Topic: 1976 CB750F Restoration

[przjohn]

This Winter's restoration project will be a 1976 CB750F. I have been amassing parts for this bike the past few months and this past weekend started the teardown. This bike was purchased for $750 in New Jersey this past Summer and it is mostly there with only 13,000 miles and an engine that can be kicked through freely. The goal is a pretty close to original frame up restoration with complete engine teardown, new paint, chrome, etc. There will be a few non stock changes but for the most part the bike will remain close to stock. Time frame is to be complete by May so it can be on board for our annual trip to Deals Gap. Some before pics,

[przjohn]

First bump in the road had me scratching my head. This seat hinge bolt was bigger than the other and would keep spinning when turned. I ended up grinding it off and brazing in a new stud to be ready for powdercoat. It looked like somehow, someone had gotten a new bolt in there between the frame and the bolt mount, which would appear impossible as the space is to small to get a bolt between the frame and mount and then up through. The other stud appears to be the standard spot welded stud. The frame showed no signs of cutting or welding?

[Jerry Rxman Griffin aka MuthaF'er]

If you need any help locating parts send me a PM. I've been down your road a few times since I bought mine in 4/75 and am in the middle of a F build now.
 

[przjohn]

If you need any help locating parts send me a PM. I've been down your road a few times since I bought mine in 4/75 and am in the middle of a F build now.

Thank You, that is what I love about this forum. A good bunch of guys enjoying these old bikes, sharing tips, and helping each other out.

[madmtnmotors]

At 13,000 miles I recommend leaving the bottom end alone. The only reason I would even tear into the top end would be in the event of a stuck/seized piston, a leaking head gasket, or to install an 836 kit. Otherwise, I would just fix everything else, maybe paint the engine, and ride the crap out of it.

Member ofreen is approaching 200,000 miles on his 75 CB750F with the original engine intact.

[riffman12]

I'll be following this closely. Exact same bike I'm working on - same color too

here's my build thread: http://forums.sohc4.net/index.php/topic,152046.0.html

I'm sure we can help each other out here

[przjohn]

Back at it again after a short trip to South Carolina. After using up my entire expletive vocabulary I ended up with this, the motor out of the frame. This was my first time doing this on a SOHC 750 never mind alone, and it took a bit of learning but I got it out by having the frame on it's side and using wood blocks to keep the motor and frame aligned. You get spoiled working on 2 strokes, they pop in and out of frames so easy you don't even think about it. One thing is for certain, I will be calling in help when that motor goes back in.



Lots of stuff heading out, Chrome will be off to PA.



Powdercoat heads out Monday too. This is usually a quick turn around so I am hoping to have it back by next weekend

[przjohn]

I have already taken a sheeter on this bike before it even runs. The bike sat in the trailer for a couple of months before we needed the trailer. When I went and took it out I had a brain fart and forgot the front brake was Doo Doo Ben Gada.
 Once on the ramp the bike got away from me and I threw it to the opposite side of the ground I was heading to. It looks like the only casualty was the Right peg bracket. I bought a used one off Ebay and the difference is obvious, in both pics the one on the Right is the bent peg.

[przjohn]

Lots of stuff bagged and tagged.



New stuff waiting for assembly.

[przjohn]

I was surprised to see a new tapered steering head bearing kit installed on this bike. I may be wrong but assume the OEM were fall on the floor type. Looks like I may take the set I bought and put it on the New Spare Parts Shelf that my Wife knows nothing of. See, that's the difference between the sexes. Women have no problem returning anything that isn't even the right color. Guys, on the other hand, will return a part that is definitely wrong but think twice about something they, "Could Need Someday"



With Powdercoat and Chrome ready to go Monday paint still needs to get out as it is a long lead item. This tank has had a very nice, " JB Weld" patch job. That will need to be scrubbed off and repaired with the tank getting a Caswell Liner before it heads off to the Painter.

[SOHC4 Cafe Racer Fan]

I like how organized you are with the tear down. 

That JB weld on the tank is pretty jenky.

[ofreen]

At 13,000 miles I recommend leaving the bottom end alone. The only reason I would even tear into the top end would be in the event of a stuck/seized piston, a leaking head gasket, or to install an 836 kit. Otherwise, I would just fix everything else, maybe paint the engine, and ride the crap out of it.

Member ofreen is approaching 200,000 miles on his 75 CB750F with the original engine intact.

Not quite Wilbur, just over 153,000.  But still going strong so who knows?  I agree, with only 13,000 I'd leave it mostly alone unless there is an obvious problem.  But as we know, there is a lot of difference between an engine that has been run regularly and one that has been sitting, even if it will turn over. 

If the engine isn't otherwise opened up, I recommend retorquing the head.

[przjohn]

Finished up disassembly including the wheels and forks. This one tool has sped up a restoration for me more than anything else. I can't believe I use to take wheels apart and save the old spokes, never mind what a PITA some of those old tires are to take off. I save just a few spokes and label them as a reference. The rest, along with the wheels and tires are already in the dumpster.



Here is another great tool. After having a small Oxy Acetylene set up in my truck for 30 years, I always had access to one. Now that I am in the office that is not a job benefit anymore. In the shop I have been using a $20 Home Depot Mapp Gas torch and though it works good, it can't even come close to the Oxy Acetylene. Old bearings and seals pop out super quick with is baby, it also has many more uses, takes up little space, and is very mobile.

