GSXR 1100 Clutch master cylinder help

[DeeMaxBack]

I am currently building a 1990 GSXR 1100 L Streetfighter with an '86 1100 engine, I finally have it starting and running but the current issue is in the lack of driving.

Having built this bike from the ground up with no parts to begin with, I went for what I thought would be good options through the build process. I got a set of Aprilia RSV1000R master cylinders and levers and the brake works fine but it seems that the master cylinder isn't displacing enough fluid to fully engage the clutch when the lever is fully pulled. It's as if the it's just about to start engaging, then the lever hits the bars. It's not a question of whether the system is bled properly, as I'm 99 percent confident the issue is with the master cylinder.

 

My question lies in that firstly, what is the cylinder bore of the original 1100 master cylinder and secondly, does anyone have an idea of any recommendations as to any from another model (with a remote reservoir) that will do the job i'm looking for it to do and as a bonus, if it looks similar/ same as what I already have (in appearance) then even better.

 

Any help much appreciated in advance! Pic attached of my current set-up.

[Upshotknothole]

Are you sure you have the right push rod for the clutch behind the sprocket cover? I can't remember the length off the top of my head for the hydraulics, but if you search on here you'll find it. Does the clutch lever feel like it's engaging at the beginning of the pull or only at the end?

Can't tell if the lever is being held in by the wall in that photo, but that lever looks way too close to the bar.

[TonyGee]

Use a cable clutch. 

[Upshotknothole]

5 minutes ago, TonyGee said:

Use a cable clutch. 

This!

[Gixer1460]

7 hours ago, TonyGee said:

Use a cable clutch. 

Totally unnecessary on an 1100 - keep it for 'baby' 750's. And more feel argument is bollux IMO - hydraulic fluid is non compressible ie. pressure in = pressure out, cables stretch / compress = less accuracy !

10 hours ago, Upshotknothole said:

Are you sure you have the right push rod for the clutch behind the sprocket cover? I can't remember the length off the top of my head for the hydraulics, but if you search on here you'll find it. Does the clutch lever feel like it's engaging at the beginning of the pull or only at the end?

Can't tell if the lever is being held in by the wall in that photo, but that lever looks way too close to the bar.

All reasonable points. And if that lever is static / at rest, then something is deffo incorrect - I would expect to at least stretch my fingers straight to start pulling a correctly functional lever & clutch! I think std bore size is 14mm? but don't quote me on that!

[TonyGee]

1 hour ago, Gixer1460 said:

Totally unnecessary on an 1100 - keep it for 'baby' 750's. And more feel argument is bollux IMO - hydraulic fluid is non compressible ie. pressure in = pressure out, cables stretch / compress = less accuracy !

well IMO their is a difference in feel or i wouldn't prefer them !!!!!  and yeah cables can stretch but how hard is it to turn the adjuster screw at the lever ?  and hydraulic systems can leak from the hose/banjo's/master cylinder seals and the slave cylinder seal !!!!!!!!!!   i'll stick to cable. 

[Dezza]

Cable clutches - fewer parts so more simplicity, lighter, takes less space, cheaper, easier to fix when it fucks up. Maybe this (partially) explains why so many manufacturers have moved back to fitting them as OEM.

[Captain Chaos]

one advantage of hydraulic is that the line can be installed with tight bends while a cable can't.

[Captain Chaos]

and it's self adjusting.

[TonyGee]

1 hour ago, Captain Chaos said:

and it's self adjusting.

your making it sound like its a problem with cables ?  i find that as the engine warms up it effects the free play at the clutch lever so i adjust it as im riding, to me thats part of owning/riding an old bike and part of the character of them, even using a choke lever.  i like the mechanicals of them, a bit like the old brit bikes back when you had to adjust the timing and other stuff.    modern bikes are boring where you just press a button and a fecking computer takes over. 

[Captain Chaos]

1 hour ago, TonyGee said:

your making it sound like its a problem with cables ? 

I'm not making it sound like anything, I'm just mentioning advantages of hydraulic clutch operation because some people feel no love for it.

Personally I also prefer a well maintained and adjusted cable over hydraulic.

[TonyGee]

5 minutes ago, Captain Chaos said:

I'm not making it sound like anything, I'm just mentioning advantages of hydraulic clutch operation because some people feel no love for it.

Personally I also prefer a well maintained and adjusted cable over hydraulic.

[fab]

are you sure that's the correct lever for that master cylinder

it should have twice that much travel at rest.

[Upshotknothole]

16 minutes ago, Captain Chaos said:

I'm not making it sound like anything, I'm just mentioning advantages of hydraulic clutch operation because some people feel no love for it.

Personally I also prefer a well maintained and adjusted cable over hydraulic.

I've had both on 1100s and was actually thinking about switching one of my bikes back to hydraulic, only because we can't lane split where I live now and the clutch gets a little tiresome in stop and go traffic. Otherwise I tend to prefer the feel and look of a cable clutch. I think it all really just boils down to personal preference.

[Gixer1460]

18 hours ago, Captain Chaos said:

and it's self adjusting.

