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Buell Forum » 1125R Superbike Board » Archives 001 » Archive through January 07, 2010 » Possible to disable vacuum assist of clutch? « Previous Next »

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Thefleshrocket
Posted on Saturday, December 26, 2009 - 11:28 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

One thing that I am not completely happy with is the fact that the 1125R's clutch engages with the lever almost all of the way out. I've owned other bikes with hydraulic clutches (a Suzuki SV1000S and a Yamaha Vmax) and both of their clutches engaged about midway through the travel, like most cable-clutch bikes are adjusted to do.

I've done some reading on the 1125R's clutch. It's described as a vacuum-assisted clutch that provides slipper-like action. In other words, when the throttles are closed or slightly open and there is significant engine vacuum, the clutch engages farther out in the travel and more gently. When starting from a dead stop, not a lot of throttle is needed so the throttles are mostly closed resulting in a lot of vacuum and causing the clutch to engage gently and far out in the lever travel.

So, presumably, if the vacuum assist could be disabled, the 1125R's clutch would engage like a regular bike's hydraulic clutch, and that's what I want. I don't care about the slipper action--I am masterful with rev-matched downshifts and have never felt the need for a slipper clutch, either on the street or the track.

So, is it possible to disable the vacuum assist on the 1125R's clutch?
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S1125r
Posted on Saturday, December 26, 2009 - 11:38 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Or you could just adjust the clutch lever so that it completely engages the clutch by time it's within a couple of centimeters of the grip and get rid of all the extra play AND still get the vacuum assist.
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Jdugger
Posted on Saturday, December 26, 2009 - 11:48 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I personally don't believe the vacuum assist and where the clutch disengages have anything to do with each other.
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Xtreme6669
Posted on Sunday, December 27, 2009 - 12:55 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

S1125r, you can not adjust it in that far with the stock set up.... If your rolling a 1125r as your screen name would suggest you should know that.... I bitched a lot about how far out the clutch engagement was on this bike when I first got it but now that I'm used to it I don't even notice it any more. But when I take a ride on the old DRZ400 supermoto it makes me remember what a clutch should be like!
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Xnoahx
Posted on Sunday, December 27, 2009 - 01:12 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Just introduce some air into the system, the lever will go a little further down. Boom! Five bucks!
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S1125r
Posted on Sunday, December 27, 2009 - 01:38 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I really should have completed the thought and added Jdugger's info. On my 1125r, the clutch engages at the same point regardless whether the engine is running.

I bitched a lot about the stock clutch set up also, and tried a few things to remedy it, but finally ended up replacing the levers with some spiffy Pazzo's. Yeah, they are expensive for a bit of bling, but I like the shorties and they are more comfortable for me on top of allowing me to more freely adjust travel.
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Jdugger
Posted on Sunday, December 27, 2009 - 08:02 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Have you ever looked at a Magura hydraulic clutch master cylinder? They use mineral oil, and are fully adjustable. Might be the ticket for you.

When you buy, have a loose grip on your fold, and a hand covering your backside.

Adjustable levers only allow one to adjust the point where engagement happens, as you have found.

A Magura clutch MC would allow you to adjust where the lever is in relation to the bar, as well as the leverage/range of the friction zone. Instead of the action being in a relatively narrow range, you could set your bike up to have a huge, wide friction zone.

... and now Brembo offers a similar system. I have the RCS19 brake master cylinder, and I have to say it's the bomb for track riding. Wicked progressive feel without the mush in the stock unit. The adjustable leverage is killer -- really lets you decide how you want the brake to feedback. I suspect the clutch is pretty nice, too.

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Xtreme6669
Posted on Sunday, December 27, 2009 - 12:15 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Me wants!
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Xl1200r
Posted on Sunday, December 27, 2009 - 01:33 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Flesh - I think you're oversimplifying the system and how engine vacuum works. To get a lot of engine vacuum, you need closed or near closed throttle with an engine that's at speed and revving down. At idle, it's not producing nearly as much vacuum as the engine is not revving down any.

