Saul Posted yesterday at 12:14 Share Posted yesterday at 12:14 Having trouble bleeding the front brakes on my CBF600. After I did the calipers it appeared to bleed up fine with no bubbles coming out of the calipers but the lever wasn't that hard, would creep back to the bar.  Brakes do bite but not strong enough for my liking. I initially thought it must be something I did wrong rebuilding the calipers so I cleaned up the old calipers and put them back on same result.  Still have the lever coming back to the bar. Have bled and rebled the system but no improvement.  Gave up for today but am going to have one last attempt tomorrow, starting off bleeding the master cylinder then down to the left caliper then right.   I'm a bit stumped really, never really come across this before. Thinking could be something to do with the ABS pump or perhaps the master cylinder. Happy enough to rebuild the master cylinder, to be honest I wouldn't mind deleting the ABS system but I want to get to the bottom of what is causing the problem before going to the expense of buying new brake lines although it would be an upgrade.  Link to comment Share on other sites More sharing options...
Catteeclan Posted yesterday at 12:27 Share Posted yesterday at 12:27 Assuming the hoses are still standard, clamp the hose from the master cylinder. If it's still spongy you have air in the cylinder or time for a rebuild. It can be a bitch getting all the air out. The method I used on the R6 yesterday. Calipers hanging by the pipes. I have a milk bottle with a pipe running into it connected to the open bleed nipple, one side at a time. Topping up the reservoir and allowing the fluid to run through itself. Tapping and moving the calipers around. Once you start to get clear fluid I did up the nipple and operate to level a few time to push some of the pistons out a bit. Clamp the pipe, open the nipple again and push all the pistons home with your hands. Did this a couple of time per side and got a cracking level. Another is the big syringe connected the open nipple forcing the air and fluid upwards. Cover everything around the res as you will spill some. This way also works well. Â Have fun. 1 1 Link to comment Share on other sites More sharing options...
Saul Posted yesterday at 13:01 Author Share Posted yesterday at 13:01 Cool thanks for that.  Yep the hoses are standard and original so 18 years old now, but are made of unobtainium so if they need to be replaced it will be an ABS delete as I am not that keen on buying used ones.  Given me something to work on now. I never thought to clamp the line to isolate the Master cylinder.  Link to comment Share on other sites More sharing options...
Saul Posted yesterday at 13:17 Author Share Posted yesterday at 13:17 48 minutes ago, Catteeclan said: Assuming the hoses are still standard, clamp the hose from the master cylinder. If it's still spongy you have air in the cylinder or time for a rebuild. It can be a bitch getting all the air out. The method I used on the R6 yesterday. Calipers hanging by the pipes. I have a milk bottle with a pipe running into it connected to the open bleed nipple, one side at a time. Topping up the reservoir and allowing the fluid to run through itself. Tapping and moving the calipers around. Once you start to get clear fluid I did up the nipple and operate to level a few time to push some of the pistons out a bit. Clamp the pipe, open the nipple again and push all the pistons home with your hands. Did this a couple of time per side and got a cracking level. Another is the big syringe connected the open nipple forcing the air and fluid upwards. Cover everything around the res as you will spill some. This way also works well.  Have fun. Just been out and clamped the master cylinder line, lever still came back to the bar so that's it, air or rebuild or both.  Link to comment Share on other sites More sharing options...
YamaHead Posted yesterday at 14:39 Share Posted yesterday at 14:39 If it were mine....I'd rebuild the master cylinder & install steel braided lines. Sometimes the original brake lines can develop obstructions internally, trapping air & causing havoc.... 1 1 Link to comment Share on other sites More sharing options...
Saul Posted yesterday at 15:06 Author Share Posted yesterday at 15:06 25 minutes ago, YamaHead said: If it were mine....I'd rebuild the master cylinder & install steel braided lines. Sometimes the original brake lines can develop obstructions internally, trapping air & causing havoc.... I am very tempted to do just that to be honest.  I think I will do it in stages though as I will have to bypass the ABS if I go with braided lines as far as I know.  The master cylinder rebuild kit is £30 so will do that first, if that doesn't cure it I will get some braided lines next.   1 Link to comment Share on other sites More sharing options...
Six30 Posted yesterday at 17:11 Share Posted yesterday at 17:11 if it was mine i would take it to a bike shop and let them sort the fucking brakes out 1 Link to comment Share on other sites More sharing options...
Six30 Posted yesterday at 17:15 Share Posted yesterday at 17:15 just had a thought @Saul... they recon people talk to plants and they respond...   why dont you go in your garage and try singing to the brakes.... video it and post on here. 2 Link to comment Share on other sites More sharing options...
Buckster Posted 22 hours ago Share Posted 22 hours ago You should check online to see how to open the valves on the abs pump for bleeding the system. Also are the front and rear linked at all, you may need to bleed the rear brake as well. Lastly a Mityvac is your friend. 1 Link to comment Share on other sites More sharing options...
Saul Posted 22 hours ago Author Share Posted 22 hours ago Not linked and bleeding is the same as for a non ABS bike on the CBF600. I have a speed bleeder as well as a knock off Mitvac type thing, also did it the traditional way, used all three in different attempts. It's why I think the master cylinder needs to be rebuilt.  1 Link to comment Share on other sites More sharing options...
Renegade Posted 19 hours ago Share Posted 19 hours ago 10 hours ago, Catteeclan said: Another is the big syringe connected the open nipple forcing the air and fluid upwards. Cover everything around the res as you will spill some. This way also works well. That's how I always do it. Link to comment Share on other sites More sharing options...
Catteeclan Posted 7 hours ago Share Posted 7 hours ago If you clamped the hose next to the M cylinder I assume you've got some air in/let it run out of fluid. Chances are the air is in basted banjo joint, this is where the syringe works well. 2 Link to comment Share on other sites More sharing options...
Saul Posted 1 hour ago Author Share Posted 1 hour ago Yep going to try that tomorrow, been out on my working bike all day today.  Link to comment Share on other sites More sharing options...
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