and clutch pressure plate, radiused surfaces act as cams to adjust forces incrementally.
    Under heavy deceleration, when back torque from the slowing rear wheel grows greater than the slipper clutch capacity, clutch slip occurs to relieve that excess portion of the engine-braking action and minimize rear-wheel chatter.

    A common shortcoming with conventional slipper clutch designs is the large amount of pressure required to force the clutch plates back together once no more slip is required. Other companies counteract that issue by using stiff clutch springs which can create uncomfortably stiff clutch action.

    Honda engineers came up with a more viable solution: On the CBR1000RR, when forces generated under acceleration act on the clutch center and pressure plate in the driving mode, another set of cammed surfaces act in the opposite direction to automatically increase the amount of pressure generated on the clutch stack by the clutch pressure plate.

    It's actually like a reverse slipper clutch. As a result, the CBR1000RR uses lighter clutch springs than those in a standard slipper clutch, yet clutch lockup occurs quickly, securely, and reliably.

    This design allows the rider to enjoy a reduction in clutch lever load for a lighter pull at the clutch lever. And thanks to this more efficient design, the CBR1000RR uses a cable actuation system, which is lighter than a hydraulic clutch and the cable provides a direct mechanical link for better "feel" at the clutch lever.

    There are a few key points to be aware of when servicing this slipper clutch: First, before you remove the clutch cover, remove the dipstick. Second, whenever you take off the clutch cover, remove this starter idler gear. If the crankshaft is turned with the side cover off, the crankcase will break.

    As you can see in this illustration, there are three different clutch discs - A, B, and C. Discs A and C have different friction material than B, so they are compatible with the aluminum pressure plate, while the B discs work against the steel clutch plates. You'll also notice that Disc A has a larger inside diameter than the other discs, to provide space for the anti-judder spring.

    As the clutch plates wear, the total thickness of the discs and plates changes affecting the clutch spring force. When it becomes too thin, it's time to replace the clutch pack, which is why this clutch is offered as a set of discs and plates, as well as separate parts.

    When you are assembling the clutch, you'll temporarily insert three 6 millimeter bolts to connect the two parts of the clutch center, making sure you have the A, B and C discs in the proper locations. Then, slip this assembly onto the mainshaft, install the attaching nut, and remove the three bolts. And use this special tool to hold the clutch while you tighten the nut that holds the clutch center to the mainshaft. Attach the clutch lifter plate and lifter piece. When refilling the engine oil, only use approved Pro-Honda or equivalent oil, as other oils may contain graphite and molybdenum, which could damage this clutch.

    To help maintain a consistent temperature range, the CBR1000RR has two cooling fans, with the right fan being larger than the left fan. Both fans are controlled by the ECM, with the right fan coming on initially. Then the left fan is engaged as the engine temperature rises. Under some instances, even when the engine is not too hot, the fans may switch on based on input from the ECM. When the fuel gets down to the reserve level of point nine gallons of fuel, the low fuel indicator light will illuminate. At the same time the lower segment of the multi-function display automatically changes to show the consumption of the remaining fuel.

    The exhaust system is now positioned almost entirely beneath the engine to increase mass centralization in keeping with the MotoGP doctrine of Honda's current RC212V. With this low-mount exhaust, roll inertia is reduced by 13 percent and yaw inertia reduced by 10 percent.

    To maintain top performance while reducing noise output, the large, triangular-section secondary muffler features a three-chamber configuration. At low engine speeds this valve is closed and exhaust escapes from the smaller outlet only. As engine speed rises, this valve is opened via a cable by an electronically controlled motor.

    This Electronic Variable Valve is programmed to open at different engine speeds from 3,900 to 5,600 rpm in each gear. This opens the larger second outlet. As engine speed increases to 7000 rpm, a pressure activated valve opens between the second and third chambers of the muffler. This creates a more direct path for the exhaust gases for improved performance in the mid-to-upper rev range.

    The CBR has a new, four-piece Fine Die-Cast frame. This bike features a centrally located fuel tank that increases mass centralization and allows for a thinner, more compact frame. The frame's four sections include a large steering head casting, two side spars with large holes for the straight shot ram air ducts, and a single large U-shaped rear pivot mount section. This section wraps under the rear of the engine to surround the swing arm pivot and further ensure the frame's exceptionally rigid form.
    All sections are hollow-formed with approximately the same 2.5 millimeter wall thicknesses found in the 2007 CBR1000RR. But the new frame is significantly stronger, with lateral rigidity increased 13 percent, torsional rigidity up 40 percent, and vertical rigidity up 30 percent.

