Master cylinder size

[speeding_ant]

After identifying an issue with my front master cylinder, I need it replaced. Currently it is 12mm, and I've been told a 14mm will give me more power with the 4 piston caliper.

Will I still have decent modulation if the bore is bigger?

(trying to use technical terms. If I'm wrong, don't blame me, I'm a noob!)

[bogan]

A bigger master diameter piston will give you more flow, but less fluid pressure. You'll have to put more force on the lever to stop as fast, but the lever won't move in as much.

I can see no reason why you would want to do that.

[unstuck]

Me neither.

[Kickaha]

Will I still have decent modulation if the bore is bigger?

No, with a 14mm a firmer lever and less travel is what you will have

why cant you rekit the exisiting m/c?

[speeding_ant]

No, with a 14mm a firmer lever and less travel is what you will have

why cant you rekit the exisiting m/c?

Yeah, that'll be the first option.

I'd rather have more modulation.

[bogan]

Yeah, that'll be the first option.

I'd rather have more modulation.

What is this modulation and how does it relate to M/C size?

[speeding_ant]

What is this modulation and how does it relate to M/C size?

The ability to control the brakes linearly within the lever action. Eg, not touchy. I figure a larger M/C means less modulation as it's moving more brake fluid to the calliper. I'm just not sure how much change 2mm will have.

[bogan]

The ability to control the brakes linearly within the lever action. Eg, not touchy. I figure a larger M/C means less modulation as it's moving more brake fluid to the calliper. I'm just not sure how much change 2mm will have.

Sounds more like spongy lines tbh, I much prefer 'force-only' braking where the movement of the lever between light and heavy braking is virtually non-existant, so the feedback on force applied is greater.

A 12-14mm jump will be 36% more force required, and 36% less lever movement.

[speeding_ant]

Sounds more like spongy lines tbh, I much prefer 'force-only' braking where the movement of the lever between light and heavy braking is virtually non-existant, so the feedback on force applied is greater.

A 12-14mm jump will be 36% more force required, and 36% less lever movement.

Cheers for the info. Master cylinder is getting looked at for much more serious problems - but for the price of a seal kit I could get a new larger M/S. If it's not just a blockage, then I'll need to decide what to do.

If it means I can brake with less fingers on the lever then I'm happy with that. Less lever action isn't a big problem - there's a fair bit of that at the moment.

As long as it won't adversely affect control, I'm happy.

[bogan]

Cheers for the info. Master cylinder is getting looked at for much more serious problems - but for the price of a seal kit I could get a new larger M/S. If it's not just a blockage, then I'll need to decide what to do.

If it means I can brake with less fingers on the lever then I'm happy with that. Less lever action isn't a big problem - there's a fair bit of that at the moment.

As long as it won't adversely affect control, I'm happy.

Bigger m/c diamter means exactly the opposite of that! Haven't you been reading what has been posted?

[speeding_ant]

Bigger m/c diamter means exactly the opposite of that! Haven't you been reading what has been posted?

Ah, right. Misread/understood.

Cheers

[Grumph]

Cheers for the info. Master cylinder is getting looked at for much more serious problems - but for the price of a seal kit I could get a new larger M/S. If it's not just a blockage, then I'll need to decide what to do.
.

Not true in my experience. "New" M/c cost much more than a seal kit and anything you can find cheaper will probably need kitting anyway.

Try Don at pitlane in Darfield. He's got a very big kit range on the shelf and is open weekends.

Edit - just saw Wgtn....give Don a ring anyway, he'll do mail order.

[Hugo Nougo]

What is so majorly wrong with your m/s that a complete redesign of Mr Honda's brake system is called for?. You're sure it's not just glazed pads?. I have some good second hand m/s in both 12 and 14mm if you want to try before you commit hard cash. my 320mm single disc 6pot with a shorty lever use's a 12mm m/s and it bites quickly and progressively.

[Owl]

I can see no reason why you would want to do that.

Was a recommended fix for my Speed Triple (5/8 from 14mm). Reason for not going back is more consistent lever travel. Feel is compromised somewhat (wooden), but I no longer have to remove/clean my calipers so often.

I can still brake with one finger, but then I do have big fat sausage fingers.

[speeding_ant]

What is so majorly wrong with your m/s that a complete redesign of Mr Honda's brake system is called for?. You're sure it's not just glazed pads?. I have some good second hand m/s in both 12 and 14mm if you want to try before you commit hard cash. my 320mm single disc 6pot with a shorty lever use's a 12mm m/s and it bites quickly and progressively.

The calliper seizes up after a run on the motorway -> Paekak hill. M/S needs a rebuild, though have also been offered a new larger Nissin M/S for not much more than the rebuild (cheap).

I've already figured out the solution based off the helpful responses here.

Cheers