And as others have said, the point where the clutch engages and the vacuum assist don't appear to have much to do with anything. I, too, wasn't happy with the clutch, but have gotten more than used to it at this point, and switching between 4 different bikes doesn't cause much issue.
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Thefleshrocket
Posted on Sunday, December 27, 2009 - 10:02 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

XL1200R, there is a lot of engine vacuum whether the bike is at idle with the throttles closed or whether it's at 10,000rpm with the throttles closed (as in a non-rev-matched downshift where the slipper-action of the clutch gets called into play).

I am sure that I can get used to the 1125R's clutch, but I feel like that's a cop-out for getting it to work "properly".
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Thefleshrocket
Posted on Sunday, December 27, 2009 - 10:04 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Jdugger, that master cylinder or the levers are some pretty trick items, but are a no-go for financial reasons. There's no way I can justify spending several hundred bucks for a master cylinder (and probably more than that) when all I want to do is disable the existing vacuum assist. Even aftermarket levers are too rich for my budget.
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Milleniumx1
Posted on Sunday, December 27, 2009 - 11:27 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I love the clutch on my '09R ... Both where it engages, and how it engages. Since I'm new to serious sportbikes, I'll even admit to the slipper saving me a time or two on downshifts. After years of H-D bikes, I took to this clutch action and feel instantly. I know 'feel' is subjective though ...

Mike
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Justa4banger
Posted on Monday, December 28, 2009 - 07:42 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

First off we need to know how the vacuum assist and clutch work in harmony... then you will know whether or not its worth going through the hassle of disabling the vacuum assist.

Personally i think your wasting your time... I say pony up the cash for some levers if it bothers you that much.. the way i figure it, with the money you saved on the bike with the recent discounts, you should have no issue spending some of that "saved" money on levers..
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Jdugger
Posted on Monday, December 28, 2009 - 07:45 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

My guess is the only thing disabling the vacuum assist will do is make the lever action increasingly firm.

Imagine just putting in stiffer clutch springs.

Even with the levers, you are just exchanging trade-offs. Longer throw vs. firmness of action.

No free lunch.
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Kirb
Posted on Monday, December 28, 2009 - 09:03 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I haven't been able to ride my CR more than 50 miles before the snow started, but the problems that a buddy's ducati monster has with it's lousy slave design and lever travel makes this issue sound minor.

I wouldn't see how the stock setup would vary the engagement point, but maybe messes with the 'feel' of the engagement point.

I would think that more adjustable levers would be the easy route.
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Xl1200r
Posted on Monday, December 28, 2009 - 10:04 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Flesh - 'a lot' is relative. If you put a vacuum gauge on an engine and rev it up then close the throttle, the vacuum will start out high and hold stable until it gets close to idle speed where it will decrease by a good amount.

I have no idea how much is needed for for the slipper-action to work, but I would assume it will be far less noticeable, if at all, at idle speeds.
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Buell2001b
Posted on Thursday, December 31, 2009 - 03:10 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

maybe there is somehting wrong with your piston clutch. I have no issues with it. it never seemed out of the ordinary nor it feels any different then the cable cluch on my xb9r and to be honest the 1125r is so much smoother then my xb9r!!
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Kevin_stevens
Posted on Thursday, December 31, 2009 - 08:06 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Geez. Just change the levers or grind down the engagement pad on the stock one. It doesn't have anything to do with the vacuum assist, Buell just didn't put the adjustment range in the normal place.

KeS
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Brumbear
Posted on Thursday, December 31, 2009 - 08:20 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

NO now HTFU and ride....
or wait till the snow melts anyway
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Xtreme6669
Posted on Friday, January 01, 2010 - 12:52 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I know STFU but what is HTFU?
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Froggy
Posted on Friday, January 01, 2010 - 01:10 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

It is a meme that was started on here by Danger_Dave

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Captain_america
Posted on Tuesday, January 05, 2010 - 07:15 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

!!!!!!!!CHOPPER REID IS THE BEST!!!!!!!!
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