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Which Ducati clutch radial master cylinders are an easy swap for the original on an 02 ST4S.
The original is not adjustable.

I replaced the plates and installed an Oberon slave last season but can’t get quite enough release when the bikes hot.
Neutrals hard to find and there’s an unpleasant clunk into first gear.
Its been bled thoroughly many times including the tipping over to the right to release master cylinder air but no improvement.I don't think its air in the system.
Plates are adjusted to spec and lithiumed and generally work well.

I rode it this way all last season hoping some plate wear would help and its almost good enough...but not quite.
Town runs were never its favourite way to play when hot and with this clutch its even less pleasant.

I’ve seen a couple of posts recommending using the 999 or the 749 clutch master as a solution.
Can anyone confirm they are an easy fit and also add if there are other ducati clutch master cylinders that would work.

Thanks.
 

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Which Ducati clutch radial master cylinders are an easy swap for the original on an 02 ST4S.
The original is not adjustable.

I replaced the plates and installed an Oberon slave last season but can’t get quite enough release when the bikes hot.
Neutrals hard to find and there’s an unpleasant clunk into first gear.
Its been bled thoroughly many times including the tipping over to the right to release master cylinder air but no improvement.I don't think its air in the system.
Plates are adjusted to spec and lithiumed and generally work well.

I rode it this way all last season hoping some plate wear would help and its almost good enough...but not quite.
Town runs were never its favourite way to play when hot and with this clutch its even less pleasant.

I’ve seen a couple of posts recommending using the 999 or the 749 clutch master as a solution.
Can anyone confirm they are an easy fit and also add if there are other ducati clutch master cylinders that would work.

Thanks.
I don't think a Radial master is going to cure your clutch problems, but I have however replaced my brake master cylinder with a Super Bike unit.

Think it through, clutch plates wear and so do baskets, so disengagement is an issue if their is a problem. Hydraulics either work or they don't! Radial stuff does look cool though!

Craig
 

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When the lever is released, a compensation port must be exposed to allow more fluid to enter. However, the port just needs to be barely exposed. If the piston withdraws more than necessary, you may not be able to push enough fluid. That can be a lever adjuster that does not move enough or it can be that the pushrod is screwed too far into the pivot bushing. The pushrod is the little rod that goes from the lever into the piston end. In some cases, the pushrod may be too short to get maximum range without covering the compensation port, like in the event of a slave variance. The only way to see if you have maximum range is to keep extending the pushrod until it will no longer bring more fluid in when bleeding. If the rod is not long enough, you can make a longer one in a variety of ways, For one, you can go to the hardware store and get a bolt of the same thread and trim the head off and taper the end similarly to the original but longer. The taper is not particularly sensitive to precision so lack of a lathe means a file or other means cam be used.

If the pushrod is difficult to loosen or remove, possible due to a locking agent, you can put the pushrod in a vice and unscrew the lever.
 

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Which Ducati clutch radial master cylinders are an easy swap for the original on an 02 ST4S.
The original is not adjustable.

I replaced the plates and installed an Oberon slave last season but can’t get quite enough release when the bikes hot.
Neutrals hard to find and there’s an unpleasant clunk into first gear.
Its been bled thoroughly many times including the tipping over to the right to release master cylinder air but no improvement.I don't think its air in the system.
Plates are adjusted to spec and lithiumed and generally work well.

I rode it this way all last season hoping some plate wear would help and its almost good enough...but not quite.
Town runs were never its favourite way to play when hot and with this clutch its even less pleasant.

I’ve seen a couple of posts recommending using the 999 or the 749 clutch master as a solution.
Can anyone confirm they are an easy fit and also add if there are other ducati clutch master cylinders that would work.

Thanks.
I would suggest replacing the original slave, to see a difference, after market ones don't throw as far.

Craig
 
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Sounds like you've verified your stack height is 38 +/- 5 mm? Depending on the bore size of the slave you're using, it may work better if you set the stack height on the low side by swapping a few steels with thinner ones...

None of the hydraulic master cylinders are adjustable. Later bikes come with an adjustable lever, but you can get a set of adjustable levers for the style master that is on the bike currently. Hit up eBay and grab a set of Chinese knock-offs for 20 - 30 bucks to test your theory of not enough pull / release. Just an observation though... I have adjustable levers on my bike with OEM masters. I do not need them adjusted out all the way to get enough clutch pull with the OEM slave (see story below). I think I did when I had the aftermarket slave. I also don't remember how the non adjustable levers that came on the bike compare position-wise to the adjustables.

My personal experience with aftermarket slaves is lukewarm. I had an Evlouzione slave until pretty recently. Lever pull was easier and generally things were fine. Slave started to leak a bit after many years of use and Evoluzione is long gone for rebuild kits. I am sure I could source o rings for it, but bought a new take off OEM slave instead at my favorite vendor (eBay). I have to tell you, the harder lever pull is negligible and the extra clutch release made shifting and finding neutral easy and smooth again. Most of the aftermarket slaves have a larger diameter bore, essentially gearing-down the system. Easier to pull the lever, but the pressure plate moves less. As I am sure you know, there are many threads discussing problems here. They are nice, in that they are generally rebuildable and add a bit of bling, but the OEM item works best IMHO. Also, the bikes with radial masters you are talking about use the same OEM slaves your bike did. I don't know that is will make much difference unless the master's bore size is different compared to the big pivot Brembo on your bike now. You'd need a clutch line too. Banjo bolt is mounted on the bottom with a radial master.
 

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Discussion Starter #7
Thanks for the thoughts guys.I didn't know the later models adjustability was just in the levers.
Not much point in going radial then.

I'll play with extending the existing push rod a little.Should be easy to do initially with small spacers to watch what happens before blocking the little hole that feeds fluid back into the cylinder.


I replaced the OEM slave because it was leaking so its not an option to refit and compare.
I'd run the original setup with 2 clutch springs removed for years but had put them back as the plates neared their end and began to slip.I thought 45000 miles on the original plates was good value for a bike ridden hard and often 2 up with luggage.

The Oberon slave gives a similar feel to having 2 springs out of the clutch plate but with the noted release probs.Had I known that then I would probably have just bought an OEM replacement slave.

Shazaams posts/charts in the hall of wisdom have been helpful and do point out that what has happened to me has happened to others re aftermarket slaves.http://www.ducati.ms/forums/80-hall-wisdom/29044-clutch-master-cylinder-adjustment.html

Will post back when I've fiddled with the master pushrod.
 
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