73 Honda CB750 Custom Build Part 38 - Brake Master Cylinder

Rebuilding the master cylinder and bleeding the front brakes.
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[@rayworx]

When bleeding the brakes (an old tip from American Honda... yes I was a tech back then) Do NOT pull the brake lever all the way to the handlebar when bleeding the brake. I tie a shop rag onto the grip and place the knot between the grip and the lever. Pull the lever til it touches the knot but no farther. Keeps the seal from going farther than needed.

[@scoop-n7o]

Thank you Dino. Your CB750 videos have been extremely helpful. You are a legend.

[@faizmurtaza4841]

Thanks man After few hour struggling bleed my brake..but when saw ur video especially the bubble in master pump tips make my bleed work less then 5 min...

[@GaRbAllZ]

Great job Dino, You make it look so much easier than it really is and without cussing!

[@keepitrunning]

I tend to use a syringe to do my brakes, saves a lot of pumping. Either pump fluid up into the line like the man with the turkey baster, or draw fluid down from the master cylinder, saves a lot of work.

[@bobbyc.2873]

Here's a hack a mechanic taught me years ago. He took a large turkey baster and attached a clear tube to it just like the one you used here, sealing the connection with alternating layers of silicone and electrical tape. You use it by sucking up some fluid, then push the tube onto the bleeder and sqeeze the bulb. It forces the fluid up the line and fills the master cylinder. I've used this method on many bikes. It works well.

[@jack002tuber]

+Bobby C. They sell a commercial reverse bleeder for cars like that.

[@bobbyc.2873]

That's good to know, thanks. I'm gonna look into it!

[@wswan81]

Another trick is once bled..cable tie lever overnight, any remaining air can slowly work uts way back to the mc overnight

[@f1david]

Thanks for posting the video. Now I have my front brakes working again.

[@pawetokarski7429]

Nice to watch Your movies. I hope some day I will buy CB750 and rebould it. Best regards from Poland!

[@Johnathanqq1105]

CB750 is my dream and favorate bike !

[@ronicard]

Nice job with the video, Dean! Getting close to being a rider (a legal one!)

[@rosswarby2430]

coming along nicely well done deano

[@napolianwas]

you can seat the first seal onto the spring and then install.

[@MrFreakwent]

Have you ever tried pushing the caliper piston back while opening the bleeder before emptying the lines to get all the gunk out of the caliper ? ?

[@Stressboy1]

Dino looking forward to seeing you put on the hand grips I want to replace mine but just not sure how to do it

[@DeanSegovis]

+Stressboy1 Coming up soon!

[@daveco1270]

I'm still new to this stuff. Does the hole in the banjo bolt have to line up perfectly with the opening in that metal piece that attaches to the hydraulic line? Is there any trick to that? And what size tube should I buy to bleed the brakes?

[@spaceoner1987]

Short strokes will get the job done quick!

[@memories808]

Well done!

[@jaflolara]

Looking shiny that CB! Dino, what are the plans for the gas tank? that patina looks good

[@davidgyawn]

great video. Here is a question I've often thought of... Why are brake reservoirs of different sizes? I have a Yamaha fz1 and it has the smaller rectangle one. But is see other bikes with big round ones. Ane they are downright ugly. why the difference?

[@TaenXD]

+Karma Cozy I'm pretty sure hes keeping it original

[@frankkelly2245]

well made sir

[@Mephysto74]

You are at the restourant today? :)

[@delmascriss7299]

way good info. tell me more about jis.. screwdriver. .,.?...

[@nao_tomori]

Are you planning on repainting the tank or are you gonna keep the cool worn out patina'd look?

[@TaenXD]

+Karma Cozy +Karma Cozy I'm pretty sure hes keeping it original

[@davidbrousseau4591]

Hey Sir, Great video. I have a question on the video you did awhile ago on the zenith record player. Where did you find the cartridge needle for it? Thank you for the help. David

[@DeanSegovis]

+David Brousseau I honestly don't remember. I searched Google for vintage turntable parts and found a site that had it.

[@roymcmasters1257]

Did not see the part where you took it apart

[@007mercucio]

(1) I really wish you had included video of extracting that C clip. It's a real biatch to remove... your method would have helped a lot of people to see how. (2) There is an aftermarket check valve you can fit onto the bleeder, which makes it so you don't need to rotate the bleeder valve orientation to pump the old fluid through. (3) This video is misnamed in a way... your bike is a 73, but the master cylinder is weird AF. It is not stock for the bike. Even so, it is still a useful vid, but it was confusing to me to see the wrong part on a 73 at first, until you said why...and I had to re-listen to what you said there, to make sure of myself, at first. (4) Thanks for making this video regardless. I really appreciated it. Once I rebuilt my brakes before internet told people how, and I felt like it was almost a coin toss to figure out how to orient the master cup (or cap - whichever it is called). That was about 10 years ago. Finally after that 10 years you solved the mystery for me. I did install it correctly. :) (5) On my bike you would NOT want to hover over the reservoir with a camera, because when it is pumped even a little too fast, it backsprays brake fluid from that hole, and it can squirt into your eye. Yes, mine did that to me. The safe way to do it is to put the cap over the top so it can not spray into your eye, or onto your gas tank's paint. And you want to squeeze slowly for this part, just to reduce the spray even more, and also to prevent air bubbles from being pulled down through the air-surface of the reservoir, and down into the brake line...On the stock brake reservoir, you need to keep adding the fluid to it during the entire process, to ensure that no air gets into the line. The stock part's reservoir is much more shallow than this non-stock one you have.

