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- From 2005 year model, replacing with RM250 with 2-stroke engine, RM-Z450 with 4-stroke engine was introduced in the market. - From 2008 year model, fuel injection system was introduced instead of carburetor system - From 2013 year model, separate function front fork (SFF) was introduced instead of conventional front fork. - From 2015 year model, the front fork is updated as SFF-Air. 2
RM-Z450 got 1 world title, 6 AMA titles and 10 national titles from 2005 to 2013 year. 3
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Mode-A assists hole shot with smoother engine response. It is suitable to novice riders and riders who is not good at start at race. In respect of the ground condition, it is effective to slippery ground condition. Mode-B assists hole shot with aggressive engine response. It is suitable to expert riders having good skill at start. In respect of the ground condition, it is effective to good-grip ground condition. 7
Champion riders involved in development of S-HAC. 8
When you use holeshot assist control, you need to press the switch to select either A or B-mode after engine start. To select A-mode, hold pressing the switch for one second. To select B-mode, hold pressing the switch for two seconds. After the mode selection, S-HAC mode is canceled if you press the switch again. The switch button lights on or flashing, and it indicates the selected mode condition. 9
Ignition timing is retarded in A-mode to stabilize the machine at the moment of start by increasing tire thrust force to the ground while reducing chance of the wheel spinning. The ignition map returns to the normal map when shifting up to 3rd gear position or 1.2 seconds after the start whichever comes first. 10
Ignition timing is advanced in B-mode producing strong power and response. The ignition map returns to the normal map when shifting up to 4th gear position, 4.5 seconds after the start or closing throttle, whichever comes first. 11
Tire traction force at start varies by throttle position and gear position. Therefore, ECM monitors throttle position and gear position to optimize the ignition timing at the short moment of start. Program of the ignition timing adjustment is different in the modes A and B. 12
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Due to the new system of S-HAC, multi-function indicator light is newly installed on 2015 year model. The indicator light functions not only for S-HAC but also for engine run time check and MX-tuner answer back. Up to 2014 year model, you need to have the option light device for engine run time check and MX-tuner answer back Now the option light device is no more necessary. 15
Name of terminal No. 4 was changed from FI indicator to Indicator output. FI indicator means output to the option light device (FI indicator light), and Indicator output means output to multi-function indicator light. Terminal No. 29 was added for S-HAC switch. Other terminals are same as 2014 year model. 16
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Up to 2014 year model, at the kick start operation, kick rotation force applied to the kick drive gear by kick lever is transferred to kick idle gear having breather function. 25
On 2015 year model, a new gear was newly located as a kick idle gear. The kick idle gear having breather function on 2014 year model remains located in the same location. However the gear has only the breather function and no more function of kick idle gear. 26
Decompression device design was totally changed. Operation angle of decompression lever was decreased and the decompression arm shape was changed to optimize the tappet-lift timing and amount. 27
New decompression device improved in secure operation to the exhaust tappet, resulting in ease engine start. 28
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Straight water passage increased water flow by 16%. 30
Connection pipe shape was changed from T-shape to Y-shape to improve water flow from left radiator. 31
Precision of gear matching with the counter shaft and drive shaft was increased. 32
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Torque at low range and rev-up character were improved. 34
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Spring fork unit at right side was changed to air spring unit. Eliminating the coil spring reduced the weight. 39
Same as 2014 year model, each right and left fork has separate function. Right fork is air spring unit and left fork is hydraulic damper unit. 40
Development of the air front fork was done with factory machines in the race activity. 41
While coil spring needs to be replaced to change spring rate on conventional fork, air fork only needs to adjust air pressure.. During race, time to change spring rate is much shortened, and customer does not need to purchase fork spring with different rate. Eliminating coil spring as the heaviest part of front fork achieved 1,100 g weight reduction. Air spring fork is free from heat of the separated hydraulic damper fork. This benefit is the same as the previous SFF. 42
Piston diameter increased by 1 mm improved to gain stabilized damping performance. Inner rod increased by 2.5 mm optimized the stiffness. 43
Under free condition of the air fork, increase of air volume in the inner air chamber acts to stretche the fork. This condition is the same in outer air chamber. However, that is opposite in balance air chamber. Increase of air volume in the balance air chamber acts to retract the fork. 44
Left picture shows SFF on 2014 year model, and right picture shows SFF-Air on 2015 year model. Coil spring (red part) is replaced with inner air chamber of air fork. Yellow space on both coil spring fork and air spring fork has the same function. According to inner tube retracted, air space of yellow part is compressed and it reacts as air spring. This means that the coil spring fork also has a sub air-spring function producing tension force together with the coil spring. As to balance air chamber (blue part), there is not the same spring function on the coil spring fork. 45
This is a simple drawing showing construction of the 3 chambers. When the fork is retracted, red and yellow air volumes decrease (pressure increase) while air volume of blue part increases (pressure decrease). 46