    With the new frame comes a new engine mount. This design features a new, expanding collar that pulls in tight against the engine so that when you tighten it, it splays and "pinches" the frame. This design contributes to the overall rigidity, which in turn, enhances the handling. When designing the new frame, the rider's seating position has been reconfigured so the rider sits closer to the steering head. And the swingarm pivot point has been moved forward by 10 millimeters, so the distance from the pivot to the steering head shortens up the same amount, and the rider moves with it. In addition, the footpegs now rest 20 millimeters farther forward and 10 millimeters lower, and the handlebars were moved 2 millimeters forward and up 6 millimeters for a more comfortable upright position.

    To provide clearance for the low-mount exhaust system, the CBR's hybrid aluminum swing arm was redesigned with a new gull-wing shape for the pressed aluminum right side member. This new swing arm is 12 millimeters longer than the one it replaces.

    Now let's turn our attention to the brakes:
    The radial-mount front disc brakes feature new monoblock four piston brake calipers that are stronger and lighter. Each one is 4.4 ounces lighter, while being more rigid. Inside, chrome-plated aluminum brake pistons replace heavier steel units for an impressive total of 15 ounces of reduced unsprung weight in the calipers alone. The front brake rotors were lightened with new six-point floating mounts that replace the current ten-point units. The drilled rotor hole pattern has also been changed to a design that debuted on Honda's Suzuka 8 Hour Endurance racers. Plus, the front brake lines are made of a new material that's narrower and lighter. In addition, the brake lever ratio has been modified to increase braking performance while delivering a livelier, more responsive feel.

    Now let's look at the forks:
    The forks have revised springing and damping rates and the span between the fork tubes has been reduced by 10 millimeters. Fork offset is increased by 2.5 millimeters. Together, this provides quicker response to steering inputs. The front axle holders are a more centered design that increases rigidity while minimizing unsprung weight.

    The CBR1000RR features the next generation Honda Electronic Steering Damper, or HESD for short. It's lighter and more compact than its predecessors. This damper tucks under the fuel tank cover and mounts to the frame behind the steering head. It connects to the upper triple clamp via an articulating arm that moves the unit's damping vane within its oil chamber.

    If you have to remove the steering damper, loosen the linkage at the triple clamp, not the damper. The position of this arm on the damper shaft is critical to align the linkage. In both front and rear suspension systems, new spring rates and damping rates deliver optimum performance from the CBR1000RR.

    If you have to remove the windscreen, start by removing the nuts and pull the rearview mirror mounting studs out of the fairing, leaving the wire harness connected. Then, remove the bolts, plastic washers, rubber washers, windscreen and nuts. Be careful not to damage the tabs. Also, make sure you stack the washers in the correct order as shown here.
    Up front, a pair of performance-enhancing ram air intake tracts are smoothly integrated into the front cowl to direct a steady stream of cool, dense air straight to the airbox. To minimize noise and maximize low end and midrange performance, both ports are equipped with resonator butterfly valves that remain closed at engine speeds below 6,000 rpm, then automatically open at higher engine speeds to increase airflow.

    The turn indicators are now integrated into the upper portion of the rearview mirrors. Integrating the turn signals into the folding mirrors enhances aerodynamics by contributing to the fairing's simple, efficient, compact form and reduced coefficient of drag. If you have to replace a bulb on the front turn signals, be careful when separating the turn signal assembly from the mirror so you don't damage the tabs.

    The CBR also has a lightweight aluminum sidestand, shaving off a few more ounces. Even the battery was scrutinized and minimized on the CBR1000RR. A typical 10 amp hour battery can weigh close to 7 pounds and takes up a considerable amount of space. On this bike, the engine's starter ratio and starter motor characteristics were revised to produce the same strong engine-turning torque but with less electrical current draw. These changes made it possible to achieve the same number of repeated starts -- and quicker starts -- with less battery output. So the CBR1000RR carries a battery that's smaller, and this 7 amp hour battery saves more than 2 pounds over a conventional setup.

    Honda's engineers have again extended an innovative family heritage reengineering even the smallest details to redefine the state of the supersport art. By reducing the size and weight of the CBR1000RR to new levels, Honda has integrated power and handling in a way that establishes brand-new performance standards for the class.

    ...Thanks for watching Honda's Update 2008. We hope you enjoyed learning about the exciting new models that will make 2008 a banner year for performance, versatility, and fun! To receive training credit for this module, simply click "Take Test" in the Honda Online University.