Ducati Monster S2R brake issue

[SemiPro]

I recently bought 2008 Ducati Monster S2R. So first thing I did was to get a Desmo service, after that it developed a recurring and dangerous issue, a feeling of clutch slip followed by complete rear brake lock up. My mechanic said it could be due to a long time idling. A second mechanic found and fixed stuck clutch plates. Though, the rear brake issue was still on, leading me to bleed it entirely. Now, the front brake has also ceased to work after a long day or riding on a hot and sunny day, suggesting a heat-related problem affecting both the clutch/transmission and the brakes. I'm stuck and need help diagnosing these failures.

 

[SZA]

I recently bought 2008 Ducati Monster S2R. So first thing I did was to get a Desmo service, after that it developed a recurring and dangerous issue, a feeling of clutch slip followed by complete rear brake lock up. My mechanic said it could be due to a long time idling. A second mechanic found and fixed stuck clutch plates. Though, the rear brake issue was still on, leading me to bleed it entirely. Now, the front brake has also ceased to work after a long day or riding on a hot and sunny day, suggesting a heat-related problem affecting both the clutch/transmission and the brakes. I'm stuck and need help diagnosing these failures.

Ooh, that sounds like a heat soak issue. It's the only thing I see that can explain the fluid expansion. You gotta check if the brake and clutch master cylinders or the lines are blocked. Should be possible. If you replace old lines with braided steel and do a full fluid flush, I think this can be resolved.

 

[Reagan1]

Man, your Monster's got a temper! Overheating could be boiling brake fluid, so check for moisture or old lines, you can also flush fluids, use high-temp DOT 4, and try steel-braided lines.

 

[guido]

If your new bike has aftermarket levers, the bleed-back screw may have been mistakenly used to alter the lever angle. If there is not a zero-pressure zone where pumped fluid can re-enter the reservoir it will heat itself up and lock the brake. If this is the issue, then releasing the trapped fluid by loosening the caliper bleeder will free the rotor, but the bleed-back screw on the lever perch will require adjustment, usually screwing it back in until the problem stops.

1978 R1050S
2002 ST4S
2003 ST4S
2007 S4RS

 

[thiago_tavares]

Could be more than one issue:
1. Older lines may have micro-cracks that can leak fluid and contaminate it with air.
2. The cylinder seal may be dry and cracked, keeping the brake and clutch partially engaged and damaging them. (aftermarket levers, sometime causes the same issue)
3. The caliper and servo cylinder seals may also be dry.

I have the first in my 2010 monster right now, I have to change the fluid on each 2 or 3 months, till I change the line, the two and tree I had in an old bike from Yamaha.
On an old bike it is good practice to change all the seals and lines once every ride, between 10 or 15 years is a good time