And it doesn't break at the most inconvenient moment! Had two cables break and one almost ready to against hydraulics that once bled were faultless and never touched again - just sayin' like!

[TonyGee]

1 hour ago, Gixer1460 said:

And it doesn't break at the most inconvenient moment! Had two cables break and one almost ready to against hydraulics that once bled were faultless and never touched again - just sayin' like!

i don't think we are gona agree on this !!!! but i can say in well over 40 years ive never had a cable snap on me but i have had to replace worn/fraid ones though. i have been let down on on my 1200 bandit with a seal leak   at the end of the day its all down to maintanance and if both systems are in good fettle then all is well in the world.   we'll put this to bed now 

[Toddy64]

Not sure if this may help, but my 89 1100 K deffo runs a 14mm piston as standard (its cast into the master cylinder) my push rod measures 101.5mm last time i checked.

Had similar issues to yourself trying to tidy up the Renthal bars with a modern looking unit, Cheap Chinese Brembo copy a non starter, got close with a 14mm VTR1000 unit, even tried 100mm and 104mm rods to no avail. 

So ended going back to standard MC and typically its working fine (other than clutch slip) but that's another story

Hope this helps

Edited November 2, 2021 by Toddy64
spelling

[DeeMaxBack]

23 hours ago, Toddy64 said:

Not sure if this may help, but my 89 1100 K deffo runs a 14mm piston as standard (its cast into the master cylinder) my push rod measures 101.5mm last time i checked.

Had similar issues to yourself trying to tidy up the Renthal bars with a modern looking unit, Cheap Chinese Brembo copy a non starter, got close with a 14mm VTR1000 unit, even tried 100mm and 104mm rods to no avail. 

So ended going back to standard MC and typically its working fine (other than clutch slip) but that's another story

Hope this helps

Thank you very much dude this is exactly what I needed to know! 

I also should add that the picture is slightly deceiving, it is lying up against the shed wall in this photo. The lever usually sits out its normal resting position with a good handful of grab available until it hits the bars.

And to address the other replies above, thank you everyone for your input! My personal preference lies with the hydraulic clutch for the smoother feel. I have cable on my 750L and although it's great, I much prefer my 1100M hydraulic clutch so I'd like to stick with the setup that's on it currently as there has already been a few hard earned pennies spent on the clutch system so far!

The clutch push rod was fabricated to fit as the engine is running an offset front sprocket which prevents the sprocket cover and slave cylinder from sitting flush with the engine. So aluminium spacers were machined exactly 10mm in length to space out the cover, which we then compensated for the push rod by machining it 10mm longer than the standard length. So all is good down that end and as far as I remember, I had an OE master connected while the engine was being built and the clutch operated as it should internally (visually). It's only since I changed set up to the Aprilia master, does it not engage properly. You get around 30mm of free travel on the lever until you just about feel it starting to engage.

I'm nearly sure as I said, that the master cylinder piston size is too small, so ill try see if I can pick up a VTR unit as Toddy recommended and see how it fairs out!

 

Thanks again for all the replies and just to stir the pot on the cable-hydraulic argument, cable clutches are for women.....end of

[TonyGee]

1 hour ago, DeeMaxBack said:

just to stir the pot on the cable-hydraulic argument, cable clutches are for women.....end of

lol   is the because womens hands are stronger than men's ?    

[DeeMaxBack]

30 minutes ago, TonyGee said:

lol   is the because womens hands are stronger than men's ?    

No because the women love pulling cables, need regular oiling and they can be tight as f*%k... instead of being a mans clutch with a piston and a load of built-up fluid that never gets to go anywhere 

[markfoggy]

There is something going on with the cylinder sizes of these that is a little strange. Even Bimota sleeved down the slave cylinder to get it to work with a Brembo.

I can only guess that the lever point on the original is set for really long travel. Modern Radial master cylinders just don't seem to move enough fluid.

@370 Steve has fixed his with a different Slave and Master combo, but not proven yet.

I'm keen to find an answer to this....

Help. 

[DeeMaxBack]

5 minutes ago, markfoggy said:

There is something going on with the cylinder sizes of these that is a little strange. Even Bimota sleeved down the slave cylinder to get it to work with a Brembo.

I can only guess that the lever point on the original is set for really long travel. Modern Radial master cylinders just don't seem to move enough fluid.

@370 Steve has fixed his with a different Slave and Master combo, but not proven yet.

I'm keen to find an answer to this....

Help. 

That makes sense so! I'll be actively trying to find a solution anyways.. if I find something, updates will be posted 

[Upshotknothole]

This would explain why the 1000RR clutch MC I tried using years ago would never work. It looked good, but was useless.

[markfoggy]

The solution is probably using as RCS 19 , but £300 is a very expensive guess and I'm not sure who would buy one later, if it didn't work.

RCS16 seems to work with most bikes and there is a 17, which I guess might help in some applications. Bandit forums to the answer phone please. :lol:

Edited November 3, 2021 by markfoggy

[Damienga15de]

I used a zx7r master for my 7/11 build had similar issues with a ducati brembo cylinder when experimenting