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Front break problems help please

The fluid is new dot 5 which is purple so when the mc is full cant see the bottom of the reservoir - I've bled the system from the top to the bleeder and from the bleeder back to the top via a syringe and plastic hose plus have tied the lever to the bars and left that way over time. Still with everything new and bled if you pump the lever quickly it will build pressure and the brake will grab and slow the bike however when the lever is released you have to start all over again - quickly pumping the lever to build pressure.

It was originally a single disc and has the 9/16 MC
 
Apparently my memory regarding master cylinder bore sizes was not correct.

I know DOT 5 is purple, and is a little harder to see through, but you should still be able to make out which hole the bubbles are coming from. However, I don't think that is relevant to the problem you are having. The symptoms you describe are indicative of air in the system. A technique that I have used successfully to deal with the issue is: 1) squeeze and hold the lever. 2) open bleeder screw. 3) close bleeder screw. 4) release lever. 5) repeat steps 1-4 until a couple of reservoirs worth of fluid are pumped through the system. It is very slow and tedious, and the air that is pushed out isn't always noticeable, but this has usually worked for me.
 
Have you tried just gravity bleeding system while making sure that master does not run dry.

I have also read that Dot 4 and Dot 5 does not mix well and can cause a negative effect. So it is recommended to completely flush out system and just used Dot 4....

What is the recommended fluid stated on master cover.
 
Pump it up good and tie the lever to the hand grip over night, then bleed it in the morning
If that does not work your master is bypassing internally and needs to be replaced
 
2003sporty you stated "It was originally a single disc and has the 9/16 MC". Did you convert it to a Dual Disc system? If you did then you need an 11/16 MC.
tourbox
 
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