To Fix a Leaking Master Cylinder Cover...or not

[desertrefugee]

As most of you know by now, I recently acquired a nicely maintained '84 Aspy to add to my stable. It really needed nothing, so I've mostly busied myself adding some understated bling. :twisted:

One of the things I expected no drama from was a pair of nice, chromed handlebar master cylinder covers. Sheesh. I can't get them to seal and have been freaking out cleaning weeping brake fluid all week. I used the stock diaphrams and they seemed to conform to the new lids correctly. Finally after wiping still more weeps this morning, at lunch I rode home and put the stockers back on. Ugh. Well, I got back to work AND NOW THE CLUTCH COVER IS LEAKING WITH THE STOCK LID!!!

:YMTONGUE:

Have I lost my mojo or am I forgetting some trick? I don't recall ever even thinking about these things leaking.

It's almost embarrassing... :-

[neoracer]

almost sounds like the mc may be overfilled unless the seal has some micro holes also

[desertrefugee]

Yeah, I figure these are original equipment. Man, they only lasted 27 years. I musta gotten ripped off! I just got back from the Honda shop and ordered two new ones. Funny thing is, there's also another piece - sort of a "positioning frame" that should be in there, too. Mine were long gone. Ordered them, too.

$45 bucks!

Honda knows they're the only source around for these obscure items.

[ghostrider52005]

Something you might try. While helping my friend work on a 1200 he changed out the brake fluid as requested by the owner bled it out and put the covers on only to see that the cover weeped slightly. checked the screws which were tight but the weep persisited.
We took it loose made sure it was set on square and then tightened each screw down alternating from first one screw then back to the other back and forth a couple of turns at a time until tight to make sure the cover seated squarely with the same amount of torgue on each side and the weep stopped.

Not sure that will fix your trouble but it did work on that bike and one other also.

[desertrefugee]

Good tip.

Thanks!

[desertrefugee]

Well, my brain finally kicked in and I figured out why I was having a devil of a time getting these chrome covers to seal.

The recess that the diaphrams fit into on the chrome ones is much "deeper" than the "shallower" stock covers. The extra "depth" doesn't allow the diaphrams to compress enough to seal when mated to the milled surface of the master cylinder itself. I sacrificed the rubber perimeter of the old diaphrams and sort of "doubled" up and all is well...

Kinda hokey, but it worked.