Clutch not disengaging fully after hard acceleration

Hi all,

I’m a month or so into owning this wonderful machine. I recently changed out the brake fluid front and rear and in the clutch, which I figured would fix this issue.

After ripping it hard, the bike will occasionally fail to fully disengage the clutch, trying to pull forward slowly at idle. Any thoughts on fixing this? Note that the master cylinder reservoir has had a leak in the past at the seam of the cap as evidenced by the peeling paint. Also wondering why the clutch reservoir cap has this long rubber seal that dips deep into the fluid (causing spills) why the front brake reservoir has a rubber seal under the cap that is flat.

Best,
HysteriaGland

Poor design of the clutch reservoir. The thing that appears to be a bellows, is not. The brake reservoir does have a bellows, which seals, and allows the fluid level to drop as the pads wear. Just part of the Moto Guzzi charm I guess. Most of us live with it.

It would be interesting if the folks who've switched to a different clutch m/c would chime in and report whether they continue to have the fluid go dark so quickly, or it behaves like the brake fluid.

The seals have likely collapsed. If the clutch fluid isn’t changed at least yearly the seals will degrade and when asked to move swiftly in the bore will have a tendency to leak.

HysteriaGland wrote:

Hi all,

I’m a month or so into owning this wonderful machine. I recently changed out the brake fluid front and rear and in the clutch, which I figured would fix this issue.

After ripping it hard, the bike will occasionally fail to fully disengage the clutch, trying to pull forward slowly at idle. Any thoughts on fixing this? Note that the master cylinder reservoir has had a leak in the past at the seam of the cap as evidenced by the peeling paint. Also wondering why the clutch reservoir cap has this long rubber seal that dips deep into the fluid (causing spills) why the front brake reservoir has a rubber seal under the cap that is flat.

Best,
HysteriaGland

I was confused about this difference in reservoir cap seal design myself for quite a while as all my scooters with hydraulic clutch control have the same syndrome. If you will think about how the hydraulics work,in the case of the brakes as the pads wear down the pistons move OUT of the bores which requires more fluid to compensate for this volume in the calipers.In the case of the clutch as the clutch lining wears it pushes the slave cylinder piston IN to the slave cylinder which pushes fluid back into the master cylinder. So if my thinking is correct the brake fluid needs to be "full" & will go down as the brakes wear & will need for the cap seal to expand to compensate for the fluid movement to the calipers.The clutch reservoir only should need a minimal amount of fluid to begin with so that as the clutch linings wear & the slave piston is pushed back into the cylinder the displaced fluid will be returned to the clutch reservoir which will be "absorbed" by the long rubber seal that dips into the fluid. The fluid does need to be changed regularly but I don't believe that the reservoir needs to be filled the same way,i.e.as full as possible.

Brembo radial MCs don't seem to have the degrading colour (or fluid properties generally) - I haven't touched mine for three years at least & still clear.....I have separate Rizoma reservoirs connected with rubber pipe.

paulbrice wrote:

Brembo radial MCs don't seem to have the degrading colour (or fluid properties generally)

That wasn't/isn't my experience. It goes dark the same as the stock MC. Only took about 1 week.



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That rebuild kit for the M/C

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Good info, I’m looking at a winter refresh myself.