mattycoops43 Posted June 23, 2012 Posted June 23, 2012 Hi guys an gals.Just changed the master cylinder on my new fazer. I bled the brakes through both calipers, and got the lever to be pretty good. After leaving it for an hour or two to do other jobs, the lever went straight to the bar, so I am obviously getting air stuck in there somewhere. Is there a good way to bleed them that gets rid of this issue?I am thinking, if I let them settle overnight, would the old 'flick the brake lever' trick work, to get the air bubbles up through the master cylinder???Thanks in anticipationMatt Quote
Stu Posted June 23, 2012 Posted June 23, 2012 Sometimes you have to remove the calipers and raise them and tap them lightly to get the air too move Also it could be air at the banjo bolt on the master cylinder try pumping it up hold it back and crack the banjo open If anyone suggests holding the lever back all night ignore them its a myth air can't escape out of a sealed system! Quote
mattycoops43 Posted June 23, 2012 Author Posted June 23, 2012 Cheers, will try that. Just had a look in the haynes book (obviously didn't do that BEFORE I did the job) and it says you can remove air from the top end by removing the cap and slowly pumping the lever without undoing the bleed nipples to see if you get any tiny bubbles from the holes in the master cylinder.Holding up the calipers makes sense to me! Quote
Stu Posted June 23, 2012 Posted June 23, 2012 Yeah you can get some air out like that but not always all of it There is loads of techniques to get air out the best one I have found is filling from the bottom through the bleed nipples Quote
Colin the Bear Posted June 24, 2012 Posted June 24, 2012 If anyone suggests holding the lever back all night ignore them its a myth air can't escape out of a sealed system! It doesn't need to escape, it just needs to rise through the system and into the master cylinder reservoir.Does the lever get firm on the second pull?Air makes the lever feel spongy, no matter where it is in the system. So if it's firm, the air is gone and unless it's leaking back in which is unlikely that's not your problem. If the lever is firm after the second pull, it's not air.I had a problem with a poorly fitted pad spring pushing back the piston in the caliper. It then took two squeezes to move the slave piston far enough to take up the slack so to speakCheck you've fitted the master cylinder properly and calipers are working as they should. Quote
Stu Posted June 24, 2012 Posted June 24, 2012 If anyone suggests holding the lever back all night ignore them its a myth air can't escape out of a sealed system! It doesn't need to escape, it just needs to rise through the system and into the master cylinder reservoir. It may help it rise but that's not what you want! Because of the angles of master cylinder it will never reach the reservoir plus it it can't escape to the reservoir while the lever is pulled as pulling the lever makes it a sealed system To get the air out it needs to go down that's why you bleed them the way you do otherwise they would have invented a way to bleed them from the bottom! Quote
Guest Hodgy Posted June 24, 2012 Posted June 24, 2012 If I have completely emptied the system, to change a hose for example, I use a syringe with a short lenth of tubing to fit the bleed nipple and force the fluid in through the nipple, closing the nipple when you need to refill the syringe, so no air enters, and repeat until the fluid starts to fill the master cylinder, go have a cuppa then come back and bleed as normal in it needs it, no problems with air locks and fluid not getting through.If the problem is trapped air, then I put the empty syringe onto the bleed nipple and suck the fluid out, the trapped air will be expelled with the fluid usually.As Stu said, tieing the brake lever to the handle bar is a complete waste of time, once the lever is pulled the system is sealed so there in no where for the air to escape to.HTH Quote
mattycoops43 Posted June 24, 2012 Author Posted June 24, 2012 yes, thanks guys! I know about the lever making it a closed system, what I have heard of is just flicking the lever gently without pulling it, to make any tiny bubbles trapped right at the top come out.Anyway, I went out last night to have another look and the lever seemed firm. Not 100% sure how firm it should be as it's a new bike to me, but felt ok. This morning same again. Maybe the first time I pulled it, there was a sticky caliper or something that then moved? No idea, but it's ok now.I went to change the pads and clean the pistons, but found out why the pads came with the bike. The retaining pins are stuck in at the moment, so I haven't touched anything. Will get some WD on the ends of them, and do a few rides and then have another go. Brakes working fine, but I dont think anything has been touched for a while so it will need a good going over once the pins are free. Quote
mattycoops43 Posted June 24, 2012 Author Posted June 24, 2012 yes, thanks guys! I know about the lever making it a closed system, what I have heard of is just flicking the lever gently without pulling it, to make any tiny bubbles trapped right at the top come out.Anyway, I went out last night to have another look and the lever seemed firm. Not 100% sure how firm it should be as it's a new bike to me, but felt ok. This morning same again. Maybe the first time I pulled it, there was a sticky caliper or something that then moved? No idea, but it's ok now.I went to change the pads and clean the pistons, but found out why the pads came with the bike. The retaining pins are stuck in at the moment, so I haven't touched anything. Will get some WD on the ends of them, and do a few rides and then have another go. Brakes working fine, but I dont think anything has been touched for a while so it will need a good going over once the pins are free. Quote
polecat Posted June 24, 2012 Posted June 24, 2012 yes, thanks guys! I know about the lever making it a closed system, what I have heard of is just flicking the lever gently without pulling it, to make any tiny bubbles trapped right at the top come out.Anyway, I went out last night to have another look and the lever seemed firm. Not 100% sure how firm it should be as it's a new bike to me, but felt ok. This morning same again. Maybe the first time I pulled it, there was a sticky caliper or something that then moved? No idea, but it's ok now.I went to change the pads and clean the pistons, but found out why the pads came with the bike. The retaining pins are stuck in at the moment, so I haven't touched anything. Will get some WD on the ends of them, and do a few rides and then have another go. Brakes working fine, but I dont think anything has been touched for a while so it will need a good going over once the pins are free.I just noticed we seem to be going through the same bike list !So we both had a XJ and now fazer so what do you reckon we will have next >? Quote
mattycoops43 Posted June 24, 2012 Author Posted June 24, 2012 Lol, well, I have had a string of old jap bikes, Z, CX, GS, CB(F2) and lastly the XJ. Having had my first proper ride on the fazer today, I am blown away. Completely different to any of the older machines and vastly different! Not sure what next, but thinking I will enjoy the fazer for now. I WILL have a zxr750 one day, as it is the bike I always lusted over when I was learning in the 90s ( I know there's newer better bikes, but I don't care)Fancy a ZX9 at some point! or maybe a fazer1. Quote
polecat Posted June 25, 2012 Posted June 25, 2012 Lol, well, I have had a string of old jap bikes, Z, CX, GS, CB(F2) and lastly the XJ. Having had my first proper ride on the fazer today, I am blown away. Completely different to any of the older machines and vastly different! Not sure what next, but thinking I will enjoy the fazer for now. I WILL have a zxr750 one day, as it is the bike I always lusted over when I was learning in the 90s ( I know there's newer better bikes, but I don't care)Fancy a ZX9 at some point! or maybe a fazer1.I had a lot of jap bikes that I thought were good till I tried MY Fazer so now I am enjoying it so much I reckon on keeping it a fair while.Think if I do get a new bike it will most likely be electric by then Quote
mattycoops43 Posted June 25, 2012 Author Posted June 25, 2012 Yep. First commute today. I can see why everyone likes them. Awesome bike. Totally in love with it, from the first mile! Quote
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