[caveeagle]

I have a 2015 CF800 that has a single rear brake caliper located in front of the rear diff.   I broke a rear hydraulic line.  Had a local shop make a new rear line.  Now I cannot get it to bleed properly.   I tried using a vacuum bleeder with no luck.

I tried removing the hose from the caliper and covered the banjo with two fingers to see if I could feel pressure and maybe force bleed the line before reconnecting it.  No luck with that either.  I can feel a small amount of pressure when pressing the foot brake pedal but no luck getting any significant fluid to bleed.

Is it time for a new rear master cyl?   Or is there some bleeding proceedure that I am missing?

This ATV is a 2015,  but has less than 350 miles on it, and has never been submerged or beaten up on too much.. so I am a little surprised if the MC is shot already.

[NMKawierider]

Those have an odd system where the foot brake and the right hand brake pressures both the front and rear brakes and the left only pressures the fronts. On the rear master there is two lines-the rear most line goes to a "T" with a check valve(I think) that pressures the front calipers and the front-most line on that master pressures the rear caliper. There is an odd bleeding procedure but I forget what it is. Most people reverse or back bleed these making sure the reservoirs are kept full as I recall.

[caveeagle]

Bump..   Anyone see this issue before?

Update:  I have a new master cylinder on order.  Just looking for a little more insight on this..

[caveeagle]

Those have an odd system where the foot brake and the right hand brake pressures both the front and rear brakes and the left only pressures the fronts. On the rear master there is two lines-the rear most line goes to a "T" with a check valve(I think) that pressures the front calipers and the front-most line on that master pressures the rear caliper. There is an odd bleeding procedure but I forget what it is. Most people reverse or back bleed these making sure the reservoirs are kept full as I recall.

From the diagrams I can find, there may be two systems.   On my CF800,  the front calipers have two lines running to them.  I need to confirm the line routing, but it seems like one set of lines is pressurized from the hand lever brake.  And the other set of front lines is fed by the rear MC/rear port.  whigh is the same one that has the sending unit on it. 

It is hard to see how the hydraulic line routing runs around the steering box/linkage, but I will dig into it today.   

With the new MC, I am able to get the rear-MC front circuit to pressurize and push fluid through the lind.  But so gar the rear port is not primed and pushing fluid yet.

I suspect, I need to crack open one (both) of the front caliper bleeders to get fluide to prime and bleed the fronts.  *I am assuming the front calipers have two separate bleeders??   Have to check on that.

[NMKawierider]

Yes, if you have the system that the foot brake applies pressure to both the front and the rear, the fronts will have two separate pressure chambers in each caliper with two separate bleeders. The line routing may be like this:



IF not, this is the other way it can be:

[caveeagle]

I think you are correct.   Taking a closer look at the front calipers, there are definately two bleeders on each side.   I don't think there is room to get my vacuum bleeder onto the rear(foot) circuit.

I din't have any luck trying to bleed just using the old pump/crack the valve method.   Now I am thinking of trying to fab up a pressure bleed system.   I have the reservoir cap off the old rear master.  I could try to add a barb fitting and apply some pressure from a bike pump...   Seems odd that I cannot find any youtube videos or any other info on this.

[NMKawierider]

Most people reverse or back-bleed ones like this. It pushes fluid through the bleeder and back up to the master. Air likes to rise anyway. Just have to pull the master's fluid levels down some before and get ready to take more out as you bleed. Just mane sure the plunger is completely retracted and there is some free play on the peddle..just a touch.

[caveeagle]

Can anyone explain to me how the Front/rear brake system is integrated on my 2015 CF800 (eps) version?

I have read two versions..

1) front lever is just for the fronts.  And the rear pedal actuates front/rear together.
or
2) Front lever actuates front/rear..  and the rear pedal is just for the rear only?


Also:  My front calipers are "two chamber"..  so there are two hydraulic lines and two bleeders on each side.  And there seems to be two separate "T" junctions just in front of the power steering box.   Are these "T"s totally independant?  or somehow work together.  (its hard to see up in there)

For context:   I am still having trouble getting this system to bleed properly.  and I wonder if it is just that I am operating under a false assumption as to how this system works.   I saw on anther make/model, that someone says you have to hold down the front lever to bleed the rear master.  I just don't understand how that works unless there is some sort of front/rear valving that changes how the brake fluid is routed under different braking situations.

[Grandmaster Splash]

Hi Cave Eagle,

Ok the braking system is split as follows:-

1. Foot pedal right hand side operates on all wheels, when you have fitted the new master cylinder make sure you adjust the push rod at the back of the master cyl that connects to foot pedal to get full travel of the master cyl piston. If you do not get the full travel of the piston in the master cyl you will never evacuate all the air. The height of the pedal to get the full travel is in the CFMOTO workshop manual for your machine.
2 The R/H handlebar lever operates the front brakes only.
3.The L/H handlebar lever operates the rear brakes only, "PLEASE NOTE" this is not hydraulic operation its mechanical and functions as the handbrake.

