Hello, had my MV F3 800 now for about 3yrs with no problems, went to Italy on it last summer and put it away for the winter. Got it out again recently and the front brake isn’t there when you press it. You have to kind of prime it first with a quick press, then let it go and brake again. The lines have been blead but no difference. It’s weird because I read a test from one of the motorcycle mags online and they reported this same thing. Anyway, just thought I’d post to see if anyone has experienced this. Thanks very much in advance for any help.

If the brake improves when you pump the lever several times, you have air in the system.
There are plenty of threads on the forum, or you might want to resort to YouTube for a video.
I suspect the culprit will be the master cylinder, which is easy to bleed if you turn the handlebars so it sits at an uphill angle. This helps the air bubbles to rise up back into the reservoir.

Good time to do a full flush of the old fluid to remove any traces of water too....

Thanks very much, I’ve already had them bleed though at my local shop. I’ll do it myself again for price of mind tho next weekend and see if that makes a difference, thanks again.

I have little experience with MV, bought a 2016 Turismo just this year...
But, does your bike have ABS or TC?
If so, you might try exercising the ABS. That is braking hard enough, mostly with rear brake, to encourage the ABS pump to run.
I would do this several times, then try bleeding the front brake again.

Just waiting to hear if this is an ABs bike or not.. as mentioned the ABS pump can get air in it, and make this problem. Dealer can prime the abs, and pump all the fluid from the system this way.

Here is a Technical Bulletin that pertains to ABS Rear Brake Bleeding, but the principle applies to the front also:

8645_Service Bulletin n° 189 - Rear brake bleeding procedure.pdf

Wow!
I can't believe they go through that dog & pony show at the factory during initial build.

Technology: just got to love it...

They won’t do this at the factory they will simply activate the ABS pump through software and it will self bleed like all other manufacturers. Interested to hear if third party software has this feature as well.

The factory probably uses a vacuum fill device and cycles the ABS pump at the time of fill. Vacuum charging is common assembly line process for cooling and brake systems.

The problem in the field occurs when air gets into the ABS module circuits. Front and rear ABS circuits are independent (even on combined brake systems), so using the rear brake to the point of ABS intervention will not cycle the front brake circuit.

The real problem with ABS systems comes with lack of maintenance and old deteriorated brake fluid. Hence Harley's latest recall to perform routine brake fluid flushes on all their ABS bikes...Their customers haven't been (won't pay?) doing it. BMW is really hard core on warning buyers to change their brake fluid at set intervals.


Any way..the OP's problem is air in the system...and the dealer didn't do an adequate job of bleeding it out. Many shops (techs) use a pneumatic bleeder (not the same thing the factory uses at all), which makes the job pretty easy and complete UNLESS they are running 120 psi line pressure (common line pressure in most shop air supply lines).

The air bleeders are supposed to run on 90 psi or less. When the tech uses 120 psi the speed of fluid movement will create cavitation and tiny air bubbles in the fluid, which then collect at a high point and cause mushy brakes a day or so after the bleeding was done.

I would try that with the rear brake but that bastard hasn’t worked since the first weeks riding. Every time I bleed it, it just cooks the fluid on the next outing and stops working again. I think the bike is fantastic but the brakes are driving me mad!!