[przjohn]

One of the things I like about tearing down an old bike is learning about it's history, and that usually means what type of hack owned or was working on it in the past. Here is how one PO thought you could clean up old spokes by applying Silver paint on them with a brush.



Hubs are now ready to be cleaned up, have new bearings and seals installed, and be laced to new rims.



Disks are being shipped out for grinding and drilling. This is one area that will not have the stock look. I like the way the drilled disks look on The Norton and CB400F restorations and this bike will get that too.



Had just enough time to finish the fork lowers. I use to go through a whole process of sanding down to 1000 wet and then polish. Now, they get an ultra fine glass bead, Tripoli polish, and then Jewelers Rouge. The bead takes a little time as it is not very aggressive and leaves a nice smooth finish, but it is still much quicker and easier than all that sanding.

This is a good point to be in a restoration. The project turns the corner from tear down to prep and assembly. In the coming weeks, God willing and the creek don't rise, it should start turning back into a motorcycle.

[przjohn]

The main project this weekend was getting the paint ready to go out, and that meant dealing with the tank. This is by far the worst tank I have restored, it leaked like a sieve and had been JB Welded. Thankfully it had never seen a liner so that was one less thing to deal with. First step was to clean the inside of the tank. First was an Acetone rinse with a box of drywall screws, then a water rinse, next a 50/50 Muriatic Acid and Water rinse, then about 7-10 water rinses. The screws are then removed. I have learned the easiest way to get all the screws out is to use water and wash them out. If you just keep shaking the tank and try and get all the screws to fall out dry it can be frustrating. Filling the tank with water and shaking the screws out with the water is much easier and quicker. Once the tank was clean it was time to remove the JB Weld and replace it with solder.



Here is the solder being blended into the tank and the painter can take it from there.



The bottom was even worse.



The bottom didn't need much blending, just enough to not interfere with the frame.



After everything was soldered up and held water it was 4 hours on the hair dryer and then a final Acetone rinse in case any flux got into the tank.



The tank then got 2 coats of The Caswell Liner Kit. The tank will now sit for about ten days. The petcock stub will be drilled out and the petcock installed to make sure it is free and clean to install after the tank comes back from paint.

[przjohn]

The 2 trim pieces for the seat base and tail piece that have a color matching tape.



Heat gun and some Acetone made quick work of the tape. The pieces then got polished and my hope is The Painter can repaint the mid portion of the trim. To be honest after they polished up they looked like they could go back on like that, similar to a Kaw Triple seat trim.




Everything is now ready to head to paint right after the holiday. The tank door and side panels are going to be the same color as the tank and tail piece. This is one deviation from stock, I just think it looks better. The Black side panels to me just leave a big blank space in the middle of the bike, it will look better with color.

[przjohn]

The hubs got painted in VHT Universal Aluminum. They are going to a get a gloss clear on them that I think will look good and the VHT will match the engine paint. I did a KTM 495 the same way and it came out very nice.

[calj737]

Glad to see you save that tank. I think I would have cut out the rusted metal and welded new metal back in personally. Solder and Caswell will seal it, but the metal thats there is now very thin and makes me cautious about relying on it. The 2x Caswell will help add some stability to it. Just don't be amazed if your repairs don't hold for the long term.

[przjohn]

That was my concern too. I looked on Ebay for a better tank but found nothing but junk. Welding in new metal was not an option for me. After looking into the tank I feel pretty confident that the Caswell will do it's job. The base of the tank inside where the corrosion is has a very thick layer of liner down on it, 1/4" maybe. This tank will be a true test for me of the Caswell kit, I have had great luck with that product, even on fiberglass tanks.

[przjohn]

Got the powder coat back today, 19 pieces total. Just had to put the reproduction VIN Tag on, it's a nice little detail.

[Jerry Rxman Griffin aka MuthaF'er]

Isn't fresh powder great! Looks good. Where did you get the tag done?

[przjohn]

A guy on Ebay does them. He's in Sweeden, I think.

[przjohn]

After another week away it was back at it this weekend. Most everything revolved around getting ready for a rolling chassis. Forks were rebuilt with new tubes, seals, caps, dust caps, and springs. Wheels got clear coated over the VHT Universal Aluminum with new bearings and seals, Honda spokes, DID Rims, new tubes and fresh Metzlers. If I can sneak out of work a little this week, a few other items may get prepped and a rolling chassis could be on the stand after next weekend. That would great to have that, and then some, done by Christmas. The Holidays really slow things down with all the parties and such, and I ain't exactly one to shy away from the holiday spirit and Egg Nog.


Getting set to build a wheel.




Steve McQueen watches over the truing process.




Wheels and forks ready to go.




Manchester Honda got in a boat load of KTM stuff for Christmas so the Wife and I stopped by on Saturday to do some Christmas shopping. I got this apron, (pretty good deal I thought for $15 and change) and now don't know how I ever worked without one. If I had this thing years ago I might not have drawers and drawers filled with greasy dirty sweat shirts. I like the pockets too.

[SOHC4 Cafe Racer Fan]

Nice work apron, but beware.  You may get the KTM bug.  Super Duke-itis!

[przjohn]

Nice work apron, but beware.  You may get the KTM bug.  Super Duke-itis!

Too late, been a KTM rider since the early 80's and have more than a few KTM branded trinkets. Even the Dog's dish is officially licensed merchandise  . One of the bikes I have awaiting restoration is an 83 KTM 250MXC with history and a story behind it. I have been collecting parts for that bike for a few years, including an NOS tank. If everything goes smooth with this 750F that may be able to get done this Winter too.