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Bringing a 1978 750F back to life after 28 years in garage storage. Brake issues.

Randy L

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Hi everyone, I am a first time poster and am really glad to have found this site! I rode a lot from 75-86, but a couple of very close calls over a three week period involving 4 wheeled idiots running stoplights and just missing me convinced me to stop. Now that I have an 18 year old son who really wants to get a bike in the next year or so, I am planning on bring my old friend back to life so I can teach him how to ride safely. I have a 1978 CB750F Honda that I bought new and have had stored in my garage for the past 28 years. It was properly put into storage, i.e., I ran the engine with the fuel petcock off until it ran out of gas. I drained the float bowls of all the carbs, I removed the battery and put fresh oil in the case and tank and also a new filter and put a few tblsp. of oil in each tappet hole and cylinder. I inflated both tires and put the bike up on the center-stand and then covered it.

I am bringing the bike out of storage and have cleaned the tank of old fuel, polished everything on the bike, installed a new battery, dumped the oil from the case and tank and put fresh oil in along with a new oil filter. I will install new plugs in a day or so and be about ready for a test fire of the motor. I still have to buy and install new tires and tubes. Thus far, I am only having a couple of issues of note. When trying to pull of the right side cover it cracked in multiple places. 37 year old plastic gets really brittle so I will have to source and replace it. A more serious set of concerns are when I turn on the ignition, I get the headlight on, but the tail light is not on. It does come on when applying either brake so it does have power. I still have to check the bulb, but I think it was working when I put it into storage. I plan to take a look at the bulb tomorrow to cross that off the list. The turn signal lights work (they come on and flash). The signal beeper didn't work the first two tries, but then started to beep every time I turned the signals on fully with the switch locked on. The more serious issue is with the brakes. The front master cylinder has very little lever movement. I was trying to bleed the brakes, but I get nothing coming through the brake lines at the calipers as the lever action is very minimal. When removing the old fluid, it was obvious that it had gone way bad! It was very dark and there was a lot of gunk around the outside of the lever area and inside the reservoir itself. I removed all of the old fluid and cleaned out the gunk as best I could, but I think the master cylinder may be shot. Is is necessary to replace it or is it pretty easy to rebuild one? I want to take it off and take the line off at the T splitter and see if I can get any fluid to come out of the end of the brake line. I think the piston is likely gunked up and frozen. I would appreciate any thoughts on these issues a great deal. I have always done all my own work on this bike, having added Triple-A case savers, a Martek 440 electric ignition, K & N filter, a Luggage rack and sissy bar and a Shoei sport fairing/windscreen so I would like to continue to figure this stuff out if I can and do it all myself. Now that I am getting older though, some things are tougher for me than they used to be, but I want to keep trying!:)
 
Rebuild the master cylinder first, they're not too bad. The single circlip that holds the whole thing together can be a pain, but a little patience goes a long way. Make sure both the openings in the bottom of the reservoir are clear prior to reassembly, The fluid return opening is quite small and easy to overlook. Once the MC is done, drain the brake lines and bolt the MC back on. Remove the calipers from their brackets but leave the hoses connected. Now use your newly rebuilt MC to pump the pistons out of the calipers. If only one piston moves you might have to do one at a time (finish one, remount it, then do the other). Inspect and clean the calipers and pistons. Replace the piston seal and reassemble. New pads (yours are over 30 years old), bleed the system, and you're almost ready to ride. Now do the same thing to the rear brakes and then you'll be ready to ride! (or at least ready to stop) But only after you've replaced the tires too!
 
Joliet isn't that far from me... hour and a half or so. I come pretty close when I go up to Schaumburg to visit my son.

Sounds like you have things pretty well under control and will be on the road soon... good luck.
 
Thanks a lot for the information madmtnmotors! I am progressing, but since I am not a mechanic I am taking it a step at a time. I am pretty good mechanically and have most tools I need, but some things are probably going to be beyond my abilities. I am having some electrical issues also. I have the headlight coming on and the brake light works as well as the oil pressure light and high beam and indicator light along with all the turn signals. I don't have the neutral light, tail light, or a starter that will engage. I am suspicious of the switches. I have put new fuses in and checked as many wiring connections as I could so far, but all I get from the starter button is the temporary turning off of the headlight as expected, but no starter function at all. When I do get ready for a test fire I will have to use the kickstarter, but that is cool. Everything was working perfectly when I last rode it before putting it in the long storage mode.

I know about that circlip you mentioned. With that, I would need to buy the circlip removal pliers if I decide to attempt that rebuild. Is it really as simple as pulling out the piston/spring/cups etc., cleaning out the entire MC and then putting it back together? That doesn't sound too bad, but I am a little nervous about the calipers. If all that brake fluid in them and the lines is like what I found in the MC then I can see a mess coming. I have always done a lot of my own work on my cars etc., but brakes have always been something I have avoided I guess. At least on the bike everything is out in the open.

I am grateful for the advice and thank you very much for the reply!
 
I spent a couple of hours knucklebusting by putting new tires/tubes on both ends. I had done it before so I knew it would be a bear, but soapy water does wonders on helping to tease the bead over the rim with a couple of irons. The best part is that I did solve a couple of other issues along the way. When I was putting the rear tire back on I found that the wheel would not move as if the bike was in gear. I'm not sure how that happened, but it was in gear so I clicked it down into first and nudged it back into neutral and the wheel would turn fine again. I thought I would just check the neutral light and when I switched on the power, EUREKA! Not only was the neutral light working again, but the starter works again now too. If I remember corrrectly, the bike is designed so that the starter won't engage while in gear so maybe getting it to register in neutral freed the starter to work. I just gave it a quick blip on the switch to see that it worked. I pulled off the front master cylinder and once I removed the brake line the piston moves freely when squeezing the lever. I still plan to rebuild it either way and will order the rebuild parts tomorrow. I can see the calipers needing a rebuild also, but I am a lot closer to firing it up than yesterday.
 
