Topic: CB750 F1 Restoration Project - not for the faint hearted

[Don R]

  Either way I'm a big fan of oiling the motor through the oil galley plug on the right side. I've used a rubber hose, I've used an oil gauge fitting and a few pipe plugs to make a pipe nipple riser to pour oil in to gravity feed it but my best idea was using an oil tank for adding oil to car A/C systems. It pressurized the engine enough to turn off the oil pressure light for a minute or so. I did that twice. That can fill the sump so don't get carried away and over fill the motor.

[Hon3ybadger]

Take a look at my thread "1976 cb750 F1 brought back from the grave" in the projects forum. I'm doing the final touches on my build as we speak.

As far as yours goes its in ok shape. If I were you I would concentrate on replacing all the rubber bits and lubricating fluids.

 Brakes- Rebuild both calipers and contact Slingshot Cycles for some new lines. Rebuild the masters and turn the rotors for new pads. Don't go cheap here!
 Frame- Check the side stand mount to frame for cracks. Mine was almost completely falling off. I'd consider Tapered head bearing from All Balls. Address any rust and\or cracks accordingly.
 Carbs- You have that figured out.
 Hubs- All new bearings and seals from All Balls.
 Forks- Replace fork oil and seals if needed.
 Tank- I did "The Works" followed by vinegar. Took all my rust away.
 Engine- While you have the pan off replace the o-rings in the oil pump. Maybe consider a gasket kit and new hardware to replace the painted screws. Find new hardware at 4into1.com
 Tins- There is a guy on here from spokane who does world class paint and bodywork. I'd say let him paint your baby yellow.
 And please refrain from any random steampunk urges you may get. haha
 Cheers, Hon3y

[eddiebpool]

Hi Hon3y

The more I am looking at the bike the more I agree that it is in OK shape.  Crappy paint and grime is being removed to show a bike that is fundamentally undamaged and complete - ready for work.  I hooked the bike up to an old scooter battery and found all the electrics work (I even pressed the starter for a fraction of a second - I couldn't help myself).  The big job, other than getting the bike running, will be the brakes.  The brakes have not done well with time and will need a complete overhaul.  Master cylinder rebuilds front and back, caliper rebuilds, and I may replaced every component in between.  There is a short brake pipe on the front that might be OK but I think I should just replace this along with the hoses.  The front is a bit weepy and sorry, the rear is completely jammed up.  I will strip them down today and see what the state of play is.  srust58 gave me some excellent advice on how to tack the rear caliper.

Changing all the rubber stuff is excellent advice, I am on it.  This is my first weekend so will be a tear down to see what I have, and start putting together a shopping list.  Happy to hear any suggestions about what should be on that list! 

[eddiebpool]

I have a couple of queries that hopefully someone can help with.  I posted a picture of a very unusual "Peter Furlong" chain guard.  This appears to have really done its job.  I have removed it and the chain underneath looks like new - no rust spots and the only issue is the  lubricant has gone slightly sticky.  The rear sprocket looks good too.  I haven't seen the front Sprocket yet.  My instinct is to simply soak the chain in an oil and gas mix to clean it up, dry it out, then lube again.  I know there are some that would simply replace everything.  Any thoughts?

I'm tempted to put the Peter Furlong chain guard back on.  It is not pretty but clearly very effective.  Now that I have it off it looks like a moulded plastic reinforced with glassfibre.  It is very light.  A very well made piece of kit.

The braking system is off the bike.  Carbs are coming off today and I have a 4-pack of carb cleaner waiting. 

I'm thinking about a test fire next weekend.  I'm going to put a bit of sea foam down the plug holes today and leave it there until I'm ready to fire.  I was also going to get some lube directly into the top end.  Any recommendations on what?  Sea foam, WD40, just plain engine oil, something completely different?

[calj737]

Your approach to the chain and sprockets seems advisable. If you're happy with the chain guard, install it. If not, install a factory model.

SeaFoam in the cylinders is a good idea, even Marvel Mystery Oil. Top end, straight pure oil or Marvel. When you do to cranking the engine, leave the plugs out and disconnected leads. You want to fully circulate oil and lubricate any sticky bits internally. A few short bursts on the electric starter. 5 or so 2 second bursts. Monitor oil pressure. If everything appears good, install plugs and leads and fire it up.

[BeSeeingYou]

As long as the chain is not stretched out to the end of the adjustment marks and the sprockets are not hooked I think you are in good shape to run that chain.  I would think that chain guard really helps with chain life.  So much of the wear coming from road grit in the chain acting like an abrasive.  Maybe it doesn't look real sporting but it sure takes care of one maintenance issue and keeps the rear wheel clean.  I am still running the OEM chain on my bike with 11,000 miles on it.  Still looks good.

