Need help troubleshooting rear brakes

[p5200]

I seem to have no resistance at all on the rear brake pedal and no rear brakes. They were pretty good before I removed the right side crank cover. In order to get to the lower bolts of the cover, I took a piece of baling wire and wired the pedal in the down position. I assume, that caused at least, part of the brake problem. I can't see where fluid came out but, I did have to add more fluid. Added the fluid but still no resistance to pedal. Should I try to bleed the rear brakes? Thanks

[Mech]

You could and it might be ok for a while but it's a sign something's leaking. You probably need to bleed it to find the leak though so it might as well be done.

[Gwbarm]

I thought the rear brakes were spring actuated with a rod going to the hub arm from petal , no master cylinder for rear, unless im understanding wrong, only mater cylinder for the front, this is for your 2000 300 right. There are wing nuts on the end of the rod from the petal to adjust brake tension  and cable going from the hand lever to rear brake.

[p5200]

This is the trx300ex and it does, have disc brakes on rear also. I was kind of surprised myself when I found out it had disc on front and back for it's price range. I'm going to wait for a warmer day and try, bleeding the brakes. I guess it would be easier to get someone else to help. Thanks guys! 👍

[p5200]

Any idea, what size hose I would need to slip over bleeding nipple to bleed my brakes?

[p5200]

you tube I watched said use an 8mm wrench if that helps any. Didn't say what size hose though.

[Gwbarm]

Sorry about that I looked up the TRX300 and this is what I found yours must be a fancier model:

 

I usually use aquarium hose but its probably 1/8-3/16 inch.

[p5200]

My wife has a lot of oxygen hose I might check that first.

[p5200]

This is what mine shows   

[Gwbarm]

For finding the leak if you don't see any thing obvious along the brake lines, look at the caliper closely to see if you see any there, if not just  put in fluid and bleed them like mech said, see if you get some pressure, if you don't see fluid leaking and it doesn't build up any pressure, check to see if your fluid is still topped up, if it is master cylinder is not functioning. 

[p5200]

I've got a feeling, it probably is a bad master cylinder but I'll try bleeding to make sure. Glad I found my shorted wires that were melted together inside the split wire loom. My headlight would blow a fuse when switch was flipped. Also, my battery was discharging instead of charging when running.

[Gwbarm]

That good you found that, electrical problems are sometimes hard to find, the joys of fixing old neglected ATVs, at least your making headway, im still trying to get mine to spark, and its gotten cold and Rainey here, not much work going on today.

[p5200]

Yeah, that Big Bear sounds like the cdi is pretty tricky compared to the Hondas. I've been looking online for any pin out specs and any static tests that might be made on the cdi but, haven't ran across anything yet. Hopefully, you'll be able to get that going and maybe, not have to spend $400.00 for a cdi.

[Pod]

On 3/17/2023 at 10:09 PM, p5200 said:

I seem to have no resistance at all on the rear brake pedal and no rear brakes. They were pretty good before I removed the right side crank cover. In order to get to the lower bolts of the cover, I took a piece of baling wire and wired the pedal in the down position. I assume, that caused at least, part of the brake problem. I can't see where fluid came out but, I did have to add more fluid. Added the fluid but still no resistance to pedal. Should I try to bleed the rear brakes? Thanks

Most likely a component that failed, hoses, master cylinder etc. Fill up fluid and try to bleed you’ll probably able to find the leak

[p5200]

I tried that and nothing came out the bleeder nipple and the reservoir so, I assume the mastercylinder is not pumping the fluid.

reservoir stayed full 

[Pod]

52 minutes ago, p5200 said:

I tried that and nothing came out the bleeder nipple and the reservoir so, I assume the mastercylinder is not pumping the fluid.

reservoir stayed full 

Look like you may have found the culprit

[Mech]

The master cylinder might bleed if you either take the hose off it and use your finger over the hole as a one way valve, or loosen the bleed nipple on the caliper and use your finger as a one way valve back there. Then put the hose back on and try bleeding it at the back wheel. It's also possible the piston s stuck down in the cylinder, in which case a bit of sharp tapping on the lever might free it, or you could blow air back up into it.

To bleed the caliper I would also put my finger over the nipple as a one way valve until the fluid got to the nipple.

[p5200]

Mission Automotive 16oz Brake Bleeding Kit - Easy Use One Person Brake Fluid Bleeder with Magnet Mount and Hanging Lanyard - for Car and Motorcycles Brake Systems 16oz Fluid Capacity https://a.co/d/7PiqBqV would something like this be useful?

[Mech]

Yeah, for catching the brake fluid if you manage to get some out. But you've got to get the fluid pumping through before that.