One of my favorite tasks as a lifelong Honda mechanic is a service I call a "super tune". It consists of all the things that through long experience I have found a particular model needs at any given time. This is not a simple "tuneup", a phrase that is obsolete in the industry anyway and wholly insufficient for what I am talking about. Nor would the 1980s term "tune and service"--which used to mean eassentially a factory-scheduled axle-to-axle maintenance service--be accurate. Little of a super tune involves things outside of the engine and its support systems, though I always create an observations document for the customer in which I list observed issues, and frequently a few of these things--drive chain service for example--must be addressed during the super tune. Brake system overhaul and the inevitable electrical repairs are also often needed, even on so-called "restored" bikes, but these are left up to the customer to decide. Following is a brief outline of what I do in a CB500/550 super tune.

1. First I visually inspect the machine, and I continue to do so as I work. A half century of familiarity with Honda's CB500 has enabled me to visually make conclusions about the kind of care and attention the bike on my lift has received in the past, and this directs my thinking on the systems I'll be optimizing as I proceed.

2. A compression test is an important first diagnostic step. There is no point in investing time and money in a machine that has a seriously worn engine. Virtually all CB500/550s are signicantly down on compression due mostly to valve recession. I won't proceed on an engine that has low compression. There's no point. So naturally this needs to be determined right away.

3. If the engine has over a certain amount of compression, the carburetors are removed for rebuilding. A significant part of a CB500 super tune takes place in the carburetors. They are invariably seriously neglected, suffer from rough handling, usually exhibit at least slight corrosion, and show signs of inexpert prior service (such as the use of rebuild kit parts), so they are always included. I don't even consider not rebuilding them. That's not an option. The carb work is critical, and expensive. The factory Honda float valves alone cost more than $300 (still available but getting scarce).

4. I look closely to spot the signs of a head gasket leak. Such oil leaks are very common on Honda's SOHC fours, but they pose no obstacle to a super tune. Forums are very misleading on this subject. It is very easy to prevent head gasket leaks, and it has nothing to do with any of the things mentioned on forums. Oil often shows at the decorative cam end covers too, and these too are easy to fix.

5. With a flashlight I inspect the inside of the fuel tank and check the flowability and general condition of the petcock. Very frequently the tank needs rust removal. I always drain the fuel tank because the gas in it is unreliable. Always.

6. Then I adjust the valve clearances. Two things make this special. One, I use a 0.005" clearance spec. I've done this for nearly as long as there have been Honda SOHC fours. The engine starts better, idles better, and has better throttle response at this spec. The second special thing is I adjust the valves in the engine's firing order. It makes a difference. Every experienced career mechanic knows the advantage this offers. I install new factory valve inspection cap o-rings because this prevents the caps' seizing. I see a lot of broken caps.

7. About this time I get a good look at the battery. More often than not it is a $40 battery, not one of the better brands. Sometimes the terminals are so corroded I have to cut them off. The main fuse is often corroded also, and the wiring before and after the fuse noticeably melted, and of course the stator connector also. Electrical repairs such as this that affect engine running are part of a super tune.

8. Next is ignition timing. Between this and the the carb work, these are the two most important and most labor-intensive parts of the super tune. Timing the CB500/550 ignition is an art. It takes a lot of knowledge and a lot of time. There are many steps a career mechanic takes in servicing the SOHC four ignition that the average person isn't even aware of. If a Dyna ignition is fitted, I time that, though I recommend against aftermarket ignitions and have become familiar with virtually all of them over the decades. They work when they work, but they are not as user-friendly or as long-term reliable. Nor do they deliver any advantage in either engine performance or ignition system maintenance. No aspect of tuning a CB500 is as impactive as ignition timing. Few want to believe this, but it is true. I have a how-to booklet on servicing and adjusting this ignition. Check it out.

9. The spark plugs and plug caps are next. I prefer NGK plugs, the A series, and recommend against iridium as unnecessary. I gap them a bit over the Honda spec. Virtually every SOHC four I see has bad caps. They are always loose on their wires--indicating a lack of maintenance--and they are almost always degraded from their original 5K ohms to 10K or more. I nip the plug wires and install new caps. The original NGK caps are getting rare and quite expensive. Beware of the Chinese copies.

10. The ignition coils and their primary wiring is inspected, of course. Almost always the coils need to be replaced. I use the Dyna 2.2 ohm gray coils, finding them a good replacement for the original. If there are resistive spark plug wires on the bike I change them out for actual metal wires. This is another thing that is not negotiable. I refuse to leave resistive plug wires. There are three reasons. One, non-metal plug wires reduce ignition performance. Two, that performance degrades further over time. And three and most important, such wires can never be made to connect electrically as securely as metal wires. Suppressive plug wires do not belong on your Honda.

11. The carburetors are completely disassembled down to unracked, individual bare bodies (castings). CB500/550 castings often suffer from corrosion. If slight, I file down the main jet towers. If worse, the carbs cannot be rebuilt and must be replaced. They often have been molested with rebuild kits, so all of that is put back to stock. Invariably, at least half of the threads on the carb bodies have to be repaired using steel thread inserts, due to these carbs weak zinc based alloy. The float levels are adjusted using the factory tool and method, the correct--and hard to find--o-rings go onto the main jets, the carbs are bench-synced and leak tested, and the pilot screws are set. Then the carbs are reinstalled. They go onto the engine easily, though the manifolds and airbox ducts sometimes need replacement. I fit inline fuel filters in most cases as well.

12. When the engine is started a careful check for oil leaks is made. Once warmed up, the carburetors are painstakingly synchronized to a standard that is three times as precise as the factory specification. An exhaust gas analyzer is used to confirm the pilot screw setting. SOHC fours also often have exhaust leaks, so this is listened for.

13. Finally, I adjust the clutch, which does not mean at the lever. Correct clutch adjustment requires a bit more work and some special tools. I usually also tighten the steering bearings--they are always loose. And I like to check charging and if necessary adjust the regulator. Tire pressures are checked. I don't charge any more for these things. They take only a few minutes. And every bike needs them.

14. As of June 2025, a 1970s CB500 or CB550 four super tune service costs $3000+. When brakes and electrical are added the ticket can reach &4000+. When an engine top end rebuild is added the total is of course a lot more. I have done super tunes on 70s Hondas since the very beginning, and I also do them on other Hondas such as the CB350/400F, GL1000, 1980s DOHC fours, and the CBX1000.