$50 modification thread

[ChicagoBob]

My sub-$50 mods so far:
Coil relay
stainless brake line
steering head bearings
mini turn signals
H-4 headlight
heated grips w/ relay
rattle can paint and number graphics
new taillight
new headlight ears
new exhaust (used, but very nice)
new eBay seat and rear fender

That's about $500 so far.

 

[Normk]

Colin, I was intending to point out that your photo was upside down until I saw the Aukland location.

There are two holes connecting the master cylinder reservoir and the piston bore. The larger one to which you refer is the "Compensating Port" while the smaller one is the "Breather Port". Both must be open in order for the cylinder to operate properly.

The Breather Port's function is to allow fluid displaced by the return of the piston to move into the reservoir and to return when the piston moves forward in application. This "breathing" in and out of fluid through the port is the reason for the port's name. A plugged breather port can cause slow return of the piston/slow release of the brakes and/or encourage the entry of air past the cylinder's end seal. These can be difficult to diagnose if one does not recognize the presence of the port or understand its function.

The Compensating Port is intended to compensate for changes in brake fluid volume within the acting portion of the hydraulics. When the pads wear, for example, fluid from the reservior fills the void in order to provide automatic adjustment. When the brakes are in operation and the resulting heat causes the fluid to expand, for example, the fluid displaced during expansion enters the reserviour in order to avoid pressurizing the system and causing the brakes to drag.

Your post is an excellent piece of education for many users as they will likely not be aware of the need to check the slack in the mechanical linkage as part of maintenance inspection. Just another item we used to see wrong with owner maintained machines.

Your solution was an excellent one as was your advise regarding the use of a robust material as the spacer. Using something which would compress would lead to a spongy brake and limited effective stroke in application.

It would be well not note that having too much slack in the mechanical linkage as Colin corrected limits brake application. On the other hand, not allowing the piston to move past the port on release will cause brakes to drag!

The dragging effect can be more than minor as spacing the piston too far forward can result in having the brakes continue to self apply until wheel lock-up has occurred. We don't need to outline the risks there!

Ensure that both ports are open when checking master cylinder operation as part of yearly brake fluid change. Take care if using a tool through either port because a tiny burr on the inside edge of the port is likely to cut the piston sealing cup.

Excellent post, Colin! It should be very useful to some members.

Norm

Cheap fix $0.00 for excessive brake lever travel.

I had about 25% lever travel before the front pads would come into play. Bled them 100% but no real difference.

When bleeding them I noticed that a big jet of fluid would shoot up through a small pressure relief hole (designed to prevent expanding fluid from locking the brakes on).

I realised that the brakes weren't engaged until the piston seal in the MC passed over and blocked this hole and that was where the bulk of the excess lever travel was going.

I cut and hand machined an aluminum spacer (tried plastic but it dissolved) sized to allow about 5 - 10% max lever travel before the piston seal covered the hole and the fluid stopped squirting out (making for faster build up of pressure to activate the calipers)

Best mod I have made period (along with new braided brake lines - also a good $50 mod). Two finger braking now