Failure? - 10/85, P30
From what I heard, the Venture seemed to be a little more susceptible to brake failure at the higher altitude of Steamboat Springs. (V-Daze '85) than say that of a Gold Wing. The Venture has about three
more feet of brake line than the GL does and some of it is metal.
The brakes themselves work on the principal that the fluid inside the lines, between the master pressure cylinder and the brake pad piston, does not compress. It only moves inside the line. When you apply pressure on the lever or pedal, it pushes the fluid through the lines and directly pushes the brake pads against the brake rotors, thus stopping the bike. If any air is in the line, it will be compressed as the pedal is pushed before the fluid can be moved, thus slowing the braking efficiency and causing the pedal to feel spongy.
For the flat land motorcycle, a small amount of air or a few bubbles will not make a noticeable difference until he rides to a higher elevation; Steamboat Springs for example.
At the higher elevation, the air is much thinner and the air pressure itself is much less. This causes the air in the brake line to expand and you now have a greater amount of air in the brake system to compress before you can stop.
DOT3 fluid has been used in cars since Columbus came over to Plymouth Rock in the ARK, and it is fine for cars. Most cars have a power booster on the master cylinder to apply a much more extreme amount of pressure to stop the heavier vehicle. This usually makes up for any air that may be in the system, be it not a great deal. DOT3 is also fine for motorcycles that are properly maintained. If the system is completely free of air, there will be no problem, but the slightest bit of air will be noticed at a higher elevation.
The brake lines follow the frame to the master cylinder and are routed over the top of the engine, which is very hot, then down the front fork tubes where it is much cooler. The same with the rear line, which is exposed to the cooler air also. With part of the line rubber and part metal, and part hot and part cold, it is a very likely place for condensation to occur. Since condensation is moisture, which is water (H20), and water is two parts oxygen, you can see a problem here over a period of time if the fluid is not changed periodically.
DOTS is a silicone base brake fluid, which helps to resist condensation to a certain extent, so it is a little more effective on a motorcycle, but it is not needed in a car with a power booster. It's also not harmful to you pain, so if it gets spilled while being changed, it won't hurt any of the body parts.
Normal Yamaha warranty time to flush and bleed the front brakes is 1/2 hour and the same for the rear. This is not an item under warranty because it should have been done
before the customer receives the machine, during pre-delivery. If you want DOTS, or the brakes flushed you will probably have to pay for it unless the bike is very new and has very low mileage. That will be up to your local dealer. The charge is not that much and the advantages are great.
So, if your Venture doesn't know when to stop... a fluid change could solve the problem.