Inconsistent Brake Pressure

Someone mentioned zip tying the brake lever overnight after bleeding the brakes over on the street triple forum. Opinions were divided as to the benefits of it but I guess if you think it makes a difference then it’s not a bad thing!

 

I have to say I have read about the same problem in the Spanish Triumph forum on the RS model.

maybe something is wrong from factory.

 

Tying the brake lever back and leaving the top off the master cylinder reservoir is something I have to do on my Suzuki Bandit (ABS model) every time I change fluid or renew brake lines etc. It makes a difference sometimes but not always. This particular model is very problematic when bleeding the brakes though. I also own a Street Triple and the front brake lever on that is rock hard.

 

Brake fluid does not compress but air bubbles within it do. They can exist anywhere in the system from top to bottom. Bubbles come in all sizes. You see the big ones but not the tiny ones.
Pinning the lever back pressurises the system which steadily forces bubbles out of suspension and causes them to rise - when the lever is released the accumulated air at the top then escapes via the refill gallery into the master cylinder and the brakes are fully bled.
Being able to pump the lever is itself an indication of compressible air in the system. Vacuum or pressurised bleeding is pretty sure fire but patience and gravity work well too if you dismount and rotate callipers to clear potential air pockets. Greasing bleed nipples with anti seize can also prevent return air leakage round the threads as can sometimes happen.

 

.......what @Callumity said....+1
Different purpose, but I have (work) experience of oil filling closed pressure systems, vacuum filling is the ideal way but leaving the system pressurised for a time with somewhere for the air to migrate is a close second.

 

I did this on my dirt bike but I opened the cap of my master cylinder reservoir before pulling the lever in. Seemed to help accelerate the process. Did you try that?

 

Cool. Could have been placebo to the task. That said it absolutely does work. I think if you have poorly bled brakes it may take longer or not work but for a few bubbles it works. Oh works ok mountain bike brakes too

 

I've done the tying the lever back against the handlebar method several times and it does work. However, I wouldn't take the top off the brake fluid reservoir as brake fluid is hygroscopic i.e. it absorbs water from the atmosphere - not good! Better IMHO to keep the system closed to the air.

 

On my Speed Triple I remove the calipers from the forks and rotate them so any air will either rise up the pipe or can exit the bleed nipple when bled
The master cylinder has a bleed nipple and sometimes I remove the brake lever assembly from the handlebar and rotate that too so any air can exit via the reservoir route
Sometimes using bungee cords to hang the assembly as vertical as possible to enable micro bubbles to rise up, this is more critical for rear brake systems

 

Not quite sure where the humour value was in my post, but glad it made you smile

 

You’re doing it wrong. Just hold the bike upside down.

 

No probs, just thought I had missed something...I hate air in the brake system and whenever I change brake fluid, service the calipers I go through this so I get the best feel possible through the brake system