Crf450 rear master cylinder

[zcarlson12]

I’m having trouble getting mine bled. It will not build pressure at all. New line, caliper rebuilt and brand new master cylinder. I’ve been wanting to use one to get rid of the hose and mounting to the air box. Has anyone who uses one had the same issue? Pedal throw too short? I didn’t see anything in a search on here. Thanks for any help.

[croat1]

I’m not running that setup but here’s a few questions for you….

Are you bleeding it on the quad? Bench bleeding the system?

Is the pushrod long enough?

Joe

[2ndmoto]

Air can get trapped behind the caliper pistons. Make sure to press them all the way in before bleeding your brakes

[gentner8]

I had a stubborn jeep clutch I couldn't bleed.  I ordered one of these, and I wish I would have done it sooner.  Hook it to a compressor, and pull the handle to bleed, and tighten the bleeder.  The other bottle is filled with fresh fluid, and self feed the reservoir until bled.  That was a small master cylinder, but I have never used it on a bike.  I will be swapping my brake lines soon enough, and will try it.  https://www.amazon.com/gp/product/B08GM9GSZ1/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

[zcarlson12]

Joe, bleeding it on the quad. Swingarm is relaxed without the shock on so it’s feeding it down to the caliper. I’m starting to think the pushrod is not long enough.

2ndmoto, I’ll check but I thought they were all the way in, thanks for the tip.

gentner8, I’m using something very similar hooked up to an air compressor. First time using it and it bled the fronts in less than a minute.

[broken1]

I read somewhere about pushing the fluid in from the caliper up to the MC but never tried that method. Could be worth a shot.

[croat1]

I still wonder about braking issues due to hard use when doing the CRF conversion.  Zak, I’m assuming this is what your setup looks like.

Joe

[croat1]

What I’m getting at as far as my “hard use” comment is the system capacity.

Joe

[zcarlson12]

broken1, worth a shot thanks for the tip

Joe yes that is it. I wanted to get rid of the hose so I thought it would be pretty easily swapped out. Turning out to be the other way around lol.

[zcarlson12]

Here’s a picture without the pedal on I’ll get one later today with it on.

[sameltoe]

Mike's custom machine is who I had make that bracket in the above pic. Easy swap after that. They are a pain to bleed tho. Mike also made me a threaded washer that goes on plunger so you can have a return spring that's self contained.