Topic: Master cylinder rebuild question

[5youngs]

I am rebuilding the master cylinder for my sons 1978 CB 550K and wondered if anyone had a picture of the pattern in which it goes back together? The exploded parts picture is a little confusing to me.

Thanks

[TwoTired]

Is the drawing on page 70 of the Honda Shop manual not good enough?
 You should be aware that part 8 goes on the middle of part 7.

Cheers,

[the_genrl]

in the following order:

1. check valve
2. spring (bigger end without the plate on the end first)
3. Primary seal
4. Secondary seal
5. piston
6. retainer washer
7. Circlip (this ones a pain in the ass)
8. dust boot
9. ring clip (holds dust boot inplace)

[5youngs]

I don't think there is a check valve, at least I did not see one when i took it apart. I attached a link to what is on my 78. http://www.powersportspro.com/partsfish/displayfiche.asp

[TwoTired]

I neve rreally understood the need for a check valve in any of the master cylinders.
I mean, check valves allow fluid to travel one way, right?

But, the master supplies fluid to the caliper one way.  And, when the caliper piston pushes back into the bore, the fluid has to comeback to the reservior, or the brake remains locked.  That's two directional flow, isn't it?

Maybe the check valve is a fluid speed damper for the return?

Maybe Honda figured out it just wasn't necessary.

[5youngs]

I got it!! I had to apply some brake fluid to the rubber seal/valves and it worked much better.

The picture on page 70 is different that what is on my sons 78. It is lacking the first check valve.

The piston does have a check valve on it. It is a like a reed valve design on one side.

Thanks again. Tonight we are going to hook up the carbs and see what happens.

Mark