You need to replace the hose and then bleed the system of any airbubbles. Make certain you use the exact same brand & viscosity of brake fluid to maintain consistency within the master cylinder. If you don’t know the exact kind of fluid, DRAIN THE SYSTEM AND START OVER W/ 100% NEW FLUID.
This should not be done “solo” for the first time by a novice (like me)…mistake in bleeding the line = your eyes HUGE as you hit the brake, it goes straight to the metal and you continue off the track onto the grass & dirt at an alamaring rate of speed. 😯
Contact any of the local shop owners…I’m sure they’d lend you a hand and sell you brake fluid…you’ll just need to bring your kart by their shop.
Best,
Troy