New hawk250 rear brake issue

[WWRAFTER]

Have a couple weeks on the bike and have had a problem with the rear brake since assembly. They haven’t held any pressure in the system even after the initial flush. On the first ride, the rear brake faded and would not stop the bike. While bleeding, it continued to push air out, even after several ounces of fluid. I suspect a leak in the slave cylinder (noticed brake fluid during assembly). What is the best way to rule out faulty seals and location. If I can figure this out I can have the part shipped out on warranty.
Thanks, Russ.

[Megadan]

Do you still find any wet spots on the braking system after riding? If it introduces air while simply bleeding, and it is indeed a leak, it shouldn't be too hard to locate said leak.

Otherwise, the fading out while riding can also be caused by the rear brake adjustment. This is a common issue with new bikes. If there is no free play in the pedal then it will put a tiny bit of pressure on the brakes. As you ride the brakes will rub and slowly heat up, eventually leading to brake fade.

[ben2go]

Bad crush washers on the banjo fittings will leak and also allow entry of air into the system. A little piece of grit in the master cylinder will also cause brake fade or loss of pressure like the system is full of air. I am experiencing that on my current bike. I need to tear it down and clean it out. I just don't have time to fool with it.

[WWRAFTER]

I have not noticed any brake fluid after riding, but I’m not sure I could tell, the bike has been getting pretty wet from the riding terrain. I have the brake pedal adjusted with quite a bit of travel (I’m adjusting it at the master cylinder), although it doesn’t start actuating the brakes until almost to the end of the pedal travel.

[WWRAFTER]

Bad crush washers on the banjo fittings will leak and also allow entry of air into the system. A little piece of grit in the master cylinder will also cause brake fade or loss of pressure like the system is full of air. I am experiencing that on my current bike. I need to tear it down and clean it out. I just don't have time to fool with it.

Any idea where to source the crush washers? Air is definitely getting into the system, no matter how much I bleed it, I’m getting air pushing out the bleeder valve on each cycle.

[ben2go]

Any idea where to source the crush washers? Air is definitely getting into the system, no matter how much I bleed it, I’m getting air pushing out the bleeder valve on each cycle.

Any auto parts stores will have them. Take in your banjo bolt for the brake line to get the right size. I think they are 10mm. I prefer the copper ones but the aluminum ones work well.

I don't know what fluid you are using but I use Valvoline DOT3/4 and it works well. It seems to bleed easier than moto spec brake fluids. It could be all in my mind too.

https://i.walmartimages.com/i/p/00/07/41/30/79/0007413079087_500X500.jpg

[Azhule]

Mag 1 makes a really good DOT 4 brake fluid too, keep an eye on amazon to pick a case of them up for cheap

[WWRAFTER]

Thanks guys. Going to be a couple day soon before I can try anything else out. Thanks for the info Ben.

[ben2go]

Thanks guys. Going to be a couple day soon before I can try anything else out. Thanks for the info Ben.

You're welcome.