Author Topic: 1978 CB750F Brake Problems (Read 9550 times)

LiquidYogi · « **on:** July 20, 2012, 01:12:48 PM »

Hi this is going to be very nooby so please bare with me.

I just recently went on craigslist and bought a 1978 CB750F, my first motorcycle. I bought it because I remember riding my dads old 1980s 650 on the front and loving Honda bikes ever since so I wanted one of my own. Sadly the guy I bought it from was in the middle of turing it into a cafe racer, and not in a good way either. He still had the seat but all of the bolts were missing, I downloaded all the manuals I could find but I'm having trouble locating the correct size bolts I need to put the seat and the small storage unt, and the tail light fixture all back on together.

I was hoping someone could help me, either point me in the direction of a whole new seat and bolt set I can buy, or just the information for what bolts I need to put the damn thing together again. Thank you in advance.

Tugboat · « **Reply #1 on:** July 20, 2012, 01:31:30 PM »

http://www.xtremeusa.com/fiche_select2.asp?category=Motorcycles&make=Honda&year=1978&fveh=123330

flybox1 · « **Reply #2 on:** July 20, 2012, 01:36:27 PM »

welcome to the forum LY!
bunch of us from the PNW here

the fiche Tugboat posted lists all the hardware. there are no 'kits' of screws for seats that i am aware of.

LiquidYogi · « **Reply #3 on:** July 21, 2012, 12:43:21 AM »

Thanks guys, yeah I'm thinking I'll just have to take it to a shop knowledgable about older Hondas and tell them to figure it out. Or get an aftermarket seat and try to just attach that instead. Any idea of good aftermarket seats that will come with a kit that will fit itself instead of using the old bolts or anything? Just a thought, thanks for the help.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #4 on:** July 21, 2012, 08:40:18 AM »

Pull up one of the online microfiches, get the part numbers and quantities then order from your Honda shop using the info you found. It's mostly all available. Just did a full restore and I replaced all my fasteners. If you use BikeBandit.com just order from them since they do not provide actual Honda part numbers. Motogrid.com or ServiceHonda.com are 2 others I use.

Corbin is making a sweet seat for use now but you'll still need our hardware.

LiquidYogi · « **Reply #5 on:** July 21, 2012, 01:26:27 PM »

Quote from: Jerry Rxman Griffin on July 21, 2012, 08:40:18 AM

Pull up one of the online microfiches, get the part numbers and quantities then order from your Honda shop using the info you found. It's mostly all available. Just did a full restore and I replaced all my fasteners. If you use BikeBandit.com just order from them since they do not provide actual Honda part numbers. Motogrid.com or ServiceHonda.com are 2 others I use.

Corbin is making a sweet seat for use now but you'll still need our hardware.

Ok thanks, I was thinking of getting a new seat hoping that will be more comfortable on long rides. I'll check out the Corbin seat and see if it's something I wanna spend my money on because there is a tear in this seat that needs to be taped.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #6 on:** July 22, 2012, 07:31:38 PM »

The Corbin is the ONLY new seat available. I haven't ridden on mine yet. Restore not quite done yet.

LiquidYogi · « **Reply #7 on:** August 23, 2012, 06:49:28 PM »

Thanks for all the help guys. I'm looking at the Corbin seat and I think it's perfect but right now I still have to get the seat cowling and metal bars and all kinds of stuff actually ONTO the bike. I ordered all the bolts and nuts...and I got a lot of nuts, not many bolts. I'm trying to figure it all out but I have another question.

Will Hondamans book help me to figure out how to put the whole seat back together and onto the bike? Does it have good descriptions and photos of that because I'm looking at about 1000 pages of manuals and they don't have jack basically. Thanks again for the help.

toytuff · « **Reply #8 on:** August 23, 2012, 06:53:36 PM »

Welcome!

It's pretty straight forward. No worries.

I have a 1977 F seat somewhere but none of the hardware except the moulding.

tt

LiquidYogi · « **Reply #9 on:** August 23, 2012, 07:50:13 PM »

Quote from: toytuff on August 23, 2012, 06:53:36 PM

Welcome!

It's pretty straight forward. No worries.