I did rebuild the front master cylinder this weekend and I plan to drain the lines next and go from there on the brake systems. So far so good and taking it a step at a time.
 
Brakes

Did you verify both of the small holes in the bottom of the master cylinder reservoir were free and clear?

Yes, I did do that Madmtnmotors. The return hole is ridiculously small as you know, but I used a fine pin and could see the hole before I reassembled it.
 
Update

Yes, I did do that Madmtnmotors. The return hole is ridiculously small as you know, but I used a fine pin and could see the hole before I reassembled it.

I have reassembled and refilled the reservoir and pumped up presssure, but it is as if the pressure is built up in the master cylinder itself as no fluid comes out of the brake line or bleed screw. I have to suspect that the line or T-distribution part may be gunked up. In any case, I will troubleshoot for a while longer, but the brakes are the one issue that may require me to visit the Honda dealership to make sure it is done right. I can't live with brakes that "might" work alright. They are the one thing I won't compromise on in the interest of safety so if professional help is required I will get it done.

On a brighter note, I put a gallon of fresh fuel in the tank and tried to fire it up on Memorial Day after pumping up the oil pressure using the kick-starter. I could tell I wasn't getting any spark after removing the #4 plug and after checking around I found a loose ignition connection to one of the coils. I plugged it in and that baby fired right off with minimal cranking of the starter. There was a little smoke and some rust particles that blew out of the muffler, and the engine was running pretty lumpy at first, but it began to smooth out after 5 minutes or so. To make a long story short, It wouldn't go below 14 or 15 hundred rpm's without dying, but it did start right back up using the choke. After 10 minutes of running it died again and I couldn't get it to refire. I tried 3 more times later that day to get it going again, but no luck. I am pretty sure it was flooded so I waited until the next day and tonight I don't think the starter ran more than a half-second before it was running. I ran it a good 10-12 minutes and it is really starting to smooth out and respond more immediately to quick cracks of the throttle. I put a little octane booster in the tank and an ounce of Sea-Foam additive to help clean out anything in the carbs and I could tell it was working with the engine smoothing out more and more and also running down to about 1200 rpm's without dying. It still won't idle without a little help with the throttle, but I am pretty confident it will continue to improve with each run. One more step along the journey and so far it has been a great project to get the old girl closer to hitting the road.
 
Yeah, I gotcha. I kept touching the outer edge of the cooling fins and they were not terribly hot when I shut it down. I mostly ran it in the 1500 to 3500 rpm range with only a few runs up to 5000. I was getting a little smoke from the header collectors and engine block as it heated up after a few minutes of running, but I can pretty much tell it was some old grime, a little spilled oil and cleaning stuff that I had used. I see that as being normal as I cannot find a single leak anywhere. Once it all burns off I expect the light smoking to stop. There is still a little light smoking coming out the exhaust, but the Sea Foam tends to do that. I'm pretty sure that will stop soon enough also and it is not much anyway.
 
Thanks a lot for the heads up dirtdigger. If I am going to run it again more than 5 minutes or so I will get a fan on it.
 
New issue

Thanks a lot for the heads up dirtdigger. If I am going to run it again more than 5 minutes or so I will get a fan on it.

OK, I am really pulling my hair out now. I went out to start the bike up and just run it 3 or 4 minutes to continue to try to get it used to running and hopefully keep improving the fsmoothness after circulating the fluids and fuel/cleaner through the carbs and I have no power whatsoever when turning on the key. This is the first time this has ever happened so I am really bummed about the whole thing and just throwing up my hands. I am not too electrically inclined, but I was able to hook up my voltmeter and the batter is showing about 12.9 volts. I checked power to the starter solenoid and it shows about 14 (seems a little odd, but OK), and I also have similar power readings to the fuse block at all three locations. I replaced the main fuse anyway just to check and still dead as a doornail at the instruments and lights when I turn on the key. What could have possibly happened just from sitting 2 days after running it? I am at my wits end now.
 
Easy now! What you describe is often related to the ignition switch itself. Try wiggling the key back and forth, and maybe reach up underneath and wiggle the connector at the base of the switch and report back.
 
You are the man!

Easy now! What you describe is often related to the ignition switch itself. Try wiggling the key back and forth, and maybe reach up underneath and wiggle the connector at the base of the switch and report back.

madmtnmotors, you are the man! I had tried jiggling the key before, but I was more vigorous with it after your advice. It took about 30 jiggles, but Eureka, the lights did come on briefly. I tried it some more and got them to go on and off as I jiggled the key in the switch so it would seem that the ignition switch itself needs to be replaced. That might be a blessing in disguise in a way since I only have one key for the bike and it is next to impossible to source a blank to have cut as a duplicate. At least with a new ignition, I would get two keys and could have more made. I will still have to take the bike in to have the brakes serviced, but this is a load off my mind. Thank you so much for your good expert advice. I really appreciate your quick responses.
 
I was hoping that would prove to be the case. :cool:

Remember, although the lock for the fuel door is just a pseudo lock (i.e. anything shaped like a key will open it), the seat latch DOES require the ignition key to open it. The good news is, you can disassemble the seat lock, remove the little brass "keys" and their springs, put it back together and it will then work just like the fuel door in that you can open it with just about anything that will fit. Then you don't have to worry about two different keys. :wink2:
 
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