The Honda Owners Club

Hi, Have a reasonable record with doing this, however this has has got me stumped. Replacing hose on front brake; absent mindedly operated lever when hose was disconnected and since then , diddly squat fluid output from master cyclinder. Looked up Mr Haynes and operation of lever was a no no. Any advice about whats going on here? Thanks in advance.

I'm a little bit confused at what's happened. I find the easiest way to start bleeding brakes after hose replacement is to open the the bleed nipple several turns. Fluid will gravitate out on its own after a while. Tighten the nipple up and then bleed as normal.

Hope this helps.

Regards

Chimpy

Well I have had a similar problem .... twice and with both my bikes.

The first time was with my CX500 I wanted to change the fluid and being a bit green I just pumped the system empty and on filling the reservour I couldn't get a drop of fluid to go through the system, i spoke to my neighbour who is a bit of a wizard and he said with his old Suzuki he just poured in the fluid as Chimpy said and gravity did its thing........... Not with me it didn't ......I left it all night long and not a drop went through.
So I went to the local bike shop .... 50 mile round trip (yep that local for wales) they did know my problem and have had it several times, they said I could buy a special pump which pumps the fliud in from the bleed valve upwards .... but it was expensive and only really worth it if I was to be working on bikes all the time .... an alternative was a one way valve which is put on the bleed nipple which allows air or fluid to pass one way through but not return .... so I bought it and off I went.

Back home I fitted the one way valve and tried to pump fluid through .... still nothing hmmm !!
My neighbour then said that somthing that can happen is that a large air bubble can build up in the master cylinder which can stop fluid going through one way out would be to fill a large shringe with fluid and try to pump this into the system backwards .... through the bleed nipple ... however at this time I didn't try this but what I did do was to place the palm of my hand over the reservoir and pump with my hand and after several attempts air bubbles started to rise and the more I pumped with my palm the more air rose.

It was then I was able to start slowly pumping fluid into the brake hoses stopping to fill more fluid in and sometime repeat the process eventually I enough fluid in the system to bleed and fill the system as normal.


The second time it happend to me was when my master cylinder return valve decided not to work anymore and after gettings sorted I had to refill the system I used a combination of the above and pushing fluid in backwards with a shringe and bleeding using the one way valve.

Cheers Witch.

Thanks for that Witchmaster; I'll head along a similar road and let you know how it goes

Squeeze lever gently but before/as you release it tighten the nipple so it locks the fluid down. Repeat this several times. This should clear any trapped ait in master cylinder.

Thanks for the tip Witch; syringe technique worked with little hassle; air lock vented into reservoir as expected.

Dibble wrote:Squeeze lever gently but before/as you release it tighten the nipple so it locks the fluid down. Repeat this several times. This should clear any trapped ait in master cylinder.

True Dibble that is generally right .... however if there is no fluid in the hoses .... it doesn't work I find the palm of the hand as a pump on the reservoir work fine for me.

Anyway glad one of my tips worked for you Greyhound

I have had this problem with bikes and car clutches, and it can be very frustrating. I have tried the gravity method, fast pump, slowwww pump, with the nipple open and with the nipple closed. As already mentioned the problem is an air bubble in the master cylinder, and squeezing the lever just compresses the air, my last attempt I put very little fluid in the cylinder, just enough to cover the outlet, then gently tapped (with a piece of wood) the master cylinder, the bubble appeared, a drop more fluid added, a gentle squeeze and I was then on my to bleeding.