Restoring CB750

[Bob]

Hi
I am just about to start restoring a CB750, I think its an F2 im not sure ,
It has Comstar wheels,
twin front discs, that's all I know at the moment. Its been standing for 10
years in a garage
and I was wondering if there is anything special I should pay attention to.
It was running fine
before it was stored. The engine seems to have locked solid, but I will have
to take the head
of to repair a weeping head gasket, I will also put a new cam chain in as
ive heard they were
made of chocolate :).
Is there any thing else I should check for?

Many thanks
BoB (UK)

[Bruce Nolte]

You sure have your work cut out for you,  I wish you luck!  I would start with getting the engine running, and this should entail breaking loose the pistons in the cylinders. Since you will remove the head to repair the weeping head gasket, this will give you a chance to evaluate the rest of the motor before deciding to invest much money and time in it. The engine on my V-30 Magna had a similar scenario with its previous owner who transplanted the engine out of a wreck that had been sitting for some years and had water in the cylinders. Runs OK now, and the bike has gone through about 4,000 miles since the engine transplant. To restore the bike into reliable and safe condition will require a fair amount of work, I have broken the tasks down into different areas you will need to address.
 
Preparing to work:

Get yourself a factory service manual if you can, or at least a Clymer manual for your bike. Although optional, I would pick up a copy of " Zen and the Art of Motorcycle Maintenance" by  Robert Pirsig, and read it before starting out.  A classic book that focuses on the mental side of riding and maintaining a motorcycle, among other things,  it will put you in a good frame of mind for the tasks  ahead and the rides that will follow. Before starting assemble a reasonable collection of tools and set aside plenty of time.   Restoring a bike this old is more of a labor of love than an economic investment of time, so think of the restoration more as a learning experience than a way to cheaply get into motorcycling. The experience you gain will pay off for a lifetime, a well-maintained older bike will cause less trouble on the road over the long haul than a new bike that is abused and neglected.
 

Engine

Once the head is off, I would at the very least lap the valves with valve grinding compound. Before attempting to break the crankshaft and pistons loose, spray some penetrating lubricant such as Liquid Wrench on the cylinder walls and let it do its work. Hopefully just a little surface rust is all there is, but if there is heavy corrosion or serious water damage the engine might be a lost cause. Rusty water in the crankcase is a bad sign!  Once the engine is broken loose, flush any dissolved corrosion away with more penetrating oil,  until the engine turns freely, and clean the gasket mating surfaces before putting the heads back on. Also, carefully scrape away any carbon deposits that are on the valves, head or piston crowns, and in the intake and exhaust ports.  Use a torque wrench on the head bolts and be sure to adjust the valve clearance before buttoning it all up. It goes without saying to change the oil and filter before attempting to start it, but also I would change the oil again after a couple of hours of running time to remove any loosened rust, sludge, etc. before resuming a normal oil change interval.

Fuel System

Before putting everything back together, investigate the condition of the fuel system.  I would give the carbs a thorough cleaning and here is why:   I bet dollars to donuts that you have a tank full of very stale fuel, and that your carburetors are clogged with a gummy residue from this stale fuel. One sniff inside the tank will confirm this!  Clean the tank out by partially filling it with Lacquer Thinner, throw in a handful or two of nuts and bolts to cut the varnish coating and loose rust. Put on the cap and slosh the whole mess around for a while, let it soak and slosh it around some more. Repeat as necessary.  Once the lacquer thinner does its work, pour the whole mess out into a safe container  and dispose of properly. (be sure to retreive all the hardware inside as well)  If the inside of the tank is heavily rusted, or you have pinholes in the tank, either head for the salvage yard for another tank or use a product called Creem, carefully following the directions with it. Change all the fuel hoses before reassembling the fuel system. Stale fuel has a way of dissolving rubber and plastic hoses.

Electrical:

At the very least, you will need a new battery, even if the old one manages to hold a charge for a while. Check operation of the starter, lights, controls, etc, and make necessary repairs. Most of the controls can be taken apart and the contacts cleaned and burnished if necessary. Clean or replacc breaker points, if equipped, and replace any cracked or oil-soaked spark plug wires, as well as starting out with a fresh set of plugs. Check for cracked and broken wires and corroded connectors. I would disconnect and reconnect every connector on the bike a couple of times to insure good contact.

Brakes:

Flush all of the old brake fluid, and replace it with the proper type. Check carefully for leaks by squeezing the lever HARD. I would SERIOUSLY consider replacing the brake hose, as well as the disk caliper and master cylinder seals, even if they hold under this test. Check condition of rotors and drums, as well as linings.

Suspension: Check/lubricate/repair/replace the following as needed:

Wheel bearings
Fork Seals
Control cables/linkages
Clutch cable/hydraulic linkage
Swingarm bearing (best to check this while the bike is apart, in case replacement is needed).
Chain/ sprockets/shaft drive
Headset bearings
Tires - If they are dry rotted or worn, replace before doing any serious riding.

Anything else I missed?

Body/ Paint - At the very least, paint any rusty areas on the frame, fenders, etc. and make sure nothing is ready to fall off.  What you do over that  won't make it run better or more reliably, but the quality of the paint job is the first thing that people notice down at the local pub or wherever you want to be seen  on your Iron Horse.
Your bike will reflect your personality and the image you want to project.

Keeping Costs Down

If you have to replace more than a couple of major parts, or a host of minor stuff, you could easily spend yourself into the poorhouse getting the necessary parts new from Honda. Some stuff, like electrical specialty parts, gaskets and seals you may have no choice but to bend over for the dealer, but for a lot of the other stuff, you can often find cheaper alternatives that work just as well. Here are some:

A Parts bike:

I was lucky enough to get much of the remains of the bike that donated the engine when I got my Magna. In the year I have been riding, I have raided my old parts boxes for cables, switches, and ignition parts. Scour the junkyards and the back alleys for a
likely candidate. You can often get a complete parts bike for less than the cost of that  grossly overpriced electrical doodad you need.

The Junkyard

Find a junkyard that either specializes in cycle salvage, or one that has at least a few bikes similar to yours. A cycle recycler (bad pun intended) will probably charge more than the non-specialist, but will be more likely to have what you need.

Standard Automotive Stuff:

Hoses,  clamps, and even some electrical items are much cheaper at your local NAPA store than from your Honda dealer. Unless you are restoring it to show, why buy 6 dollar Honda hose clamps?

Mail Order Houses:

Many frequently used parts are available from aftermarket suppliers. Ask around for a particular parts supplier's reputation. Often you can get things like tires, brake linings, filters, mirrors, chains, wheel bearings, etc. at a fraction of the cost of the local dealer. Same goes for accessories.

The Internet:

USENET groups, mailing lists, online businesses, riders forums, classified advertising sites and of course E-Bay are all possibilities. Then again, you are already here on the net.:o).
 

Hopefully there are no show stoppers with the bike, but even under the best of circumstances, it will probably take several weekends and a few hundred bucks  to get her back into shape. It would be a good winter project.  If you are lucky, other than the engine work you mentioned, and some general cleanup, adjustment,  and  greaseup work, the ole inline four will rumble back to life when you hit the starter button, and life will be sweet!!  Stay close to home for a while and ride conservatively until you work the inevitable bugs  and kinks out of it.  Common  problem areas that crop up in the first few rides are oil leaks and electrical problems of various kinds. One advantage of going through the whole process is that it will give you the confidence to deal with anything mechanical your bike might throw at you, and the ability to help out when your friends have problems as well. You will become one with your motorcycle!