Procedure to bleed the brakes as follows:-

1. First bleed the the systems that operates all wheels, "Strongly Recommend" a pressure bleeder, you can hire one or purchase one, they can be operated by compressed air or my mains power with an inbuilt motor.  Connect the pressure bleeder to the master cylinder first behind the foot pedal, walk round each wheel an open each bleed nipple in turn until air escapes. Then with one of the front bleed nipples open press the foot pedal lightly, now close the nipple. Each pressure bleeder tool has its own bespoke set of instructions. Should you attempt a manual non pressure bleed procedure you will be very luck if you evacuate all air from the system.
2. We are now left with the R/H handlebar lever that operates the front brakes only, snag here is you will never find a screw on top with a pipe adaptor to fit the reservoir on the handle from the pressure bleeder kit. So we have to revert to manual bleeding, top up the reservoir, open the two front bleed nipples and connect a pipe to two receptacles. Now go get a cup of coffee whilst gravity does its job, keep a check on the reservoir and the two bleed receptacles. Let at least three reservoirs bleed through, just before the 3rd reaches half way, apply the lever slowly and release it. Now shut off the bleed nipples, top up the reservoir and if luck is on your side you should have evacuated all air from the system.

 Take Care......Have Fun.....Live Long...........Grandmaster, Flash & His Furious Ride

[NMKawierider]

It looks like this and the best way is to back/reverse or pressure/power bleed them. I recommend back/reverse bleeding.

[caveeagle]

Any chance you have a source for the pressure cap that fits?  I think it has an inner diameter of 48mm.  I have not found a pressure bleeder with that size cap yet.

I do have a spare cap.  so I may just drill a hole and put a barb fitting on there for a home made pressure bleeder

Hi Cave Eagle,

Ok the braking system is split as follows:-

1. Foot pedal right hand side operates on all wheels, when you have fitted the new master cylinder make sure you adjust the push rod at the back of the master cyl that connects to foot pedal to get full travel of the master cyl piston. If you do not get the full travel of the piston in the master cyl you will never evacuate all the air. The height of the pedal to get the full travel is in the CFMOTO workshop manual for your machine.
2 The R/H handlebar lever operates the front brakes only.
3.The L/H handlebar lever operates the rear brakes only, "PLEASE NOTE" this is not hydraulic operation its mechanical and functions as the handbrake.

Procedure to bleed the brakes as follows:-

1. First bleed the the systems that operates all wheels, "Strongly Recommend" a pressure bleeder, you can hire one or purchase one, they can be operated by compressed air or my mains power with an inbuilt motor.  Connect the pressure bleeder to the master cylinder first behind the foot pedal, walk round each wheel an open each bleed nipple in turn until air escapes. Then with one of the front bleed nipples open press the foot pedal lightly, now close the nipple. Each pressure bleeder tool has its own bespoke set of instructions. Should you attempt a manual non pressure bleed procedure you will be very luck if you evacuate all air from the system.
2. We are now left with the R/H handlebar lever that operates the front brakes only, snag here is you will never find a screw on top with a pipe adaptor to fit the reservoir on the handle from the pressure bleeder kit. So we have to revert to manual bleeding, top up the reservoir, open the two front bleed nipples and connect a pipe to two receptacles. Now go get a cup of coffee whilst gravity does its job, keep a check on the reservoir and the two bleed receptacles. Let at least three reservoirs bleed through, just before the 3rd reaches half way, apply the lever slowly and release it. Now shut off the bleed nipples, top up the reservoir and if luck is on your side you should have evacuated all air from the system.

 Take Care......Have Fun.....Live Long...........Grandmaster, Flash & His Furious Ride

[caveeagle]

Do you have a prefered method to pressure/reverse bleed?  I was thinking of looking for the smallest hand sprayer I could find that would allow me to attach a hose to it.  All the pressure bleeders I see for sale seem way to large for doing small jobs 2/3 times a year

It looks like this and the best way is to back/reverse or pressure/power bleed them. I recommend back/reverse bleeding.

[NMKawierider]

Do you have a prefered method to pressure/reverse bleed?  I was thinking of looking for the smallest hand sprayer I could find that would allow me to attach a hose to it.  All the pressure bleeders I see for sale seem way to large for doing small jobs 2/3 times a year

It looks like this and the best way is to back/reverse or pressure/power bleed them. I recommend back/reverse bleeding.

Really this is all you need:

https://www.amazon.com/Effortlessly-Adapters-Universal-Hydraulic-Motorcycles/dp/B0C1P2K2QW/ref=sr_1_7?crid=3Q7XAWWTSEQSA&dib=eyJ2IjoiMSJ9.xWL-LSHw5-9K9BI1D2yfqbeCljy8bV4UHWeKrEpmrgJ2SAHtiYbndLmEn5d3jOgBICdhiQana_iMuqv0QA47zxQ6M2Oq3Q_W3kt__7_O4Bbk_Rlh5WCfP0WqX4siL5cE-nS_AM44WAYrqKJGBmao__1CtVLvfT-u_HjhpUDfpl1v6qDl6-NfP1ZX5MPLBnmCUFAmcr7F_7nOu9Ur2kaKwUi2JVLEaqcXGhPFXcCYgoIp_1xyTF6ehP3aFJyvgmUzswN0jrCTrA5Snl_xE2zIyQNjblYt8UEdBuWH9IVJXCQjNUHZqO-1dHb5Phzfhq5vOnt4OIYVSx8n10Nl0zqzCQWi2FTq00LJgC2SRiOgXeCQ8agNkxDe0aHmmuWc9n6PRS0gV-rQ0gnSaxom-TKHudKL4HJnQv7H5zkLOzXqa2tToc9hsKe-8LgWbZ5MzszV.UkgRVHjPPDHFxhVOxkAg1IqFq3TnDKeos8eD_hP4jWA&dib_tag=se&keywords=Reverse+Brake+bleeder&qid=1739995073&sprefix=reverse+brake+bleeder%2Caps%2C149&sr=8-7