SOHC.co.uk Forums > CB500/550
CB550k1 US Import - UK registration
McCabe-Thiele (Ted):
--- Quote from: juitz on October 03, 2022, 02:03:43 PM ---I can see the m/c piston moving, and I can prime the m/c.
I can also feed fluid from the bleed nipple all the way to the m/c with a syringe.
Tired the matchbox trick as well.
I may get a single spurt of oil when I press the lever but it just feels like there's air in the system. Any resistance I can feel is from the lever return sprin and friction.
--- End quote ---
When you feed fluid with a syringe from the bleed nipple do you continue until all bubbles are gone ?
Can you pump the lever until it gives a solid feel then open the bleed nipple and close it before the lever is fully applied ?
Sometimes the air finds its way up on its own when standing overnight after an initial poor lever.
Oddjob:
Have you checked to make sure the return hole in the master cylinder isn't blocked? It's the really small hole you can see at the base of the reservoir, get a really thin piece of wire, something like one of the wires off a stiff wire brush, poke it down and check. If you're checking the MC that's where the bubbles will come from when it's working.
You could also try this if you're desperate. If you have an original hose refit it onto the MC. Clamp the hose with a pair of mole grips, does the lever go solid, it should. If not try tilting the handlebars so the banjo bolt is at the highest point, gently flick the lever just enough that it's just starting to push the piston, any air trapped will rise to the highest point and should come out of the hole listed above. Every now and then try a harder pull of the lever, don't get the lever to touch the bars EVER, or you can push fluid past the piston. If you can get the lever to lock up solid the MC is working, gently release the mole grips so they just allow fluid past, do a few pumps and then remove the MC from the bars, keep it tilted so the banjo is the highest point. Remove the old line, fit the new with new crush washers. This makes sure the fluid doesn't start to drain away from the MC and allow air in again. Get the lines connected whilst keeping the MC as low as possible and tilted up. When everything is ready try to bleed again but keep the MC low and tilted. Any air now must go up the line, do this until you get pressure then remount the MC on the bars and see how it feels. If not perfect bleed again but this time on the bars. Won't hurt to keep the banjo tilted up by moving the bars.
As the new brake caliper is the same as the OE caliper (but cheaper) I doubt it's that which is causing the problem.
juitz:
Slow progress this week as the wife and I got Covid.
But success with the front brake!!!
Finally got the brake bled - went through it step by step and finally got a nice big set of bubbles out of the master cylinder and now have a working front brake.
Once again, thankyou all for your help!
Laverdaroo:
RESULT! Niceone Dave, shit news about the lurgy though. I'm luck enough to have evaded it so far!
Dont mean to be thick but whats this matchbox trick you mention in the posts? In the past, if ever I've had an issue I always pump up the front brake and cable tie the lever into the bars and leave it over night.
Ive always had great results and a further burp is always forthcoming.
That being said, the only bike that doesnt seem to work on that I've had is Rose, my VFR8, with 11 brake lines and consider the amount of bends and bits it has to snake through means it never bleeds well and is a two man (me and the Long Haired General) and a good two hour job to get it spot on. The whole system being linked with ABS too means its a right pig. Honda have a schedule of works but if you knacker any part of this you have to start again, its that bad!
Bryanj:
Honda put out a bulletin eons ago that if you pull the lever back to bars when bleeding you can push the master cyl piston in so far fluid can leak out so people put a matchbox on the bar to stop the lever, never had it happen to me but then i usually dont bleed brakes till after switch and twistgrip fitted.
Bulletin should be in alladins cave in 750 ones
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