Bleeding Brakes, Guide me :)

[Thom]

Ok i tried to bleed my front discs on the GPX not long ago and although i used oldish brake fluid (half used botttle which had its foil seal broken for about 3months) the brake just feels really spongey and so im not sure what i should do.

It is simply just bleeding it needs as the master cylinder is mint and ive rebuilt both calipers now but how can i bleed the brakes up front, considering ive only ever successfully back bled a single disc bike.

Can anyone guide me, step by step, as to how to bleed twin discs?

cheers#
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Current Bike: 1996 Yamaha TRX850 (The Japanese-Ducati One).
Previous Bikes: 1990 Honda NSR125 'Rothmans' (The smoking one), 1990 Suzuki GS500e 'Caf? fighter' (The loud one), 1987 Kawasaki GPX400r (The quick one), 1997 XJ600s Diversion (The reliable one), 2000 Kawasaki ER-5 (The spontaneously combustive one)

[Ste]

[Thom]

I forgot about that!

Cheers man!
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Current Bike: 1996 Yamaha TRX850 (The Japanese-Ducati One).
Previous Bikes: 1990 Honda NSR125 'Rothmans' (The smoking one), 1990 Suzuki GS500e 'Caf? fighter' (The loud one), 1987 Kawasaki GPX400r (The quick one), 1997 XJ600s Diversion (The reliable one), 2000 Kawasaki ER-5 (The spontaneously combustive one)

[SoND]

Bleed it the same as you did the rear but one side at a time, it's not as hard as you think.

Have a read through these, there's a whole lot more threads if you use the search button.

https://www.bikechatforums.com/viewtopic.php?t=156424&

https://www.bikechatforums.com/viewtopic.php?t=127093&

https://www.bikechatforums.com/viewtopic.php?t=158107&
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[Thom]

Maybe i should furthur explain my confusion.

I have two front brake discs+calipers, however the hoses join half way up at a 'thing' and then its a single hose to the caliper. i cannot understand how on earth i can bleed this system.

And ive read the guides with little success
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Current Bike: 1996 Yamaha TRX850 (The Japanese-Ducati One).
Previous Bikes: 1990 Honda NSR125 'Rothmans' (The smoking one), 1990 Suzuki GS500e 'Caf? fighter' (The loud one), 1987 Kawasaki GPX400r (The quick one), 1997 XJ600s Diversion (The reliable one), 2000 Kawasaki ER-5 (The spontaneously combustive one)

[SoND]

A 'thing'? Any pictures of said 'thing'?

Are you getting any pressure in the system at all?
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Go back to bed - You have no rights - "Streetfighters ~ Mainstream motorcycling's crackwhore sister."

[Thom]

I dont have any pictures but what it is is a sort of cylinder which has the three hoses coming off. im guessing its there to split the pressure from a single hose form the master cylinder to two hoses to the calipers.

Im getting some pressure and the lever wont go to the bar, but its VERY spongey and feels nasty.
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Current Bike: 1996 Yamaha TRX850 (The Japanese-Ducati One).
Previous Bikes: 1990 Honda NSR125 'Rothmans' (The smoking one), 1990 Suzuki GS500e 'Caf? fighter' (The loud one), 1987 Kawasaki GPX400r (The quick one), 1997 XJ600s Diversion (The reliable one), 2000 Kawasaki ER-5 (The spontaneously combustive one)

[Thom]

[Barry_M2]

Take cap off your fluid res, top up fluid.

Attach hose to bleed nipple on caliper, and put the end of the hose in a jar to catch the fluid.

With a 10mm spanner, undo nipple 1/4 turn, pull lever in and tighten nipple, release lever.

Keep doing that, remembering to check and top up your fluid level in the reservior.

Once you done that 4 or 5 times, close the nipple, pump the lever til hard and hold it on, then undo the nipple and tighten. If there is still air in it, repeat until its all gone.


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[Thom]

Right lads i think ive bled my brakes ok, they feel about as firm as i got them yesterday so im still concerned, however i think these concerns may come from having braided hoses on the gs500 as they felt alot firmer.

I have a question which may help.

When pulling the lever as far as i can should the pressure feel constant and then the lever should stop and be VERY hard to pull any furthur or feel gradually harder to pull the closer to the bar it gets yet can touch the bar if two hands are used?

I think it could simply be the fact the rubber hoses expand when im pulling the lever, but for my own safety and my MOT id like to know what i should be looking for form the lever.
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Current Bike: 1996 Yamaha TRX850 (The Japanese-Ducati One).
Previous Bikes: 1990 Honda NSR125 'Rothmans' (The smoking one), 1990 Suzuki GS500e 'Caf? fighter' (The loud one), 1987 Kawasaki GPX400r (The quick one), 1997 XJ600s Diversion (The reliable one), 2000 Kawasaki ER-5 (The spontaneously combustive one)

[Mr Hammers]

If you need two hands to pull it all the way back i'd guess that is good enough, as you'll never be in a situation where you'll need to do that - at least i hope not!

It sounds like the lines are expanding, or it could be that you've used old fluid - apparently brake fluid is prone to soaking up moisture in the air left to its own devices..some people even cap the bottle in between topping up when bleeding.
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[Thom]

neah it wasnt old fluid, fresh out of the shop new dot 4.

I think what im going to do is just gather up a couple more opinions, as i have an MOT soon and if it fails the MOT i'll see if braided lines solve the issue.
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Current Bike: 1996 Yamaha TRX850 (The Japanese-Ducati One).
Previous Bikes: 1990 Honda NSR125 'Rothmans' (The smoking one), 1990 Suzuki GS500e 'Caf? fighter' (The loud one), 1987 Kawasaki GPX400r (The quick one), 1997 XJ600s Diversion (The reliable one), 2000 Kawasaki ER-5 (The spontaneously combustive one)

[Mr Hammers]

So long as it stops as it should, and is impossible to pull the lever back to the bar with one hand, i can't see you''ll have a problem getting it through, tbh.
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