[eddiebpool]

Took all the brakes off the bike and the big issue is the rear master cylinder.  It is well and truly locked up.  Anyone any experience of getting this apart?  I have soaked in in WD40 and am leaving it overnight - not sure if this is the best idea but I couldn't think of anything else.  Any help much appreciated.

[BeSeeingYou]

  Mine was stuck too.  I assume you have taken out the C clip and pushrod and it looks like the first photo.  What you see up in the bore is the socket on the piston that the pushrod fits against(ball and socket).  This is not a sealed fit but this is where it is stuck.  That is where you want the penetrating fluid to seep in.  You can see the piston in the second photo...the socket for the pushrod is facing up.  The third photo shows the proper orientation of the internal parts.  I let mine soak and then I heated the whole thing up with a hot air gun.  Nothing happened so I stuck a screwdriver in and pushed in the piston to compress the spring. It took a bit of force...it didn't go in easy, probably no more than 1/2 inch. (I think I remember giving the screwdriver a sharp tap with a hammer)  Nothing happened.  It was late so I figured  I would try again in the morning and as I set it down on the workbench it all popped apart.
  A few other things to know are the hex nut below the cup is an access port for you to clean the fluid passages into the bore.  The return hole is very small...some use a E guitar string or something small diameter like that.  You can see the two holes looking into the cup but they take a  90 degree turn into the bore so you can't clean them from the cup.
  I have thought of other methods but not sure what would work.  I don't think you can hook up a master cylinder to pump it out as you have no way to bleed it.  Depending on where the fluid passages are in relation to the piston seals it might just flow into the reservoir cup.   Some people use grease guns to pump out pistons from calipers but you would need to make some type of adapter to fit the banjo fitting.  Possible if all else fails.
  The other thing I was going to try if mine had not come apart was to drill a hole into the piston socket and thread in a self tapping screw so I could use that to pull it out.  Just start with my first suggestion with heat and pushing in the piston a bit.  Make every effort to salvage it as they are not easy to come by.  There is an alternate master cylinder that will work if this one is trashed but lets leave that discussion for later if needed.

[eddiebpool]

That is exactly where mine is at, though yours looks a bit cleaner.  I have left it soaking with a puddle of WD40 on top and will do as you suggested.  I like the mix of science and brute force - always a winner for me! 

I have ordered some Marvel Mystery Oil - seems like useful stuff.  It is not readily available retail in the UK though I have found some on eBay and the order is in.  Any attempt to fire up the bike this weekend might be a bit too soon.  I want to take my time and be very careful.  Plenty of other things to be getting on with though.

Very small update on the crappy paint on the engine.  I tried a bit of paint stripper and the crappy thick stuff at the bottom is slowing coming off to reveal (similar to the top) nicely polished goodness underneath.  I don't know if the paint was a deliberate act to preserve the shiny bits while the bike was asleep, but I'll take it as a good result.

I am going to replaced all the cables.  There is a split in the tacho and I might as well do the throttle cables too while I am doing it.

[eddiebpool]

Quick query for anyone that has done this - I have bits and pieces on the bike that has chipped / scratched paint - small parts that appear to be powder coated.  Is there a paint that someone can recommend that will match the finish?  I can rub down and spray as I go, but I want it to tie in nicely with what is there already.  I might go for the blast and powder coat on larger parts like swing arm / stands etc but little bits I would like to take care of myself.

[eddiebpool]

Success!  Sort of.

After soaking the Master Cylinder in a puddle of WD40 for few days I put a 3/8 socket extension bar in the hole and hit it with a hammer.  It moved.  That was progress because it was well jammed.  After a few more taps it started to be movable under hand pressure and 10mins of pumping it eventually eased out, and was free. 

Scraping out all the rusty crap, I noticed once the piston was out that I had scratched up the inside - an almost prefect ring about 1inch in.  Have I trashed my cylinder?  It was such a schoolboy error, using a sharp screwdriver.  I am suitably ashamed. 

The Front Master Cylinder was moving so I'm not so concerned about that one.  I didn't have circlip pliers long enough so they are on order, hopefully arrive before the weekend because the rebuild kit has already arrived.

My Marvel Mystery Oil arrived and the bike will get the full treatment.  The carbs come off at the weekend and the journey to "test fire" begins.

