MY 1979 CB750 DOHC BUILD

[sgtslag]

The sprocket information can be had in the FSM, which can be downloaded from the home page of this site, for free.  The OEM chain was a continuous (no link), 630 O-ring chain.  The 630 is uber-heavy-duty, and not particularly common, but it can be found.  Avoid non-O-ring chains -- too much hand's-on maintenance, not worth the price.  Spray a chain lubricant onto the new chain every 300 miles, preferably a dry lubricant, which won't attract dust.

I would strongly recommend using a full synthetic oil in the engine after you finish rebuilding it:  Honda engineers designed the 1979's engine to run at 250 F, the thermal limit of conventional oils.  A synthetic oil has a thermal limit of between 350-500 F, before it breaks down into carbon sludge.  The least expensive synthetic oil, is probably Shell Rotella T6, ~$22/gallon at Wal-Mart.  It is a diesel oil, rated SM for cars; higher in detergent than the usual automotive oils; it has a viscosity of 5W-40, so it is safe for your engine, with easier starts at 5W when it is cold.  Cheers!

[RodneyCB750K1979]

Update for February 10 2013.  Cleaned and painted the cylinder head, jugs, and engine block.  Cleaned the center and kick stands.  Looks like I may have to remove these to have painted. Will soon install pistons and assemble the jugs and cylinder head.  I have never done this before.  I read where the timing chain will need to be pulled up using a bungie cord tied to the ceiling. Do I need a piston ring compressor or can I just squeeze each ring as they enter the bore?  Sounds like I need another body to help.   Comments?

[750K8]

Powder coat it if you plan to keep it.

[RodneyCB750K1979]

Cleaning and painting complete on the engine. Some polishing of the aluminum remains.  Getting anxious to install the pistons and cylinders.  

[RodneyCB750K1979]

I need to make a decision on either cleaning and touchup paint the frame or stripping the frame and having it painted.  The engine is nearing completion.  How much time am I looking at removing the swing arm, stands, fenders, forks, wiring . . . sanding and prepping for paint . . . . . getting painted. . . . and reassembly? Wet painting versus powder coating?

[Hoosier Daddy]

RodneyCB750K1979 wrote

I need to make a decision on either cleaning and touchup paint the frame or stripping the frame and having it painted.  The engine is nearing completion.  How much time am I looking at removing the swing arm, stands, fenders, forks, wiring . . . sanding and prepping for paint . . . . . getting painted. . . . and reassembly? Wet painting versus powder coating?

Thats a tough question... anywhere from a good day to two months for prep. It depends on your work habits, condition of the parts, unforseen incidentals, and how much attention to detail you have.

[TOOLS1]

You should be able to strip it, paint it, and have it back together in 2-3 days.
TOOLS

[750K8]

If you went the Powder coating method and you had parts diagrams with some decent mechanical aptitude (which you have), you could probably do it in 2-3 weeks, only because the place that powder coats usually have some slight delay because they will be blasting + powder coating. You will also have to replace more bushings/seals if you went the powder coating method. Then again, your bike will be brand new.

It all depends on how you feel about the bike. Is it something that you dream about, and plan to keep forever? Powder coat it. There's no other option.

Is it something you want to turn around after installing the engine? Spray paint the areas that need it.

Powder coating leaves for a much more durable finish than rattle can paint. It also acts as a better sealer. It doesn't fade, and and lasts through all weather elements. It is the superior finish, by far, for frames, chain guards, wheels, battery trays, stands, and other various parts of a motorcycle. Once you get a part powder coated, you will quickly see why it's favored.

Shooting Krylon or Rustoleum has its purposes, but to me it doesn't belong on a frame. It belongs on the backside of fenders and for random touch-up purposes IMO.

I've used POR-15 on my swing arm, and I personally don't consider that the "right" thing to do in the end. I only did it because I plan on doing a frame-strip in several more years, and I wanted something to tide me over until then so I can enjoy my bike as opposed to having nothing to ride for this year. I would treat spray painting the same--you're putting material on top of something that isn't clean or treated for future-proof use.

The problem I think is that you may not know what you want out of the bike, and I don't think we can answer that for you. If you are performing a restoration, then you should powder coat it.  It will make it brand spanking new.

[Piute]

750K8 wrote

If you went the Powder coating method and you had parts diagrams with some decent mechanical aptitude (which you have), you could probably do it in 2-3 weeks, only because the place that powder coats usually have some slight delay because they will be blasting + powder coating. You will also have to replace more bushings/seals if you went the powder coating method. Then again, your bike will be brand new.

