TOPIC:

If you still have the oem brake hoses then it may be the extra travel is the hoses you might need to replace them because they bulge under pressure

Motorcycles are such a bitch to bleed brakes on since the amount of brake fluid that travels in a stroke is so small. The air bubbles just won't keep moving in the direction of the bleeder valves. Some guys have gone to some very unusual extremes to encourage the air bubbles to travel towards the bleeder screws including but not limited to standing the bike up such that the bleeder screws are higher in elevation than the master cylinder because the air wants to travel upwards.

If you look at the bleeder screws you'll notice that they kind of look like greease fittings and there's a reason for that. In the automotive world and quite possibly the motorcycle world on the assembly line after all of the brake components are installed, the guys on the line hook up the brake fluid filling hoses to the bleeder screws and back feed the brake fluid from the slave cylinders to the master cylinder. The brake fluid travels upwards pushing the air out in front of the brake fluid. One big air bubble moving upwards.

In a lot of automotive repair shops they have a brake bleeding chamber. Kinda looks like a round sphere which they fill with new brake fluid and then pressurize with air (maybe 20 lbs). The hose on the chamber is terminated with a cap that screws on in place of the master cylinder cap and then a valve on the hose is opened up. When the mechanic goes to bleed the brakes, all he has to do is open the bleeder valve and watch/wait for all of the air bubbles to escape then close the valve. The air in the bleeding chamber is pushing the new brake fluid in one big push and the air bubbles just can't stop and reverse flow back and up to the master cylinder.

So that's the theory. Now that you know this what can you do to better bleed brakes? I don't have access to a bleeding chamber anymore and if I did that's what I'd use. So I have come up with a cheap method to achieve a system similar to what they do on the assembly line. Get a piece of tygon hose or fuel hose that fits tight over the brake bleeder screws and a 4-8 ounce squeeze bottle with a nipple on the end of the bottle that will fit on the other end of the hose. Fill the bottle with brake fluid. place the end of the hose on the bleeder screw. Open the bleeder screw and then squeeze the bottle pushing brake fluid backwards through the system towards the master cylinder. ( I'll have to note here that you're filling the brake master cylinder so you need to make sure there's room in the master cylinder to accept the brake fluid.) At any point now you can close the bleeder screw. If the system has fresh brake fluid in it, and the master cylinder is getting too full, you can take the filling hose off of the bleeding screw and suck the excess brake fluid out of the master cylinder using the filling bottle and then go to the next bleeder screw and bleed that side of the brake system. So in effect you're constantly moving brake fluid in the direction of the master cylinder which is the highest point in the system and that's where the air bubbles are trying to hang around.

Here's a link to a video on using a brake bleeding chamber type tool
www.ecstuning.com/b-motive-parts/univers...pb-0101/Video247-HD/

Here's a link to back bleeding using a large syringe and hose.


Hope this helps.

KB

Hey Kawboy. Thanks for the reverse bleeding tip. Actually, you reminded me that I have such a tool lurking somewhere in the shop. I made it by adding a battery vent hose to an old-fashioned pump oil can and used it to bleed car brakes. I never thought of using it on a bike, assuming that the shorter lines would be less of a problem. Wrong! I'll give it a shot tomorrow.
Thanks,
Dogfight

Hey Stocktoy. Yeah, I checked out the lines under pressure and they bulge alright. Is this just crappy OEM stuff or do they deteriorate with age? (I can relate.) If you have any good sources for these lines that don't require a second mortgage, I'd appreciate it.

Thanks,
Dogfight.

its common to replace the flex lines however as to where to get them I can only suggest you measure the length and banjo fitting ID and then check amazon or another online supplier unless one of the other members knows offhand of a supplier already and get the stainless steel ones. On my 84 Toyota SR5 when I lifted it I used new brake lines off a Ford ranger they were long enough with the lift.

If the extra wire was a ground wire it would be black/yellow. Have you looked at the stator to see where it is connected? I have never come across this.