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Ok so like I stated in my first topic I have just started rebuilding my first CB750. This bike has been sitting for a little over two years. Last night we started tearing things down and cleaning things up. Well after a couple of hours we got the cluster to light up and the starter was trying to engage! I will admit I became very excited at this point. We then started spraying down the chain with lube to free it up but then we realized that the rear tire is completely locked up. Nothing we tried would free it up, any ideas?
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 BRAKES I removed (caliper) mine till I was done moving/pushing it around lot easyer on this ole man
1977 CB750 F2 Super Sport
<LET THOSE WHO RIDE DECIDE><RIDE TO LIVE-LIVE FOR JESUS>
Native American from central Cal, Kickstand UP in S.W.Missouri,
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Administrator
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Is this an F or a K? If it is an F, remove the caliper and it should turn. If it is a K, there is a stay rod on the right side of the swingarm. Unbolt that from the brake hub and see if turns.
If you still have no motion, then remove the chain. If still no motion, then the bearings are likely frozen. If it does turn, make sure the bike is out of gear, reattach the chain and try to put the bike in 5th and push it around.
We are trying to find where it is frozen here and resolve that. It is usually the brakes though.
The ride IS the adventure. The destination is just to get gas!
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It's actually the CB750 C if that makes any difference.
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Administrator
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The C has the same break as the K, so just follow Re-run's advice.
TOOLS
Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run
"Fear nothing, attack everything" Eric Berry
" Oh, you read that on the internet? Clearly it IS a massive problem. Of course it CAN’t be normal operation."
1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)
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hi i am new here aswell as new to restoration projects, i have been working on a 81 cb 750 f ss, for about two years now. i am now at the point where i beleave i can ride it to the local shop to get the carbs synched.....
i hate to jack his thread but my rear tire is doing the same, when i bleed the brakes the pistions and pads stay out, i am thinking i may have a loose clamp on the lines from resevere to the master cyclinder,
sytoms are i have no brake pedal, i pump and pump the brakes the pedal gets hard i bleed them and start over, however i have gone thru 2dot bottles of brake fluid, never had bleed brakes before i kept thinking i was missing something?
on the rear caliper i loosed the the allen tool nut and there was very little fluid in it.....ithis a caliper issuse or am i right in beleaving it is in the line
thank you all in advance,
junkr honda lover since my first A.C.E 750
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I did the same (happened to me),I then was told(Paul my mechanic)To use the syringe(automotive type) Seems some use an oilpump can,But the syringe keeps constant force can be used tu suck or blow. SO I used it to take all out of res. then filled with rubbing alcahaul and push (blow)from caliper to res.gunk nasty dirty ,and i just flushed fluid thru it.Repeated this till perfectly clean,pushed some dot4 thru a few times,ffresh dot4 filled res and used Syringe to suck it thru to caliper,There was no air (ok maybe .00009 )there's always a chance.bled as reg.should STILL would bearly bleed but was clear of air.They still seemed to me to drag ,But disc never got hot or did not fill any drag while riding.
1977 CB750 F2 Super Sport
<LET THOSE WHO RIDE DECIDE><RIDE TO LIVE-LIVE FOR JESUS>
Native American from central Cal, Kickstand UP in S.W.Missouri,
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thank you i will try this, what is the purpose of the syringe?
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If you notice how used can't be done without it.
1977 CB750 F2 Super Sport
<LET THOSE WHO RIDE DECIDE><RIDE TO LIVE-LIVE FOR JESUS>
Native American from central Cal, Kickstand UP in S.W.Missouri,
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Administrator
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A speedbleeder tip works good too. You screw that in place of the old bleed screw. Open it about 1/4 turn or so and hook a hose to it. Pump your brake pedal then. The speed bleeder allows you to just keep pumping without having to close it until you are done.
Otherwise you pump hold lever and close bleed. Release, then I apply slight pressure, open bleed and finish pushing pedal slowly, hold and close. repeat. It works for me all the time.
Did you clean your caliper at all including the groove the o0ring sits in?
The ride IS the adventure. The destination is just to get gas!
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Administrator
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newtothis wrote
thank you i will try this, what is the purpose of the syringe?
The idea is to fill the syringe with brake fluid,connect it with a hose to the bleed screw(open) and inject the fluid in that way. The idea is it will push all the air up and out of the master cylinder reservoir. Once the master cylinder is full,tighten the bleed screw and you're done.
It how I do mine. ReRun's method works fine,too.
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good news the rear brake is no longer locked up... how ever i have no brake pedal at all....is it wise to try and clean the caliper or just get a new one..... how can i be sure i am even bleeding it correctly, i beleave that if there is air in the line then the pedal would be hard to push, not soft as air and making to inpact on mooving....
once we get it moving saftley i will post a youtube video so every one can see what they all helped me with thank you....
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Administrator
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You can take the caliper apart to clean it. Majority of the time when you do this it will wreck the seals and they will have to be replaced.If you think it does need to be tore down to be cleaned go ahead and get a rebuild kit ready.
Air in the line will feel soft. Air compresses and is why it feels soft compared to brake fluid,which will not compress. If you still have a soft/spongy lever try bleeding it some more. Piute's syringe method is my favorite way to do this because once you see fluid in the reservoir than you know for sure all the air is out. No way it can stay in. If you are bleeding it by pumping the lever,that will work,too.But you may have to spend some time with it.Air is sneaky and can really be tough to bleed out by the lever sometimes.But it is doable
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a couple years later I finaly understand, what the Syringe is for thank you all very much.
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Administrator
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hondacb750f wrote
a couple years later I finaly understand, what the Syringe is for thank you all very much.
 Better late than never! I'm glad Tools taught me that trick. It's a life saver.
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