It all depends on how you feel about the bike. Is it something that you dream about, and plan to keep forever? Powder coat it. There's no other option.

Is it something you want to turn around after installing the engine? Spray paint the areas that need it.

Powder coating leaves for a much more durable finish than rattle can paint. It also acts as a better sealer. It doesn't fade, and and lasts through all weather elements. It is the superior finish, by far, for frames, chain guards, wheels, battery trays, stands, and other various parts of a motorcycle. Once you get a part powder coated, you will quickly see why it's favored.

Shooting Krylon or Rustoleum has its purposes, but to me it doesn't belong on a frame. It belongs on the backside of fenders and for random touch-up purposes IMO.

I've used POR-15 on my swing arm, and I personally don't consider that the "right" thing to do in the end. I only did it because I plan on doing a frame-strip in several more years, and I wanted something to tide me over until then so I can enjoy my bike as opposed to having nothing to ride for this year. I would treat spray painting the same--you're putting material on top of something that isn't clean or treated for future-proof use.

The problem I think is that you may not know what you want out of the bike, and I don't think we can answer that for you. If you are performing a restoration, then you should powder coat it.  It will make it brand spanking new.

                                             

[RodneyCB750K1979]

Well, today I decided to strip the frame down.  This took me less than 2 hours to accomplish.  The bike tipped over twice resulting in broken front turn signals. Lesson learned: remove front wheel/tire to keep the center of gravity low. I'm planning on cleaning the components and painting gloss black using an automotive enamel coating with hardening agent.

[shinyribs]

Looks like a good amount of progress!   Careful and dont crack them eggs

[750K8]

Bare metal surfaces need to be primed before painting, preferably with etching or epoxy primer if choosing to go with the non-powdercoat route. Spraying with automotive paint is definitely better than Krylon or Rustoleum. Just make sure ALL the rust is gone and know what you are spraying over.

Sometimes just dropping it off to a sandblasting/ powder coat surface is easier if the frame needs it.

[Piute]

750K8 wrote

Bare metal surfaces need to be primed before painting, preferably with etching or epoxy primer if choosing to go with the non-powdercoat route. Spraying with automotive paint is definitely better than Krylon or Rustoleum. Just make sure ALL the rust is gone and know what you are spraying over.

Sometimes just dropping it off to a sandblasting/ powder coat surface is easier if the frame needs it.

          I Agree But
       Automotive "etching base coat/clear coat"
       IS NOT more durable then Rust-oleum 500f Engine Enamel witch I myself us on my bike
      (tank,covers,faring)along with lots of wax ,gas spills will show but not harm paint just buff
      (rubbing compound)and keep the wax applied as much as 1's a month,
      keep looking sharp any how.

       For the frame If it's been any type of accident should be gone over real well for cracks in welds(rust will make those crack show),I was very lucky here my bike only had rust on a few welds on bottom N around swing arm(swing was bad)
       Use A Rust Treatment (follow direction for type)I went with Permatex#81775,turns blk when dry use at least 2 coats.I never went back over and top coated with paint wasn't needed couldn't tell(due to locations) Many of us have are way of doing things I like mine to last and I'M EL-CHEAP-O

     Powder-coat maybe best for most parts figure down time and cost and repreping for bolts to fit.
         

[RodneyCB750K1979]

I completed the frame disassembly and prepped the frame for painting.  I was amazed at the poor quality of welds on the frame. A lot of weld splatter and wire feed left.  I ground these off.  400-grit sanded over paint nicks and scratches. Lots of rock chips. Shot with two coats of etching primer.








This is the single stage coating I'm going to apply

[RodneyCB750K1979]

The battery tray is being disassembled and soaked in ammonia water solution to derust.

[RodneyCB750K1979]

Swing arm pivot pin and bushings

[shinyribs]

Wow! You got the swing arm bushings out in one piece! You got skills!!!   lol

[LukeM]

Very nicely done, Rodney.  This is very well documented, and should be handy when you put it all back together. It'll be a museum piece when you get it reassembled.  I'm sure you're looking forward to the moment it fires and stumbles into an idle.  No better feeling, and makes all the work worthwhile.

Keep going...you're doing great.
Luke M

[RodneyCB750K1979]

Painted the frame and components today.  Glad that is over with. Ended up shooting 1 quart.  3 applications.

[RodneyCB750K1979]

Start of engine reassembly.  I used the hose clamps for piston installed.  I aborted these as the nice bevel in the cylinder liner end worked nice to compress the rings. A small screwdriver was needed to help the rings along.  Installed the new o-rings in the jugs.  Used copper head gasket sealant. Torqued head bolt cap screws to 28 ft-lbs in 3 stages.