I have a 1977 F seat somewhere but none of the hardware except the moulding.

tt

I'm glad that it's straightforward, but is it covered much in Hondamans book? I ask because I just ordered it because I am firmly entrenching myself in the CB750 life. As I've spent hundreds of dollars and man hours preparing...and none riding.

toytuff · « **Reply #10 on:** August 23, 2012, 09:00:13 PM »

Get use to spending and not riding.

Part of the Honda scene. I worked for five (5) months, some waiting for parts, and didn't even know if the motor was any good.

Turned out it was and it brings a smile to my face everytime I look at it.

Don't lose focus and read here. You will learn more than you ever thought you would.

Patience is a virtue.

tt

Tugboat · « **Reply #11 on:** August 24, 2012, 08:29:20 AM »

To answer your other question, Hondaman's book won't cover seat repair or replacement, but covers just about everything else and, in my opinion, is invaluable if you own a SOHC 750. Welcome and good luck!

LiquidYogi · « **Reply #12 on:** August 25, 2012, 01:11:25 AM »

Ok another Nooby question. I need some work down to fix an oil leak and maybe get some tuning done and the air filter replaced. Is there anyone from Seattle who can point me to a good shop? I found a shop with a guy who did work specifically on 70's Hondas...I say did because I asked him and he said he doesn't do work on them anymore but still owns the shop, go figure. Any help would be greatly appreciated.

bruzer59 · « **Reply #13 on:** August 25, 2012, 09:13:48 AM »

LiquidYogi

IT IS IN YOUR BEST INTEREST NOT TO HAVE UNKNOWN PERSONS WORK ON YOUR BIKE UNTILL YOU HAVE BECOME FAMILIARIZED WITH ALL OF ITS MECHANICAL WORKINGS ....

HOW WOULD YOU KNOW IF YOU WHERE NOT GETTING A SQUARE DEAL ??
THE MORE INFORMATION THAT YOU HAVE AND UNDERSTAND ABOUT THIS MOTORCYCLE WILL BE AN ASSET FOR YOU IN THE LONG RUN... READ AS MUCH INFO THAT YOU CAN.. ASK AS MANY PEOPLE ON THIS BOARD QUESTIONS ,, IN MOST CASES SOME OR ALL OF US HAVE BEEN IN YOUR PLACE AT ONE TIME OR ANOTHER... GOOD LUCK BRUZER

Jerry Rxman Griffin aka MuthaF'er · « **Reply #14 on:** August 25, 2012, 11:37:52 AM »

Yogi,

Use Motogrid.com and other online parts fiches when you can't find a "repair" in a manual. Something like the seat is straightforward and all you need is a parts diagram. Not all parts are available new anymore just because you find them on one of these parts diagrams.

Oil leak - Most all of our bikes leak to a certain degree. Repair just depends on what it is and that degree.

Air filter - C'mon dude. You just don't have someone replace a filter. You are that someone.

TwoTired · « **Reply #15 on:** August 25, 2012, 11:44:00 AM »

I've been pretty intimate with both the Stock F model seat and the Corbin.

Perhaps if you show a picture of the parts you have, and what seem to be blocking your progress, I can identify what is specifically needed to restore.

LiquidYogi · « **Reply #16 on:** August 30, 2012, 05:14:39 PM »

Thanks for the help guys...I just put the seat on and it fits fine. I put on the Tail light but it seems to have an extra wire and I'm trying to figure out the wiring for the tail lights. So I'll have to look that stuff up, should be easy enough...hopefully.

The front indicators are a bit of a pill because whoever messed with the bike took off the brackets. So I have the idea from Tweakin to put the indicators on the headlamp. There's some sort of threads there but much to small. Any ideas? I'm sure there's a bracket or a screw somewhere that'll work. Thanks again, this is actually a lot of fun and I can't wait to ride it.

LiquidYogi · « **Reply #17 on:** September 04, 2012, 02:31:55 PM »

I actually got to ride it today. Went around for a bit, noticed that the rear brake wasn't working like at all. Get to a light push down on it a little to hard and locked up the rear brake completely. Anyone know a good shop that can fix this I keep calling around Seattle and people are either too busy or don't want to touch such an old bike.

