I can't seem to pressurize my front brake line on my harley 1200 xl?

Question

I just changed my front brake line and can't get my front brake to pressure up. How do you get the pressure up in a brake line on a harley 1200 xlc?

Answer 1

If the bike has a few miles/years on it,,,here's ONE condition which occurs...

Brake Master Cyl Piston NORMALLY runs at only a certain depth of stroke when ya squeeze brake.
It only goes in So far,then stops against the hydraulic pressure in the normally functioning brake system.

The Master Cyl Bore is LOTS deeper/longer than That,,and Piston Travel in an Open or Un-bled system is much longer.

Crap builds up during Normal Operation over time,,Just Beyond the End of Normal Master Cyl Piston Travel.

Imagine sweeping a very dusty floor,,but only Half Way across the Room.
Nice and Clean where you normally sweep,right?

Go BEYOND that,,,and you run right into all the accumulated mess.

Same Thing happens when Bleeding a System.
Youre Over-travelling far Beyond normal stroke,,,and into the mucky gunk.

That stuff has a variety of possible effects on Master Cylinder.
*Stop Up Bleed Back/Fluid Return Holes
*Stick Piston Seals and prevent Piston from Fully retracting in the bore
*Actually Scuff the piston seal,,damage it ,in some instances

One way oth the other,,,The Master Cyl is prevented from receiving Fluid Supply to displace the air in the line.
Intake is blocked,,,so it's NOT really pumping fluid when you squeeze the brake
.....................................

Check M/C for a "squirt back" in the Reservoir when you Release the Lever.

It should also produce a Small sqirt in the Reservoir when you begin to squeeze the lever.

Push/pry Caliper Piston /Pads back IN while watching Reservoir.
You should see Fluid Returning.

Normally just cleaning M/Cyl solves it.
At 3~4 yrs old???....It May require a freshening up with new piston seals.

I know it sounds stupid that ya can "destroy M/C" which has been perfectly fine,,,merely by bleeding brakes.

But the FIRST time Ya squeeze the brake lever to Bottom against an un-filled system to begin bleeding it,,,
You're jamming the piston into an area which hasnt been Touched in Months or even Years.
Usually a "garbage dump" just a few thousandths of an inch beyond Normal Travel,,,and very often Corroded,Rough,Gritty,,etc.

Happens Very,very often....notice how often you hear about Brake Bleeding Difficulties.

Front brakes in actual Good Condition,Clean Fluid,Good M/C Seals and Bore will "bleed itself" from mere gravity.

If it wont pump fluid to pressurize the line,,,
well,,the M/C is "the pump".

And there ARE technical reasons/conditions they appear to suddenly,coincidentaly "go bad" for no apparent reason During Brake Bleeding Operations

Good Luck with it,,,it's a nuisance and can be Very frustrating.
but usually nothing serious.

Answer 2

Scoring on the piston skirt is caused by insufficient lubrication. That can be caused several things including having been too hot and excessive piston clearance. Were it me, I think I'd measure the inside diameter of the cylinder if for nothing else, peace of mind. When the front cylinder is coming up on compression, the connecting rod is going to try to **** the bottom rear of the piston against the cylinder wall. You might also look at the front top of the piston, especially the part above the top ring and see if it appears to have extra wear. Harley is known for using very tight clearances between the piston and cylinderwall, so I doubt the piston was too loose. It might not hurt to pull the rear jug and take a look at it. It would be very annoying to replace the front piston, put everything together and then find the knock was actually being caused by the rear cylinder. I don't know how large of an area is scored, but if it's not that large, the knock may be from the rear cylinder. I've pulled engines apart and was amazed at how well and quiet they ran considering what I found inside. Like the time I found large pieces of piston skirt in the oil pan and the remaining skirts fell apart on 6 of 8 pistons when removed from an industrial engine. I doubt the cylinder is badly worn, but it would still be advisable to measure it and if ok, hone the cylinder before installing a new piston. Be sure to lubricate the piston and cylinder before installing. I like to use STP for that purpose.

Answer 3

Harley Brake Lines

Answer 4

you'll need to bleed the front brake lines to remove all air from the system.. a simple process with 2 people, but can be tricky by yourself.. any air in the lines will compress when you apply the brakes. if there's any air (even a tiny amount) in the lines, your brakes will feel spongy and will be seriously unsafe. if you're unsure of how to bleed the brakes properly, get a pro to do it.

Answer 5

You may have to bleed at the brake master first and then work your way down to the brake cylinder. Small cylinders can be a nuisance to bleed. If nothing works you may have to use air pressure to do it.

Answer 6

Power/vacuum bleed the system.
Check out this link:

http://search.harborfreight.com/cpisearch/web/search.do?keyword=bleed

Skip the first item, and use any of the next 6 items to either force the fluid (and, hence, the air trapped in system) through the system either through pressure or vacuum (whichever tool you chose to use).

Answer 7

Leave the lid off the master cylinder and pump the lever until you get no air bubbles. then put the lid back on and go through the regular bleeding procedure.

Answer 8

Bill gave good advice, if that don't rectify your problem, your other option is back bleeding.

Take a one man bleeder kit and force the air through bleeder & out master.

Answer 9

You have to bleed the air out of the system.

Answer 10

Have you taken the air out of tube? Did you check the master cylinder?