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Two air valves for inner air chamber and outer air chamber are located on the top of fork body. Outer circle mark indicates the outer air chamber and inner dot mark indicates the inner air chamber. 49
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(1) Inner air chamber This chamber is pressurized to 1200 kpa (standard setting) and the air pressure acts to stretch the front fork, and it mainly determines the suspension force throughout the fork stroke. (2) Balance air chamber This chamber is also pressurized to 1200 kpa (standard setting) and the air pressure acts to shorten the front fork. (Opposed force against the air pressure of inner air chamber) According to increase of the fork stroke, the inner air pressure increases and the balance air pressure decreases. The balance air pressure is highest in the fork fully-stretched condition, and it determines the suspension force in the initial stroke range in combination with the inner air pressure. The total suspension force character throughout the fork stroke is determined by the combination force of produced by the inner air chamber and the balance air chamber. (3) Outer air chamber Outer air chamber is the internal space of fork outer tube surrounding the inner air chamber. This chamber is not pressurized (0 kpa) in the standard setting unlike the inner air chamber and the balance air chamber. Suspension setting can be changed 51
harder by the pressure adjustment of inner air chamber and balance air chamber within the specified range in the owner s service manual. However, after the setting adjustment to harder, if a customer needs further hard setting, outer air pressure can be increased to obtain further hard setting. 51
Piston diameter increased by 1 mm improved to gain stabilized damping performance. Inner rod increased by 2.5 mm optimized the stiffness balance of right and left forks. Inner tube diameter increased by 1 mm optimized the fork stiffness. 52
Air spring has a progressive character. 53
In the case of changing air pressure of both inner air chamber and outer air chamber, spring force change in the initial stroke is minimal and large in the end stroke by keeping the progressive character. 54
In the case of changing the inner air only, the spring force changes in overall stroke range. 55
In the case of increasing the balance air only, the spring force at the initial stroke becomes soft. In the case of decreasing the balance air only, the spring force at the initial stroke becomes hard. The point is that the balance air affects the setting in the initial stroke. 56
Imagine an injector. 57
Plug at the both ends for airtightness. 58
Now A and B are in atmospheric pressure condition. And then pressurize both up to 1200 kpa. This is the same as the standard pressure of inner air and balance air of SFF-Air fork. In this condition, the piston seems to be floating between A and B. 59
When the piston goes up, A volume decreases and pressure increases and B volume increases and pressure decreases. By the piston movement amount, A pressure increases accordingly and it produces a pushing force against the piston like a coil spring. 60
When the piston goes down, A volume increases and pressure decreases and B volume decreases and the pressure increases. 61
A is equivalent to the inner air chamber of the air fork. B is equivalent to the balance air chamber inner of the air fork. 62
The piston receives the both force from A and B. Inner air creates a force to push down the piston, and balance air creates a force to push up the piston. 63
Left drawing shows a injector with B air chamber. Right drawing shows a injector without B. Under free load condition to the piston, the piston is in a position that A and B pressures are in balance, and a minimal external force can start pushing up the piston. The relationship between the piston stroke and the reaction force (air spring force) is shown in the graphic drawings. If B does not exists, a certain force is required to start pushing up the piston. This condition on a front fork means an excessive hard setting of spring pre-load. 64
In this drawing, the injector is covered by a cylinder-shaped case producing another air chamber kept airtight.. This cylinder-shaped case is equivalent to the outer tube of front fork, and the yellow air chamber is equivalent to outer air chamber of SFF-Air fork. 65
1. Air pressure of air chambers of air fork must be checked before riding as well as tire. 2. Use a hand-operation pump to charge air. Never use a compressor because instant charge of high pressure may damage the inner parts of air fork. 3. Order of charging air to the 3 air chambers are specified. Air charge in different order will result in abnormal setting against the desired setting by SMC. 4. Each of 3 air chambers requires the specified amount of fork oil. Unlike a conventional front fork, you need to pour fork oil into three air chambers one by one. Oil in each chamber slightly leaks down to balance air chamber gradually by repeated fork stroke during race over time, and neglecting the fork oil replacement may cause oil level change in the air chambers. And the oil level change affects the air volume of the 3 air chambers. And the remarkable air volume change will result in the setting. Air spring character changes by air volume if adjusted the same pressure.. On a conventional front fork, addition of fork oil amount over the specified amount makes fork setting hard. This means that air pressure becomes high shortly according to the fork stroke due to the reduced inner air volume of front fork. Therefore, make sure to replace the front fork oil following the specified schedule 5. Oil may jet out from the valve when releasing air pressure. If the fork is lying on a desk, it allows the oil to move around the valve and enables oil jetting out when releasing air. To avoid the risk, place a rag around the valve when releasing air. 66
Air pressure of air chambers of air fork must be checked before riding as well as tire. 67
Use a hand-operation pump to charge air. Never use a compressor because instant charge of high pressure may damage the inner parts of air fork. 68
Air pump should be able to charge air up to 1500 kpa. Desirable pressure gauge scale is 1000 1500 kpa. And 50 kpa scale step is desirable for precise setting adjustment. 69
