Slave cylinder Jota

H

HLT

New member
Location
Jönköping, Sweden
Hello,

my first post as a new member of this forum.

I am from sweden, and have a 1000 Jota 1981 (180). I have been the owner of the bike for the last 20 years, but it has unfortunately been standing still for the last 10 years. I recently decided to wipe the dust of it, and get it back on the road. However, I have ran into a problem which makes me very confused.

When I tested the (hydraulic) clutch, it felt normal in the lever, but it didnt disengage when I a put a gear in. I didnt put much attention to it then, and left it standing in the garage. A few days later, I noticed a wet spot of hydraulic fluid below the bike. I disassembled the cover with slave cylinder, and could see that o-ring and dust cover were in bad condition. When I ordered new parts, I could see in the drawing that there should be an 8mm ball between piston and push-rod. (I can swear that there was no ball there when I took it apart.) A bit confused, I ordered o-ring, dust cover and 8mm ball for the repair. I replaced the sealings, and bled the system. When I try to assemble the cover again, it is not possible with the 8mm ball on the piston, I have a space of a few mm between cover and block. So it seems like there havent been any 8mm ball there before my repair..??

I have not ridden the bike very much since I bought it, but clutch and gear shifting has always been working just fine. Cover with slave cylinder has been welded, but I have no idea when and how.

Does anyone have any idea why it is like this? Do you think I can use it without the ball?

I am also a bit worried that I couldnt feel the clutch disengaging when I tested it, or is it normal when it has been standing still for so long?

Regards Herman
 
HLT said:
Hello,

my first post as a new member of this forum.

I am from sweden, and have a 1000 Jota 1981 (180). I have been the owner of the bike for the last 20 years, but it has unfortunately been standing still for the last 10 years. I recently decided to wipe the dust of it, and get it back on the road. However, I have ran into a problem which makes me very confused.

When I tested the (hydraulic) clutch, it felt normal in the lever, but it didnt disengage when I a put a gear in. I didnt put much attention to it then, and left it standing in the garage. A few days later, I noticed a wet spot of hydraulic fluid below the bike. I disassembled the cover with slave cylinder, and could see that o-ring and dust cover were in bad condition. When I ordered new parts, I could see in the drawing that there should be an 8mm ball between piston and push-rod. (I can swear that there was no ball there when I took it apart.) A bit confused, I ordered o-ring, dust cover and 8mm ball for the repair. I replaced the sealings, and bled the system. When I try to assemble the cover again, it is not possible with the 8mm ball on the piston, I have a space of a few mm between cover and block. So it seems like there havent been any 8mm ball there before my repair..??

I have not ridden the bike very much since I bought it, but clutch and gear shifting has always been working just fine. Cover with slave cylinder has been welded, but I have no idea when and how.

Does anyone have any idea why it is like this? Do you think I can use it without the ball?

I am also a bit worried that I couldnt feel the clutch disengaging when I tested it, or is it normal when it has been standing still for so long?

Regards Herman
Click to expand...
Hi Herman there is a good chance that the ball is still in that bore in the piston.
It is not uncommon for the ball to seize in there and wear a flat that may look as though it is the base of the piston.
The case has most likely been welded up as they crack between the slave cylinder and the case from the pressure of clutch fluid getting between them.
Take the ball out bleed her up and give her heaps.
 
Okay, I cant see how this can happen, but I must try to get it out then, or get a new piston. Will the stuck clutch plates loosen up when I get the machine running?
 
HLT said:
Okay, I cant see how this can happen, but I must try to get it out then, or get a new piston. Will the stuck clutch plates loosen up when I get the machine running?
Click to expand...
Maybe.
There are numerous posts on how to free stuck clutches without taking them to bits and cleaning the discs.
If all the various methods fail, you'll need to dismantle it.

Paul
 
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I have a proper repair system in place for the welded cover, if yours is not leaking fluid now, it will at some time do it again, welding the crack up is difficult because the alloy is barely 2mm thick at this point, it should be the reducing sleeve inside doing the work, not the cover, all this does is move the vulnerable area to alongside the weld, and off we go again, beg or borrow a copy of the last two ILOC magazines from someone who is a member and get a detailed read on how I can do this for you. Gunnar will have them, ask him to copy the articles and send them to you, if that fails ask me on "clemlav@tinyonline.co.uk"

your ball (which is one of two in the system, the other being between the two push rod halves inside the mainshaft) is "crimped" into the base of the piston, not easy to get it out but new pistons in anadised alloy can be bought from Redax in Australia or stainless ones from Motalia in UK, both have new balls inside them that will rotate, you should not see a flat on the ball, and you should see a tiny indentaion on the end of the poushrod.

I have genuine dust seals in stock (Brembo) which are a lot better than the pattern one you have fitted, as far as I know this is the only stock of Brembo dust seals anywhere.

to free the stuck plates see previous postings, use the search facility.

CLEM
 
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HLT said:
Thanks for suggestion, but I doubt this is the case?

Regards Herman
Click to expand...
Yep that's the flattened ball you could just put it back togeather it will still activate the push rod if your plates are stuck thats another issue as Clem mentioned.
I have tried good thrashings but most of the time those old friction plates can have a glue like make up that is impossible to remove.
I have just replaced two clutch packs with Reds Kevlar plates to get rid of the stuck plate issue.
 
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To free them up once at least, get the bike running and rolling at a low speed, drop it into first then with the clutch held in give it some rough on/off the throttle transitions and it will almost always free up.
The only time I have seen this not work was at a certain address in Canberra Grove (not in Canberra) and the bike in question had been doing top gear burnouts the night before and had welded the entire clutch pack solid. Wasn't me! :D
The old plates may well stick again though, if it annoys you too much then new plates are in order.
 
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Thanks for all assistance, clutch is now fine with a new piston from Motalia.co.uk. Clutch plates sticking was solved quite easily, so that is not a problem anymore. However, I have other problems with carbs since I have converted to open bellmouths, but I must search the forum for info about that.
 
HLT said:
However, I have other problems with carbs since I have converted to open bellmouths, but I must search the forum for info about that.
Click to expand...
I never got my 74 to run properly on bellmouths and standard exhaust. Futzed with needle and jets but never pulled cleanly across the rev range. Airbox & standard jetting did the trick eventually
 
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