[edwardmorris]

The circlip can be wrestled out using awls and picks carefully without damaging anything or buying a specialty tool for ONE application. Read through the FAQs section, lots of good tips documented there.

EDIT: Read through the Brake FAQ AND the Brakes Section under Proven Tip and Tricks.

[Hon3ybadger]

I had that scratch problem too. Measure your master cylinder I.D. to make sure its still serviceable. Chances are it is.

I took some 1500 grit sand paper, wrapped it around a 11mm (I think) deep socket. Put the socket on a locking extension add some wd40 and gently sand the cylinder bore. Kinda like honing the block but much smaller. haha Move up to 2000 grit if you want to. It took all the scratches out and only added a thousandth of an inch to the I.D. (still within spec though.) I polished my piston for no logical reason other than it was shiny! Its been two months and not a drip or loss of pressure. Locks up the rear within an inch of movement on the pedal.

[edwardmorris]

I had that scratch problem too. Measure your master cylinder I.D. to make sure its still serviceable. Chances are it is.

I took some 1500 grit sand paper, wrapped it around a 11mm (I think) deep socket. Put the socket on a locking extension add some wd40 and gently sand the cylinder bore. Kinda like honing the block but much smaller. haha Move up to 2000 grit if you want to. It took all the scratches out and only added a thousandth of an inch to the I.D. (still within spec though.) I polished my piston for no logical reason other than it was shiny! Its been two months and not a drip or loss of pressure. Locks up the rear within an inch of movement on the pedal.

Same principle for what I did with mine, but I found that a medium tip sharpie has the perfect OD for gently honing it. I used 2000 grit paper. Wetting with denatured alcohol will help if there is dried up brake fluid crud in the cylinder. (Pix show two diff MCs, but I cleaned them both the same way, just don't have a complete set of pix for either

[eddiebpool]

Electrolysis - or reverse electrolysis as is it should be known.  I'm sure there are many folks on here that have used it on a regular basis and on many parts.  I'm doing my tank at the moment after limited success with vinegar, I decided to try something new.

For those that haven't tried electrolysis - all you need is an old car battery charger, something steel / iron that will be sacrificed, and some soda crystals (washing soda).  Find a plastic watertight container (storage box, plastic bucket, etc) add however much water you feel necessary, mix in 1 good tablespoon per gallon of water, and then you are ready.  Electrolysis is typically used to add a plating material on to a base material - gold plating for example.  In this case I am removing an unwanted plating material - rust - and take it back to the base metal.

The negative connector on the battery charger should be connected to the thing you want to make rust free - in my case my tank.  The positive connector should be connected to the sacrificial piece of metal - in my case a couple of pieces of square iron bar.  IMPORTANT - Never allow the sacrificial piece to touch the thing you want to make good, you will short the system.  MORE IMPORTANT - do not allow the positive connector to go in the water - it will be eaten!  REALLY SERIOUS IMPORTANT - never use stainless steel as your sacrificial piece, stainless steel contains Chromium which is very bad for you and very bad for the environment.  Any old crappy mild steel is perfect.

I wanted to get right into the tank and found that a 25mm plastic conduit pipe fitted nicely.  I drilled out a few dozen holes and did a small plastic weld with a soldering iron at the bottom to ensure the bars didn't fall out the bottom (when you have had as many broken scooters as I have you get adept at plastic welding) and hooked it all up.  It seems to be working a treat.  As you will see from the pics, my negative terminal is under the water and this is okay.  I used my jump leads as an extension because they have more bite.  The positive is attached to my sacrificial iron square bars - outside the water of course.

If this works well it might be useful to someone else.  The people on the site have been of great help to me, so hopefully I can put something back.  I will post more pics once I get some crud out and let you know if I make any tweaks to the design. 

[Jerilee]

I've used the same process before too, not for a tank (yet) but we did all the tin for two VW motors, it works great! I may do some CB parts with the process too. I recommend it!

[eddiebpool]

Small update on the electrolysis - I noticed that the two rods didn't have much room in the tube so I took one of the out.  That seemed to speed things up.  The water is looking wonderfully horrible!  I will leave it overnight and hopefully have some photos of crud to show.  So far, so good.

[eddiebpool]

I like a good "before and after" picture.  The process is obviously working.  I'm not sure if you can see how filthy the water is.  The really encouraging thing is there are flakes of rust all over the tank and at the bottom of the plastic tub.  I'm not sure how long you should keep this process going.  I will keep going as long as it keeps working, then I will start it fresh again!

