Bandit 12 Clutch issue

[Mr Hammers]

My lad's got himself a tidy little Bandit 12, but is having no luck sorting out a recurring problem with the clutch.

The problem is that he bleeds the clutch, everything is fine, biting point near the initial pull point, all works as it should. But after a short while, the biting point gets closer and closer to the bar, until eventually when in gear it starts creeping forward again.

He's changed the pipes/tubes/cables whatever they're called, he's changed the slave cylinder, and fitted a new master cylinder repair kit.

There are no leaks at the slave cylinder end, none on the cables...lines, that's what they're called, lines, but fluid is making its way out of the top of the master cylinder.

It's got to be something pretty simple, but we're both at a loss to what exactly is going on. My suggestion is that maybe the rubber membrane has a hole in it, and that he should try swapping the brake master cylinder one for it, and see if it still does it, which he's going to try next, or something to do with the little hole being too wide to fully seal..but i really don't know.

In the meantime, anyone have any insights?
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A Guide To Powerbands

[Nobby the Bastard]

[Mr Hammers]

Leaking out of, in that the cap is on, as normal, and it's leaking out of there. I imagine something is happening that is causing the pressure to build up on the wrong side of the system, but why i don't know.
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A Guide To Powerbands

[Nobby the Bastard]

Picture?
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Mr Hammers]

Not sure it'll help much, but..

https://www.planetash.net/bcf/leakymc.jpg
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A Guide To Powerbands

[Nobby the Bastard]

Now that is wierd.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Mr Hammers]

Isn't it? It's doing my bloody head in. He hasn't had chance to change the membrane (or try the brake MC on it as i've suggested) yet, but he had a quick look at it today, and it's back to normal.

That's not to say it won't lose pressure and do the same thing after a few miles.

Would an oversize little hole somehow cause it? My old NSR had a blocked little hole, and the problem was the opposite, in that the pads just kept getting tighter on the disk.
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A Guide To Powerbands

[Nobby the Bastard]

I think you may have two issues.

1) master cylinder seals are knackered. This would explain why you have to keep pumping up the lever to action the clutch.

2)The top isnt sealed correctly, quite possibly the membrane has more than a hole in it.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Mr Hammers]

[jaffa90]

[Mr Hammers]

Ok, so we're all agreed that that is probably what it is then. So, replacing the whole MC with another should cure the problem...shouldn't it?

Except, of course, it hasn't!

He's got himself another (used) clutch MC, fitted it, bled it, aaaand the same problem is still there.

I have NO idea what's going on. Maddening!
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A Guide To Powerbands

[Mr Hammers]

Ok, an update on this as we're completely at a loss as to what the hell is going on.

So far, he's replaced: Master cylinder, brake fluid, banjo bolts, clutch line, slave cylinder, clutch springs, clutch plates and friction plates....

...and it's still doing it. There's nothing else to replace!?

In desperation, he took it to a mechanic who spent all night on it, and still couldn't fix it. Gets up to pressure after being bled (been bled over 20x now) and as always, 5-10 miles later the pressure has gone again.

Hoping a Bandit 12 owner who has had this issue and fixed it sees this and can advise what it is..?

If not, anyone else have any ideas? Because i'm completely out.
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A Guide To Powerbands

[jeffyjeff]

Perhaps one or more of the master cylinder piston seals are installed backwards
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History shows again and again how nature points out the folly of men - BOC

[Evil Hans]

Get hold of a cable setup from a 600. Problem solved
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Triumph Sprint ST 1050. And it's Red.

[doggone]

Have a look where the clutch is activated under sprocket cover, there's a little push rod in there actually works it by pushing plates apart, and they are prone to getting gunked up with chain lube and grit.

[JackButler]

Pattern parts, Shenzhen specials from The Peoples Tractor Hydraulic Seal Manufacturing Co' ( we make other seals in our lunch break) Ltd.

£3.96 per set inc free postage from eBay, Wish, Wemoto, amazon, aliexpress, that bloke on facebook etc etc etc.
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I clean my guns with the tears of the snivelling, left wing scum.

[Mr Hammers]

[Riejufixing]

Is it true to say that:

1) It can be bled and is OK before being used on the road.

2) While being used on the road, the bite point changes until the clutch won't properly disengage.
3) If left parked overnight, it's then back to normal before it's used again, then goes back to 2.

If so, does it need more fluid adding from time to time, or not?


I'm just double-checking the situation in my mind.

[Mr Hammers]

Answers supplied by my lad;

[Riejufixing]

[jeffyjeff]

A quick parts search looks like the piston and cup are a single piece. Either the cup is leaking, the piston is damaged, or the bore is cracked or scored. Fluid is leaking past the piston/cup assembly and you are not getting a consistent full stroke through to the slave cylinder. When the lever is released, fluid that leaked past the cup is being pumped back up to the reservoir. May be time to break down and purchase a new clutch master cylinder. Believe you said the first one you tried was used... that one may have been replaced for the same reason.
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History shows again and again how nature points out the folly of men - BOC

[Pete.]

I wonder if it's the pushrods welded together. If the rods are turning with the engine then it might be generating enough heat in the slave piston to boil the oil.

Either way I would take a brake hose clamp with me next time and when this happens clamp off the hose. That will tell you if the problem is at the bar end or the slave end.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[carofmadness]

The cost for me is not an issue, and the play in the Conrod bearing is horizontal but more than I would expect. The problem is when it got stolen it was partially stripped so the flywheel and engine case were left off for a long time and the taper on the crank has some corrosion and the keyway is damaged as in the key moves from side to side about 1.5mm I. The keyway.

Personally I think I would like to recon the crankshaft just for peace of mind as I do not see myself getting rid of the bike, so any suggestions on a good place to get this done. I will be at my garage later today to take pics
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2018 Black Royal Enfield Continental GT 535 Single Cylinder (daily) : 1985 Honda CG125 (my first bike) : 2014 AJS Daytona 125 (my mums bike)

[Riejufixing]

[Mr Hammers]