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I've been hearing that replacing this with a 28mm would reduce lever effort. After picking up bike and promptly getting stuck in traffic I really appreciated this modification. :)
 

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Sorry if this is a dumb question, but why would the cluch slave cylinder size have anything to do with how easy it is to find neutral? Isn't the clutch either engaged or it isn't? I would think finding or not finding nuetral would have more to do with the clutch plates and cogs?
 

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The Engineer (Tell your mom hey)
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Sorry if this is a dumb question, but why would the cluch slave cylinder size have anything to do with how easy it is to find neutral? Isn't the clutch either engaged or it isn't? I would think finding or not finding nuetral would have more to do with the clutch plates and cogs?
it doesn't .. but it makes your hand less tired from holding the clutch for so long while looking for neutral!!! :)
 

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Evidentially I didn't do enough research on this subject. replaced mine with aDucati Performance and it was 30mm. I feel no difference. I should have gone with 28mm.
Ken
 

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Sorry if this is a dumb question, but why would the cluch slave cylinder size have anything to do with how easy it is to find neutral? Isn't the clutch either engaged or it isn't? I would think finding or not finding nuetral would have more to do with the clutch plates and cogs?
You have to understand what happens when you pull the clutch lever.

Lever effort: Your master cylinder has a piston that pushes a fixed amount of fluid, if you increase the diameter of the slave cylinder piston, you have increased the surface area that the hydraulic pressure pushes against (you have lowered the pounds per square inch rating) That is what causes the reduced lever effort.

"Finding Neutral": Remember that the master cylinder piston pushes a fixed amount of fluid. If you increase the diameter of the slave cylinder piston, the larger diameter piston will not be able to travel as far as smaller diameter stock piston. Since the stroke or travel length of the slave cylinder is reduced, the pressure plate does not release as far as it did before, if the clutch does not completely disengage, it can be harder to hit neutral.
 

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You have to understand what happens when you pull the clutch lever.

Lever effort: Your master cylinder has a piston that pushes a fixed amount of fluid, if you increase the diameter of the slave cylinder piston, you have increased the surface area that the hydraulic pressure pushes against (you have lowered the pounds per square inch rating) That is what causes the reduced lever effort.

"Finding Neutral": Remember that the master cylinder piston pushes a fixed amount of fluid. If you increase the diameter of the slave cylinder piston, the larger diameter piston will not be able to travel as far as smaller diameter stock piston. Since the stroke or travel length of the slave cylinder is reduced, the pressure plate does not release as far as it did before, if the clutch does not completely disengage, it can be harder to hit neutral.
ok, that makes sense. So it would follow that with a larger slave, I should have the clutch lever adjusted as far out from the bar, so when I engage it, I can get as much travel in the lever, and consequently the piston in the master cylinder. Right?
 

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Lever effort: Your master cylinder has a piston that pushes a fixed amount of fluid, if you increase the diameter of the slave cylinder piston, you have increased the surface area that the hydraulic pressure pushes against (you have lowered the pounds per square inch rating) That is what causes the reduced lever effort.
I am probably missing something here but if going from a 30mm to a 28mm cylinder you are reducing the diameter anot not increasing, so how does it make it easier based on above? Is the stock cylinder 30mm?

Thanks,
Ken
 

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I'm confused, too. What are the trade-offs between the 28, 29, and 30mm slave?

After being caught in not one, but two, hour long traffic jams, this is going to be one of my first mods. The clutch felt great until I spend an hour feathering it through stop and go traffic.
 

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The Engineer (Tell your mom hey)
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a larger clutch slave diameter should decrease the relative effort required to use it and also decrease the amount of travel the clutch will have for a given travel length of the master lever. This said you have a lot of play in the lever and master cylinder. So the travel distance for the slave cylinder (in releasing the clutch pressure) shouldn't really be an issue. If you want and easier clutch,, try the the 30mm first.
 

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The Engineer (Tell your mom hey)
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25mm I believe.
this chart was originally posted by Shazaam in another thread

 

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Sorry if this is a dumb question, but why would the cluch slave cylinder size have anything to do with how easy it is to find neutral? Isn't the clutch either engaged or it isn't? I would think finding or not finding nuetral would have more to do with the clutch plates and cogs?
In theory, you're completely correct. It would be purely mental.

But, in practice, it can make a difference because the engagement/disengagement point will differ between slave cylinders, relative to a given amount of lever pull. This is exacerbated of course, if you use 2 or 3 finger lever pulls where you're routinely not all the way to the bar with your clutch lever.

Simply: in practice, a given slave cylinder may cause more complete disengagement relative to lever pull and thereby make finding neutral easier.
 

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Not sure how to interpret the chart. So with a StreetfighterS, is the Yoyodine a problem (although I thought it was 27.5%)?
 
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