[eddiebpool]

Something unrelated that distracted me from the bike today (it is a public holiday in the UK).  In the first picture you will see to the far right part of the rear breaking system.  I'm not sure what it is called though it acts as the pivot point between the brake pedal and the master cylinder.  The was jammed tight.  I tried my big pliers and even hitting it with my lump hammer.  Nothing.  I decided it was time for me to invest in a vice.  I finally have a big boy project so treated myself to an old school big boy vice.  I don't know if Record Vices made it to the USA, but they are very well known here.  Older ones like this (pre-Irwin and actually "Made in England", not China) have a cult following.  I got this ugly duckling for the modest sum of £25, about $40.  I have given it a going over with a wire brush, removed the jaws and cleaned them up, and a bit of wet and dry and it came up looking pretty good.  I will do a proper job when I get the chance - strip and de-grease, then paint and grease up for a long and useful life.

And I got the pivot unstuck with my new/old vice!    I put the small end in the vice and battered the longer part until it surrendered.

[eddiebpool]

The electrolysis was a huge success.  Look at the water / soda mix after another night in the tub - wonderfully disgusting!  The rust inside that remained has turned black and the bits I could reach just rubbed off with my finger.  I filled it with nuts and bolt and shook the shoogle out of it.  Quick rinse and back in the tank again with fresh water and see how it turns out this time.  I have a couple of rusty things in a queue if the tank proves to be cured.  Some pics - 1) my plastic invention and the 10x10mm iron bar I used, 2) filthy water / soda mix, and 3) the process started anew.

This really works, I recommend it.    One tip I can give is to make sure you take out the tube and rod regularly to clear it.  The tube can get full of gunk and the rod gets covered too.  You can leave it overnight but the process slows down to a crawl by the time you check it in the morning.  Give the tube a shake in the water to clear it out, rub the bar down with a heavy sandpaper, then back in the tank.  I found doing this every 3-4hrs kept the system working at optimum.

I'm not so sure what to do when I'm finished.  My thoughts are to dry the tank out then give a good dose of WD40 to stop any flash rusting.  I'm taking the tank to get the paint blasted off and the chap says to empty the tank of fuel.  WD40 is a flammable solvent so not sure that will be okay.  I'm still making it up as I go along so happy to hear any suggestions. 

[martin99]

I'm going to have to try that electrolysis lark next time I get a rusty tank, thanks for posting.

Are you sure you want to get your tank blasted? I used to get a lot of these done, and no matter how well I masked them they always seemed to get some blasting media in them which eventually found it's way to the carbs. Used a lot of inline filters in those days.

[Jerilee]

I recommend a phosphoric acid solution of some kind, something like OSPHO works great
http://www.amazon.com/OSPHOG-OSPHO-METAL-TREATMENT-GALLON/dp/B000C02B3W/ref=sr_1_1/186-0234470-1315833?ie=UTF8&qid=1401230584&sr=8-1&keywords=ospho+rust+remover

When I finished wire wheeling my rear swing arm I sprayed a little on with a small misting bottle and used an old sponge to spread it evenly over the metal. Like the electro the rusty bits will turn to black and the rest will be coated and dry in under 24 hours. Non flammable and handle-able after that, clean off with acetone to paint. : )

[eddiebpool]

I can get Phosphoric Acid in strengths varying from 30% to over 80%.  A quick once over with that before painting will work, thanks for the tip.

I am inclined to take my chances with the tank stripping as long as I can get some assurances that the materials will not end up inside.  You are right, that would cause more problems than it solves.  It is laziness more than anything.  I can get the tank stripped professionally for £35 (about $50) which sounds better than spending hours trying to do it myself and making a mess.

Another night in the tub for the tank and it should be finished.  There is still crud coming out though much less than before.  I can't stress how happy I am with this process - it really works!

[eddiebpool]

Quick query about the rear brake calipers - does anyone know how to get the brake pad pins out?  There seems to be a couple of slots on the other side though I have not tried dig into them and find out if it leads to the other end of the pins.  If it did it would be an easy matter of knocking them out.  I have tried WD40 and 've got good pliers with sharp teeth but nothing is making these move. 

Any help would be much appreciated.

[Jerilee]

This may help a little http://images.cmsnl.com/img/partslists/honda-cb750f1-super-sport-1976-england-rear-master-cylinder-rear-brake-caliper-pedal_bigma000086f09_1f21.gif

I just took apart some Honda calipers from a few years later, they are a little different but the pins are very similar, they let the pads 'float'. On my calipers they had gotten very cozy in there and I needed a hammer and punch to get them out. Once out far enough I had luck with a few by getting a good grip with some vice grips and pull/twisting them the rest of the way.