Question on front brake reservoir

I was doing some maintenance yesterday and decided to check the front brake fluid. Based on the site glass, I was concerned that it was over-filled since I never saw a bubble when turning the bars. When I opened the cover, I found a white piece of what appeared to be foam floating in the reservoir. It's cutout as if it was designed to fit and was wondering if this was something Honda added after 2006? My 2006 ST didn't have this. The service manual that I've got is for the 2003-2006 models and doesn't show anything below the rubber diaphragm.
Thanks in advance.

That was added in 2008. It floats on the top of the pool of brake fluid to cut down on the amount of it that's exposed to the air.

There isn't one on the rear reservoir or the clutch, and I have no idea why not.

--Mark

Blrfl said:

That was added in 2008. It floats on the top of the pool of brake fluid to cut down on the amount of it that's exposed to the air.

There isn't one on the rear reservoir or the clutch, and I have no idea why not.

--Mark

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I have heard various stories over the years about the foam inside some mastercylinders. I've heard that its there to take up air space, I've heard that it was inserted before shipping to protect the diaphram,
I've heard it was missed and not removed during the final assembly process, etc.
I've often wondered if it was there so soak up condensation into the foam pours?
Anyone body really know why some bikes have them and some don't?
IGF

Thanks for the info. I checked on the OEM part drawings at Bike Bandit and the float is shown so I guess it supposed to be there! Strangely, it's not listed for the clutch reservoir. I would have thought you would also have included one there since it's a similar design.

mpawl99 said:

Thanks for the info. I checked on the OEM part drawings at Bike Bandit and the float is shown so I guess it supposed to be there! Strangely, it's not listed for the clutch reservoir. I would have thought you would also have included one there since it's a similar design.

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It could be because the folks who made the micro fish didn't have any more of a clue than us LOL.
Perhaps the folks assembling the bikes removed the clutch side when adding fluid, but forgot the brake side, and the rear mastercylinder.
The question continues.

Could it be there to show in the site glass if the fluid gets low? May be much easier to see than an air pocket.

Could it be there to show in the site glass if the fluid gets low? May be much easier to see than an air pocket.

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There's a metal backing behind the site glass that reflects light so you see the fluid better. (This also makes the fluid look clearer than what's in the reservoir.) Can that foam piece be seen behind that backing?