Adjustable range of outer air chamber is 0 130 kpa, and it is much lower than inner air chamber and balance air chamber. Desirable pressure gauge scale is 0 350 kpa for outer air chamber. And 10 kpa scale step is desirable for precise setting adjustment. 70
Because adjustable pressure range of outer air chamber is much lower than the other air chambers, 2 air gauges with different scale should be prepared. Air gauge is attached to this sample of air pump and the air gauge is detachable. Two different scale gauges can be attach to the pump body. This can allow air charging and adjusting the air pressure with one air pump for all 3 air chambers in short time. 71
Valve attachment of this air pump sample is screw down type. This type is recommended for the air pump or air gauge using for the air fork. When charging or adjusting air pressure of tire, air pressure of tire is momently released from the tire valve at the moment that the air gauge attachment is removed from the tire valve after the tire air adjustment operation. This type of valve attachment prevents momentary air release such as above. Different from tire air adjustment, air pressure of air fork is much higher. Therefore, for precise setting adjustment to certain pressure value, air release at the end of pressure check job with an air gauge should be minimized. 72
This air pump sample has quick air release device. Pressing the button to release the air. It is convenient to adjust air pressure to the desired value shortly. It is recommended to use an air gauge having such device. 73
Air pressure check and adjustment must be done in condition that the front wheel is off from the ground. The specified air pressure value in the owner s service manual is determined in this free condition of the front fork. 74
Air adjustment in this condition cannot provide the correct setting. 75
Even in this condition, the fork inner tube is retracted by the machine own weight. Air adjustment in this condition also cannot provide the correct setting. 76
The front wheel must be lift up with a stand. 77
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This is quick reference video showing the air charge and its order. Click the center of pictures with video icon to start short movies. 79
This slide shows bad example of front fork condition if air pressure is adjusted in the following incorrect order. Incorrect order: 1st balance air (1200 kpa), 2nd Inner air (1200 kpa), 3rd inner air (0 kpa) (Note: Initial condition before air charging is 0 kpa in all 3 chambers.) In this incorrect order, fork inner tube is retracted fully by the first air charging (1200 kpa) to the balance air chamber. Then after that, inner air chamber is pressurized to 1200 kpa and the inner tube is stretched and stopped as shown in the right picture. In this condition, the front fork does not work properly. Contrary to the above, in the correct order, fork inner tube is stretched fully by the first air charging (1200 kpa) to the inner air chamber. Then after that, balance air chamber is pressurized to 1200 kpa and the inner tube is retracted and stopped as shown in the left picture. As you can see, although you take the same pressure adjustment, the fork condition is quite different by the air charging order. 80
This slide explains why the difference of front fork in the previous slide occur. The piston stays in the center of injector with the balanced air pressure of 500 kpa. In this condition, if you charge air to 1000 kpa at the same time, the piston will stay in the same center position. 81
Different from the previous slide, if charging air to 1000 kpa from right side first and then charge air to 1000 kpa from the left, the piston will stop and stay at the left side of the injector body. By the first air charge from the right side, the piston moves to left and the left chamber s pressure increased from the original pressure 500 kpa. Then left chamber pressure can be increased to 1000 kpa by small amount charged from the left side. 82
Imagine the injector drawing as the air front fork. For example of the air pressure adjustment to the standard setting: Firstly air is charged to the inner chamber to 1200 kpa. This makes the piston moving down. (fork inner tube is stretched.) Secondary pressure in the outer air chamber is adjusted to zero. Finally air is charged to the balance air chamber to 1200 kpa. This makes the piston moving up slightly. 83
Each of 3 air chambers requires the specified amount of fork oil. Unlike a conventional front fork, you need to pour fork oil into three air chambers one by one. Oil in each chamber slightly leaks down to balance air chamber gradually by repeated fork stroke during race over time, and neglecting the fork oil replacement may cause oil level change in the air chambers. And the oil level change affects the air volume of the 3 air chambers. And the remarkable air volume change will result in the setting. Air spring character changes by air volume if adjusted the same pressure.. On a conventional front fork, addition of fork oil amount over the specified amount makes fork setting hard. This mechanism is that the fork inner air becomes higher pressure by the fork stroke than the standard amount of fork oil due to the reduced inner air volume of front fork. Therefore, make sure to replace the front fork oil following the specified schedule 84
Oil may jet out from the valve when releasing air pressure. If the fork is lying on a desk, it allows the oil to move around the valve and enables oil jetting out when releasing air. To avoid the risk, place a rag around the valve when releasing air. 85
This is an extra explanation about motorcycle washing. In Suzuki owner s manual, use of high-pressure washer is prohibited because high water pressure may damage certain electric, engine chassis parts. 86
However some customer uses high pressure washer as shown in the picture. 87
As to high pressure washer using to clean a front fork, high pressure water jet may push mad and dust into the dust seal lip. Then the accumulated mad and dust at the dust seal rub the fork inner tube, and the mad and dust may cause damage of inner oil seal resulting in oil leakage. On SFF-Air fork, such seal damage causes air leakage which spoils air spring function. 88