Walkers World - Changing your hydraulic clutch oil

Author: Words & photos by Geoff Walker

More and more bikes are coming from the factory with a hydraulic clutch fitted as standard. One of the benefits of the hydraulic clutch is the fact that the oil in the unit keeps a constant perfect pressure in the system.

And this means there's no adjustment required during riding, whether you're at the track running motos or you're out on the trails riding with your buddies for hours on end. 

With a cable operated clutch you have some maintenance to do but with cable oiling and pivot cleaning and greasing you can keep an excellent feeling clutch. The hydraulic clutch systems offer a great feeling pretty much all the time but they also require some maintenance to keep things working as they should. Oil can only take so much abuse and with the system being subjected to extreme temperatures the oil will go off, giving you a pretty crappy feeling unit.

That's the bad news! The good news is by following just a few easy steps you can keep your hydro clutch working like a dream.

Clutch touch!

Cables are good but hydraulics are better - dbr's chief hose handler shows you the golden touch with your clutch

As with all maintenance, make sure the areas your gonna work on are clean and go through this simple tool check.

- Good quality hydraulic clutch oil

- Phillips screwdriver

- 8mm ring spanner

- Approx 50mm of carb overflow pipe and a decent sized syringe (heat one end of the rubber pipe and push it onto the end of the syringe, making sure there is a good n' tight fit)

Before you start make sure the master cylinder is sparkly clean

Loosen and carefully remove the top from the clutch master cylinder, making sure no crud gets in the mix. At this point check the colour of the oil - if it's clean and clear then pop the top back into place and chill out. But if the oil is a nasty grey colour it's time to refresh the system.

	To keep things simple, the lever and master cylinder are at the top of the system and the slave cylinder is at the other end of the hydraulic line. The slave cylinder operates a piston system and, when the lever is pulled in, the pressure created pushes the piston in the slave cylinder out onto an actuating control rod which controls the pressure release of the clutch plates. Simple as that...
	The main part of this simple job is undertaken at the slave cylinder. You must fill your syringe with the hydraulic clutch oil, making sure there are no air bubbles present in the puppy.
	With the syringe filled with oil the next step is to get the ring spanner onto the bleed nipple on the top of the slave cylinder.
	Next step is to get the syringe connected onto the bleed nipple. You must pressurise the syringe a little as you pop it onto the nipple as this will take any excess air from the rubber connecting pipe - this means you're not pushing air up through the system.
	With a little pressure on the connected syringe simply undo the bleed nipple a fraction and pressurise the system. Push the fluid through, after this re-tighten the nipple. Make sure you wrap some cloth or paper roll around the master cylinder or you're in for makin' a mess when the old oil is pushed through the system and starts to overflow.
	When the oil is lookin' twinkly and, quite frankly, shhparkly, pump the lever to make sure there's a good feeling. If the clutch action feels a little bit dodge just pump the lever a few times, then hold it in and quickly crack the bleed nipple loose for a fraction of a second then nip it tight again. This action will allow the small air bubble which sometimes floats around just inside the slave cylinder to escape as oil squirts out, giving you the perfect feeling and operating hydraulic clutch.
	Check the level is around two thirds full in the master cylinder then pop the top on, nip it up, clean any excess oil from the affected areas and go holeshot...