[@classiccycleconnection9334]

007mercucio You can also place a good size coin in the reservoir to prevent the pressure return hole from spitting back . (like a US quarter) leaving the coin in there doesn’t hurt anything long term either .

[@randalmontgomery4595]

I spent hours with circlip pliers and ground down long nose pliers, finally took it to local custom bike shop and the owner got it out in under 5 min. using a pair of dental hooks (picks with curved end making a semi-circle)

[@apx5777]

nice job. how do you get the feel to tighten things without using a torque wrench? I never feel confident in doing it in case I strip the threads, or don't do it right enough. especially the banjo bolt.

[@DeanSegovis]

+apx5777 You just get a feel for it with experience. Using a torque wrench helps you feel how tight bolts are.

[@psygn0sis]

A lot of people are getting fed up with satellite and cable providers for their price gouging and poor customer service, and switching over to streaming services like Roku. (Like me). It's so prevalent that internet providers are being pressured into integrating monthly limit caps. Luckily, I have a fibre connection to my locally home-grown ISP that's less than a mile away, they have excellent customer service and will NEVER cap their subscribers.

[@wartoc3708]

Weird question(s): 1. Does anyone know what the approximate PSI this or similar master cylinders put out or capable of? 2. Does anyone know of a pressure transducer for a motorcycle brake system or can I use an automotive transducer with a reducer (if needed)?

[@MrRasmusolsen]

great great great.

[@LilDoggy]

Hell yeah, now I know I can do that without breaking something

[@alanwilliams3677]

Easy when you know how.Now would you bleed the brakes on a CBX 750?I've tried everything and can't manage it.Replaced pistons,seals,brake lines and mastercylinder. Blead repeatedly till no more air comes out and brake is still spongy.Must be missing something but don't know what.

[@DeanSegovis]

+Alan Williams Replace the brake hoses with braided steel lines. HUGE difference! Old rubber lines can become weak and distort under pressure.

[@alanwilliams3677]

+Dean Segovis I did,Dean - twice.Ditched the splitter because people told me it can trap air.Now have two lines going directly from m/cylinder to calipers -no better.Weirdly, with just one caliper connected I get good pressure but when I add 2nd ,pressure is lost.Local bike shop thinks replacement m/cyl is probably dodgy because it's a pattern (copy) part.It worked for 3 years,though.Shop advises m/cyl refurb kit but that will probably be a copy as well.Bikes - who needs 'em?

[@robertbrandywine]

Did you get this problem solved?

[@alanwilliams3677]

No.I gave up chasing my tail and put the bike back on the road.Probably rely on back brake a bit more.I read an original road test of the CBX 750 in SuperBike magazine(online).They liked the bike but mentioned that front brake lever came almost back to the bar.I suspect a performance m/cylinder might sort it but I'm not prepared to spend the money.

[@cbrmotardizzato]

yes but what about the tank, no rust inside? coating inside? repaint? I think the bike deserve it... ciao Dino

[@superchapin2g]

You failed to say that Lisa's background noise was caused because she was working with some metal parts, following one of Ichiban's tutorials -lol

[@risc19]

+superchapin2g BAD ASS!

[@GaRbAllZ]

+superchapin2g Look out for the NEW Ms Hack-A-Week channel

[@josephcivita1450]

I use brake fluid to lube the parts as I put them together. Also, don't use DOT 3 fluid. Its crap. I use DOT 5 in everything. If for some reason you don't like DOT 5, at least use DOT 4.

[@HackaweekTV]

Main difference between 3 & 4 is boiling point. 3 is Glycol Ether, 4 is Glycol Ether/Borate Ester. Dot 5 is silicone based and should NOT be mixed with anything glycol based. It's also hydrophobic so it doesn't absorb water.

[@josephcivita1450]

@@HackaweekTV that's correct. I use dot 5 in my bikes after total rebuild of the brake system. It's not for everyone, but I prefer it.

[@mikelast7918]

it was always my understanding that no type of oil or lubricant should ever enter the master cylinder apart from brake fluid....or have i heard wrong?

[@aramscholten6541]

There is special mounting grease included in most master cylinder repair kits, which is also sold separate as brakecylinder paste (e.g. ATE Bremszylinder-paste (thats German so it must be good)) or you can use fresh brake fluid. You're right about not just any grease should be used.

[@kevinchamberlain7928]

Brakes are overrated! Mine always seem to slow me down!

[@robertbrandywine]

The K3 is the 1972 model, not the 1973 model.

[@007mercucio]

in fact it was produced from 72 to 73...and for whatever reason, people call them a 73... better to not confuse the topic :)

[@wswan81]

Cringe everytime i see a small flat blade anywhere near rubber seals

[@drumstyx]

That doesn't look like any CB750 master cylinder I can find -- none I can find had a plastic reservior.

[@007mercucio]

same here... nor any google pics either... but in the vid he said it was from a 77... i don't know about that, but it definitely does not match mine

[@kasperkjrsgaard1447]

Propably from a 750 F2 or F3. They had double disc’s as standard.

[@timmerk]

I have two 77 CB750K stock master cylinders and the reservoir is metal and part of the master cylinder. The 77-78 master cylinders don't have a brake handle adjuster screw.

[@wombatmoto1938]

please don't paint the tank.