Or do you think it's a simple fix and I should just buy a kit like the one in the link and do it myself?

http://www.vintagecb750.com/products/2/chassis-brakes/42/brake-caliper-rebuild-kits-brake-caliper-piston

BeSeeingYou · « **Reply #18 on:** September 04, 2012, 09:33:01 PM »

Do it yourself....it's not that hard. You should get the master cylinder rebuild kit too. The F rear MC's are much easier to get apart than the front MC's. The problem can be caused by a few things...could be bad caliper seal or gunk locking the caliper piston up. Could also be blocked return hole in the MC or a stuck MC piston so you can see the reason for doing both. Even if it's locked up you should still be able to get the caliper off...leave it hooked up to the MC and once you get it off the disc you can use the MC to push the caliper piston out. Pump it slow and easy so you don't blow fluid all over.

SohRon · « **Reply #19 on:** September 04, 2012, 10:20:02 PM »

Quote

Anyone know a good shop that can fix this

Welcome to the club.

Part of the attraction of these old bikes is that they're simple enough that nearly anyone can work on one and be successful at bringing it back to life. The shops don't want to mess with them, so prepare to get your fingernails dirty. Buy rather than download a manual for your bike; get some simple tools; constantly refer to this site; and have at it.

Good luck!

LiquidYogi · « **Reply #20 on:** September 05, 2012, 12:01:57 AM »

Quote from: srust58 on September 04, 2012, 09:33:01 PM

Do it yourself....it's not that hard. You should get the master cylinder rebuild kit too. The F rear MC's are much easier to get apart than the front MC's. The problem can be caused by a few things...could be bad caliper seal or gunk locking the caliper piston up. Could also be blocked return hole in the MC or a stuck MC piston so you can see the reason for doing both. Even if it's locked up you should still be able to get the caliper off...leave it hooked up to the MC and once you get it off the disc you can use the MC to push the caliper piston out. Pump it slow and easy so you don't blow fluid all over.

After looking all over for shops I realized you guys are right...I'm on my own. That's fine though with this site and the books I have I can handle just about anything. The only problem is parts, looks like the places I've been looking for full kits are sold out. If anyone has a site that could have what I'm looking for please pass on the information. Other than that I might be just busting it open and replacing parts as I see what I'm dealing with. Hopefully they exist...somewhere. Thanks for any help you guys can provide me

madmtnmotors · « **Reply #21 on:** September 05, 2012, 04:08:14 AM »

Service Honda has been able to provide pretty much everything I've needed so far in my restoration of a 78' CB750F, including MC and caliper parts. I would recommend the genuine Honda packing kit for the rear master cylinder. I used an aftermarket kit and the circlip that holds everything together did not have the correct bevel shape to it and had to use the original circlip. Just an example of how some aftermarket components fall short, fortunately the old circlip was in good shape. I would consider aftermarket caliper pistons (if required) to help keep within budget, especially due to the lack of complexity for that particular part. Repairing these yourself can be quite rewarding, hang in there!

BeSeeingYou · « **Reply #22 on:** September 05, 2012, 05:03:38 PM »

I would second what madmtnmotors says about OEM. It may cost a bit more but too often the aftermarket MC kits don't quite fit as they seem designed to fit more than one bike or year. I get my parts from these guys part #13 for around $43.

http://www.babbittsonline.com/honda-motorcycle-parts?aribrand=HOM#/Honda/CB750F_A_%2878%29_MOTORCYCLE%2c_JPN%2c_VIN%23_CB750F-2200001/REAR_MASTER_CYLINDER/CB750F-78-JPN-A/2Y134102F13410210A

madmtnmotors · « **Reply #23 on:** September 05, 2012, 05:13:38 PM »

WHATEVER you do, DON'T do something like this:

Yep, some goober PO used an SAE bolt for the rear brake pedal. Fortunately the bolt threads were softer than the cast iron threads in the brake pedal so no real damage done. Chased the threads with the correct tap just to be sure... WHEW!

LiquidYogi · « **Reply #24 on:** September 07, 2012, 10:46:28 AM »

So here is the rear brake once I finally got it off. I think it looks just fine, almost new

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Author Topic: 1978 CB750F Brake Problems (Read 9550 times)