When I first bought my bike my brother was pulling the front brake lever to see how the MCS master cylinder felt and asked, why does the front brake lever have a much firmer feel on the second immediate pull. So in other words, squeeze the lever, release, then squeeze it again immediately. The second pull was much firmer than the first. Now you wouldn’t do this on the road, but it shouldn’t do that right? The bike was at the dealer still, so we tried the other RS and it did it as well. We also tried a few other bikes including 2 Street Triples, none had a stronger second pull. Before they delivered the bike they bled the lines but there was was no improvement . I read a Speed RS review by “Bike Me” and they said during the launch of the Speed Triple in Spain half of the bikes did this. Now it didn’t have a negative effect on how the brakes performed when I finally road my bike, but it still kinda bothered me. Recently my brother changed the brake fluid on his GSX S1000 and after bleeding them, he squeezed the brake lever firmly and zip tied it in place and left it for several hours. This is suppose to force out any remaining air in the lines back to the reservoir. Now he never experienced the same issue on his bike, but just wanted to make sure all the air was out of the lines. What he noticed was that the brake lever now had much firmer pull than it did before he zip tied it. This got me thinking, maybe that might help with my issue. So I thought what the hell, I’ll give it a try. After about 2 hours I released the lever and guess what, the inconsistent pull was nearly gone. So it went back on for a few more hours, and now it almost undetectable. Again, I know it didn’t have a negative effect on the brake performance when riding the bike, but I’m happy I’ve virtually eliminated it. Anyway sorry for the long rambling, but I thought I’d share my experience.
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!
Yeah, made a night and day improvement. Firmed up the pressure and got ride of the large difference between the fist and second pull. But it may not have the same effect on every bike I suppose. If others have tried it with no discernible difference, then other factors might be at play as well.
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?
No. This idea came from my brother watching this video, this guy seems pretty knowledgeable. In the video he doesn’t crack the cap of the reservoir. Reservoirs will always have air in them, so opening them doesn’t seem necessary, but I’m no expert, that’s for sure .
Yes, I own a Street Triple with a Nissin Brake system and it’s hard as well. No inconsistencies from first to second pull. The MCS master cylinder may be just finicky to bleed. Or maybe it’s the engineering of the brake system on this particular motorcycle that can lead to this issue. I’d be curious to see how many of our bikes on this forum have the issue I had. Check your bike fellas and post the results .
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
My apologies sir. When I thought you were poking fun of this process, as some think its hocus-pocus, you were actually taking it to the next level of perfection. Every day is a school day.
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
