brake bleeding problem

[highpsi03]

Trying to bleed the front brakes on this r6 track bike im building.. (2001) When i bought the bike the brakes were squishy, so i figured they needed to be bled, so i thought i'll just replace the lines to SS while im at it. Replaced the lines, replaced all the copper washers. I've been bleeding for about 30mins with no luck. I've bled lots of brakes and clutches and never had this issue. I'm thinking the master cylinder is possibly bad? Is that common on these bikes? The method is as follows:
Dot 4 fluid full, submerge hose in fluid, pull handle in all the way, open valve, allow bubbles to come out, close valve... Pump furiously, repeat about 100x... Any ideas?
Thanks!

[TFOGGuys]

drain the system, remove the bleed screws and tape the threads with teflon tape (you'll notice the thread tolerances are crap), and then power bleed the system.

[highpsi03]

I will try that, thanks.

[highpsi03]

Same thing, at this point i believe the master is most likely bad.

[TFOGGuys]

Are you power bleeding (vacuum or pressure)? Most bike brake systems are nearly impossible to manually bleed, because the master cylinder simply can't displace enough fluid to force the air down to the calipers. I can power bleed most fronts in less than half an hour ($33) plus the cost of fluid.

[highpsi03]

I'm manually bleeding per the yamaha manual. I've done a few bikes this same way and it worked out ok. I might need to get a vacuum pump from work and try again.

[Matt]

Can you bleed from the master cylinder? My master cylinder banjo bolt has a bleeder on it. That makes bleeding dry lines easy, all the air wants to collect there.

[highpsi03]

Finally got them bled, manually, and rather easily. Cracked open the banjo on the master to let the air out and it bled within 5 minutes.

[dragos13]

Manually bleeding is the only way I bleed my R6, and my brakes are TIGHT. I have seen people with aftermarket brembos who have more squish then my stock setup.

Good work :)

[Sarge]

Manually bleeding is the only way I bleed my R6, and my brakes are TIGHT. I have seen people with aftermarket brembos who have more squish then my stock setup.

Good work :)


The Brembo's are great, but it really is an issue of bleeding and maintaining. I've got an RSV, who's back breaks are SHIT unless you bleed them regularly. My next mod is going to be replacing the rear sets and brake MC... But anyway, the way everything is set up now, you actually have to remove the rear caliper and turn it upside down to get all the air out, because the drain nipple is at the bottom.

highpsi03, make sure the breaking system doesn't have any "high" spots in it, or other places for air to get trapped. Manual can be great, but check out the forums at www.apriliaforum.com and see some of the vacuum setup guys have put together for less than $30 or so. Manual, hand pump type things that seem to do the trick. Just do a search for "bleeding brakes."

[highpsi03]

The Brembo's are great, but it really is an issue of bleeding and maintaining. I've got an RSV, who's back breaks are SHIT unless you bleed them regularly. My next mod is going to be replacing the rear sets and brake MC... But anyway, the way everything is set up now, you actually have to remove the rear caliper and turn it upside down to get all the air out, because the drain nipple is at the bottom.

highpsi03, make sure the breaking system doesn't have any "high" spots in it, or other places for air to get trapped. Manual can be great, but check out the forums at www.apriliaforum.com (http://www.apriliaforum.com) and see some of the vacuum setup guys have put together for less than $30 or so. Manual, hand pump type things that seem to do the trick. Just do a search for "bleeding brakes."
Thank you.