honda SH300: FORK SERVICE: new oil, seals & bitubo spring

replacing the standard honda springs with BITUBO springs and 20W fork oil
valid for sh125, sh150, sh300, and basically any other scooter, just the clip for the top cap maybe different

photo documentation about this pretty easy work
u dont even have to remove plastics from the scooter (beside the mudguard)


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regarding amount of oil = function of the so called "air spring" see oehlins manual for explanations:
https://bit.ly/2CFAInW

Air spring:
A change in oil level will effect the damping forces, not in the early stage of fork
travel but a great deal in the later stage.

When the oil level is raised
The air-spring in the later half of travel is strong, and thus the front fork hard.

When the oil level is lowered
The air-spring in the later half of travel is soft, and thus the front fork soft.

Oil level adjustment As the air trapped between the oil and the top nut acts as an air-spring, a change in oil level will effect the damping forces. Not in the early stage of fork travel, but a great deal in the later stage. A general description of how the oil level/airspring effects the damping forces are shown in Fig.4. The air-spring gives the Öhlins USD fork a progressive spring rate, preventing it from bottoming out hard.

#honda #fork #service

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original bitubo instructions: https://bit.ly/2Z0sbTS

OPERATIONS TO CARRY OUT ON BOTH FORK LEGS:
1. Remove the top cap: unscrew, or push the closing cap inside to release the seeger slot and then remove the
seeger.
2. Extract eventually spacer, then the spring, and turn the leg for empty the oil. Compress and extend the fork leg a
few times to expel any oil left.
3. Pour the special cleaner and repeat emptying (flushing).
4. After letting the fork leg drain for a few minutes, compress it to the end of its run and pour oil BITUBO SAE 20 up to
100 mm from the top; check the level carefully because it is vital for the fork graduality.
5. Compress and extend the leg a few times and leave the fork leg totally extended for a few minutes to get rid of any
air pockets.
6. Check the oil level again and top up as required to the level shown.
7. Insert the spring into the fork leg. If the spring is of the gradual type, position it with its turns close together facing
upwards.
8. Insert the spring spacers: the original ones or (if present) the ones supplied with the Bitubo Spring Kit.
9. Close the leg screw the top cap, or push the cap inside the leg to apply the new Seeger
10. We recommend you do not put pressure onto forks fitted with an air intake valve (if exist).
11. Fit the fork legs into the fork plates and tighten the plate screws (check the tightening torque on the service manual
for the Scooter)
12. Refit the mudguard, wheel and brake calipers following scrupulously the procedure described in the service manual
for the motorcycle.
13. Refit the underbody and all the accessories and complete the operation.