Brake Lines full of air - new to karting


I’m still really new to this karting, and doing it for my two boys who absolutely loved the 2 times we’ve been.

I’ve brought a kart last year, and after leaving it standing for 6months the brake line is full of air. I’ve had a look online and on YouTube, but I can’t see anyone that has the same brake system as on my kids kart.
I’ve attrached a couple of images, if anyone could point me in the right direction I’d be HUGELY appreciative.

I’ll let more experienced guys chime in but seems to me you need to bleed your brakes. That flushes the air out. Basically, you unscrew a bolt cap on the master cylinder and attach a gravity fed brake bleeder. There’s a thing you unscrew on the opposite end, back at the caliper as well. This opens the system and allows the gravity to push the air out, replacing it with fluid. It’s a bit messy if you allow the brake fluid to get all over the place. It also is not good for your chassis paint.


Oh yeah, also make sure to not mix up brake fluid and mix different types. Others can advise better on what DOT fluid you might have in there.

This is it in a nutshell. The process involves bleeding fluid from the caliper side while adding it in on the master cylinder (MC) side. I recommend a brake bleed kit to make it easy to draw the fluid out into a drain container & alleviate mess. Be sure to confirm the compatible DOT fluid type for your brakes. Oils/fluids don’t mix & match.

Step 1: Find the bleed point on the caliper (It might be that hex cap screw over the smaller pot piston, next to the input brake fluid line in the 1st pic, but I’m not sure), & connect the bleed pump to it.
Step 2: Locate the MC fill point (Looks like the allen bolt on the top, right above the output brake line. You’ll need to thread on a MC filler like the one Dom posted.
Step 3: With the MC open & the bleed pump connected to the caliper, draw out the old brake fluid into a container for discard & then continue pumping & adding fluid to the MC, never letting it get empty, until the there’s only fluid (ie. no air) draining into to bleed pump container.
Step 4: Ensure the MC is topped off, close both ends of the brake system, & clean up (Shouldn’t be much of anything to wipe up).
Step 5: Discard the old DOT at a recycle place.

Game Over

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This one will be really frustrating to bleed - the line is connected to the caliper above the bleed screw. You may want to unbolt the caliper and flip it over so air can be taken out of the calipers.

You’ll want to buy or borrow a tower bleeder - it’s a bottle-on-a-stick that allows fluid to be put into the system with enough pressure head to make it through to the back of the kart readily.

TaG karts heat the rotor heavily enough to want good fluid (Castrol SRF if you don’t like to bleed it regularly, any fluid with a dry boiling point over 550F if you’ll bleed it before every big race). If it’s a 4-cycle or Yamaha Can you can just use Prestone DOT3. Before you fill the system with DOT3/DOT4, take a little sample of the fluid and mix it with a little sample of DOT3/DOT4 and make sure it’s miscible and not DOT5.

If your brakes leak down over the winter then they leak, period, and you should fix the leak before taking the kart out on track. Clean the brake system off then use a c-clamp around the brake pedal and front bumper to apply the brakes all night to find where it is leaking from.

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Thanks mate, I took the calliper off and flipped it so the bleed point was above the inlet. Worked like a dream. Thanks.

Brilliant guys. Thanks for all the help. All done and works like a dream again.