Many people ask what is the best way to get a machine back in service that has not been in use for a long time. If you ask a career mechanic, prepare for a long answer! He'll jump to worst case and you'll end up rebuilding the whole bike! There are so many different levels of condition possible in a fifty-plus year old Honda. That said, here is how I would go about putting a CB500 or CB550 back into service. We'll assume this is a machine that is purchased as a project but is believed to not need a complete frame-off restoration.

1. Very often, the front disc brake will be stuck, making the bike hard to roll onto your lift. A hard smack with a dead-blow ("compothane" rubber, shot-filled) mallet straight onto the brake caliper 90 degrees to the wheel will usually shift the caliper's piston enough that the wheel will roll. The brake system will still need to be rebuilt, of course. Don't worry about hurting the disc. You won't. And avoid squeezing the brake lever until you do rebuild the brake. At that time switch to silicone fluid to prevent this recurring, especially if you're going to store it more than ride it.

2. The first rehabilitation step is to remove the ignition points cover and using a 23mm socket and handle determine if the crankshaft will rotate. If not, you've already exceeded the resurrection level and entered the restoration realm. You now have a big job ahead of you. And when rotating the crankshaft from here on out, you probably should remove the alternator cover and rotate the stuck or nearly stuck engine from that side to avoid damaging the ignition's lightweight 23mm hex. But I'll say I'm not much of an advocate of forcing pistons to move in rusted cylinders. I would rather disassemble the engine and repair it. But I know most people won't do that.

3. Assuming the crankshaft rotates, connect a battery in good condition to the bike and using a quality compression tester (not an inaccurate $70 cheapo), measure the compression of all four cylinders. Hold the throttle wide open. If the carbs are jammed shut, then remove them--a compression test requires maximum air entrance. If the start button is inoperable, bridge the start solenoid with a screwdriver or connect the battery direct to the starter. Don't do the compression test using the kick lever. It won't be as accurate, If the bike has a lot of cobwebs and rust showing, squirting a little WD-40 in each cylinder is a good idea to help break down any rust that might be in the cylinders. Don't use engine oil as that will artificially increase your compression readings. If the result is under 150 psi (at sea level), adjust the valves to 0.005" (0.13mm) and retest compression. If still under 150 do a leakdown test (this requires a specialized tool) on each cylinder to pinpoint the cause. The goal is 150 psi or better compression and 10 percent or less cylinder leakdown. This engine left the factory with 170 psi. Think hard about what the results will be of all your efforts on a bike that has a low-compression engine. Forums are always saying 120-130 psi is okay. Nonsense. Even in perfect trim these bikes are fairly pokey. You will be disgusted at how a 130 psi bike runs.

4. While doing the compression tests you'll have opportunity to inspect the spark plugs and the hole threads in the head. Folks seem to cross-thread these pretty easily so scope 'em out.

5. Assuming at least 150 psi, let's move on. See what shape the carburetors are in. Remove them and remove their float bowls. Look for two things: one, is anything broken inside the bowls, particularly the float pivot posts. Two, is there corrosion and if so, is it bad enough to have compromised the main jet tower. These carburetors are made of a zinc-rich alloy, making them very susceptible to corrosion. Often, a carburetor body has to be replaced because the main jet tower is eaten up badly enough that it will not reliably grip the main jet. This or a broken float post will, again, force you to evaluate your financial commitment. Just part of the process. Count your costs. Pros don't jump in with both feet and spend a ton of money on a bike whose engine, the heart of the machine, is sick. Neither should you.

6. If the carbs are rebuildable, then see if the ignition system works. Does it produce a spark? You don't even need to crank the engine to do this. Simply lay a plug and plug wire on top of the engine and with a screwdriver open and close the points (with the keyswitch and kill switch on, of course). If you get spark, then service and time the ignition. If aftermarket points are evident, replace them with original. Time the ignition statically and service the plug caps.

7. Rebuild the carburetors. Do not use kits. Get the float bowl gaskets from 4into1.com, the o-rings from newmotorcycleparts.net, and the float valves from Honda. The factory float valves are spendy, but they're the best. If you care about the bike, do it right.

8. Replace the o-rings at the intake manifolds and mount up the rebuilt carbs. Check/add engine oil to the crankcase and using a remote fuel supply see if you can start the engine. Keep a fire extinguisher handy. If it starts, you're halfway home. If not, you'll need to find out why. You already know about compression and spark, so that narrows it down for you.

9. If it won't start, spray some brake cleaner aerosol into the airbox without the air filter element, hold the throttle wide open, and keep that fire extinguisher handy. See if that makes it start. If so, the problem is likely carburetor related. These carbs rely on the idle jet to start the engine, so the idle circuit is a good place to start your troubleshooting in the case of a no-start combined with good compression and spark.

10. Unless you have already changed the engine oil, don't run the engine long. If the engine runs on all four you have at least a good starting point and can be confident that, given reasonable compression, spending money on the other things the bike needs will be worth it.

11. Now that you know the bike is worth it, spend the money. Change the oil and filter, inspect the tank for rust and if possible put in fresh gas. Change the fork oil, air up or replace the tires, service or rebuild the brakes, do needful maintenance on electrical connectors (which they definitely will need), adjust the clutch, and replace the air filter and spark plugs if necessary. Adjust and sync the carbs, lube and adjust the chain, and time the ignition dynamically (that is, with the engine running).

12. After the test ride, lift the bike back up and check for oil and fuel leaks, recheck the drive chain slack, adjust the engine idle if necessary, and after the engine cools, recheck the valve clearances, retest compression, and re-synchronize the carburetors.

13. During the second valve adjustment, connect up your leakdown tester and at each valve tap on the rocker arm while watching the tester's gauge. If the reading drops this indicates excessive carbon buildup on the valve. This is very common. If it's major, you should do a "water clean" of the engine's combustion chambers. Afterward, readjust the valves again and measure the compression again.

14. If you're really serious about fine tuning your machine, here is an outline for what I call the "super-tune". This is where the veteran mechanic applies his experience with the machine to make it function optimally.

15. There are probably going to be a lot more things to do to the machine, such as steering bearing replacement, adjusting the charging regulator, replacing the wiring harness, for example, and inevitably, correcting a number of bad things that have been done to the bike previously. That's the way of fifty year old Hondas. Enjoy.