[Rodman]

Hi everybody i own a 749s 06 model a long time now and recenlty I went on a race track to see the potentials of my bike. I have to say its a small track with 4 points of braking hard... Imagine that timer records around 1.20 per lap... So after 3 rounds I come of the last turn to the long straight and when i tried to brake of 200km p/h nothing !!! no brakes... The fluids where brand new the procedure of taking of the air from the system ( exuse my english I am from greece and I dont know how its called ) was done corectly on the main service of 10.000 km... the motorbike now has 11.000 .... what can possibly have caused that ? The brake fluids I used is Motul 5.1 ..

thanks for your help...

 

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What happened at the end of the straight, arriving with no brakes? Did you crash or was there a run out?
As to your problem; did the brakes return to normal later on and what brake linings were you using. If the brakes now operate normally, the likely cause is heat, either of the brake fluid or lining fade. If the fluid was boiling, the lever would have gone soft, if brake fade (of the pads) the lever would still feel the same, there just wouldn't be normal braking action.

 

[marxred749s]

I don't know about the motul 5.1 but I ride the hell out of my 06 749s on the track and after 40 minutes with standart dot4 very very little fade if any. If he didn't lose fluid and the 5.1 is compatible, A fluke of a master cylinder failure??

Really doesn't add up in my book.

Mark

 

[Bella749]

Were your pads worn out? I've never had any brake fade problems.

 

[Rodman]

the lever went soft the guys around told me that the fluids where overheated as a results of causing bubbles... we took the bubbles out and everything came back to normal...

Yes there was a run out no problem caused or crash... with the bike...

From other drivers that where at track told me that its common to overheat the brake in this track since it has to much braking hard in a small distance and you have to be carefull about it...

has anybody had similar problems ?

 

[jspecracer]

Dont know abou the Motul fluid, but check the heat ratings for boiling point on the bottle... you may want to step up to a fluid with higher ratings.

 

[Matt_P]

the lever went soft the guys around told me that the fluids where overheated as a results of causing bubbles... we took the bubbles out and everything came back to normal...

Yes there was a run out no problem caused or crash... with the bike...

From other drivers that where at track told me that its common to overheat the brake in this track since it has to much braking hard in a small distance and you have to be carefull about it...

has anybody had similar problems ?

Σε ποια πιστα ησουν; Μετακομιζω στο Ηρακλειο σε ενα μηνα και θα φερω την 1098s μαζι μου. Μαλλον θα σε δω στα track days.

As far as your problem goes, if your lever went soft and then you bled air from the system in my opinion it means that either the air was incorrectly bled at the service (most likely), or the fluid was no good. You could also have a failed front brake master cylinder.

Getting all the air out of the braking system can be quite tricky. I like to bleed the system from both the calipers and the master cylinder, then top the fluid level up and leave a rubber band on the brake lever over night to keep pressure in the line, which tends to cause any remaining bubbles to rise to the bleeding screw.