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Discussion Starter #1
I have bought used Street Triple 2014 already in this condition.

Lever is set to number 1 (out of 4) - hardest option. Still when I am breaking, first 2-4 cm of level play basically no breaking, then in last 1-2 cm starts to break, but it will easily touch the handle.

what was done:
- first I thought air is in the system - did the "tide the lever to handle over night" trick with no success
- then put it in the official Triumph to change the breaking fluid and check the break pads - no success - still same condition - to my surprise they didn't offer any solution.

I don't think I have leak or air in the system, because it is not better after complete change of the break fluid, nothing helped even temporarily.

It seems like very simple system, basic four pistons Nissins, everyone always recommend the bleeding, but I dont think this is my problem, any tips greatly appreciated, thank you.
 

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You may have a leaking master cylinder. Nothing but a part swap would repair that and it would explain an inability to get braking pressure.

Where are you located? Perhaps a local rider could troubleshoot with you.
 

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Discussion Starter #3
Thank you for the answer, yeah I am located in Czech Republic, so it is gonna be problem. I also suspect master cylinder, but what part would you swap, whole master cylinder assembly or maybe MC piston set could be enough?

Today I shooted video how much play the lever actually have: https://youtu.be/iJStKm4hpC8
 

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Looks like there is air in the system still. Un bolt the calipers from the bike and twist and move them about and give them a few taps, if you have standard brake hoses that go up and over the front mudguard air can get trapped here too so make sure you lift up one of the calipers higher than this to get any air to move into the caliper and up to the bleed nipple, then bolt them back on and bleed them through again.


Doesnt look like you have a bleed nipple on the master cylinder so what you need to do is after you bleed the calipers tap the lines a few times then put some rag under the hose bolt at the master cylinder, next you need to squeeze the lever while slightly undoing the bolt at the master cylinder so any trapped air will escape, be aware that some fluid will come out so close the bolt before the lever hits the bar and make sure you have rags down to protect the paintwork.

If you still have a soft lever you might need to change seals in the master cylinder or calipers.

You could also try reverse bleeding with a syringe and push fluid into the farthest calipers bleed nipple, this will cause any air to be pushed up to the master cylinder, however it will also push a lot of fluid into the reservoir so make sure its not full and the lid is on.
 

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Discussion Starter #5
Thank you for the reply. I think I understand the process very good now . I will try to investigate again today, I still think main suspect is master cylinder piston and / or seals in it. I will try to deassembly by myself and if I am successfull, then order the parts. Otherwise I would have to give it to the shop again.
 

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Discussion Starter #6 (Edited)
I think I confirmed yesterday that it's the master cylinder piston in the problem. Dust cover has marks of the leak. But inside no signs of the actual fresh leak. Unfortunatery I couldn't deassembly completely because I don't have proper pliers to release safe seal.

I am still not 100% sure where is the air leak. My friend pointed out it could also go through ABS system and for bleeding the ABS system you need diagnostics connected (based on the manual).

So I decided to put it in the shop :| will post the results afterwards.
 

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Discussion Starter #7
Last update and solution. I had master cylinder piston changed at official Triumph servis and they also did again "lever to the handlebar" trick (which I am stunned they do as they are or should be professionals).

After piston change I could feel noticeble improvement, but I pointed out that still it is not how I am used to from other bikes and it should be on sportbike like this.

After consulting with the best mechanic, he could spot that lever is slightly bent (1-2 cm), propably some previous damage was done to the bike/lever. After changing the lever for the new one I am now now satisfied and I think now the problem is fixed.

Summary:
# changed master cylinder piston and seals
# break oil changed and bleeding the brakes (also "lever to the handlebar" trick)
# change of the brake lever (old was bent slightly)
 
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