There is a thing I call a "super tune". It consists of all the things that through long experience I have found are needed to get the bike back to the factory-intended state of running excellence after nearly fifty years of inadequate and inexpert maintenance. Little of this service is concerned with things outside of the engine and its support systems, though I always create an observations document for the customer in which I list issues which are not part of the super tune. This includes such things as brake system overhaul, the inevitable electrical repairs, and suspension issues. They're almost always needed, though not included in the super tune. I have been doing this for several years now. Even if your bike was "restored", it will need most or all of these things. A lifetime with these machines proves this. Following is an outline of what the small Honda four super tune consists of.

1. I begin by visually inspecting the machine, and I continue to do as as I perform various repairs and adjustments. Almost a half-century of familiarity with Honda's CB350/400 and CB500/550 fours has enabled me to visually make conclusions about the kind of care and attention the bike on my lift has received up to the present, and this directs my thinking on the systems I'll be optimizing as I proceed. Honda's small fours are unfortunately not considered very valuable and thus tend to be very neglected maintenance-wise. If not turned into bobbers or cafes, they are often grunge-cycles. Sad to see it, but there it is.

2. A compression test is the first wrenching step. There is no point in investing time and money in a machine that has a seriously worn engine. Honda roadbikes of the 1970s are especially prone to having low cylinder compression due to the soft valves Honda put in them. This seriously impairs compression by just 15,000 miles. Though the small fours left the factory with 170 psi, they typically exhibit much less, due to this valve problem. The forums are of course silent on this issue. I won't do a super tune on an engine that has low compression. So this needs to be determined right away.

3. The compression is usually appreciably low, so then I perform cylinder leakdown tests to pinpoint where the most wears is. The leakdown tests are not needed if compression is adequate.

4. If compression is at or above a certain minimum after the above steps, the carburetors are removed for rebuilding. The CB350/400 and CB500/550 carbs are virtually identical structurally. The carburetors are completely disassembled down to unracked, individual bare bodies (castings). After an ultrasonic bath, the carbs' circuits are individually hand-vetted. They are lovingly assembled and set up, and $300 factory float valves are fitted. The small four carbs are excellent carbs. Easy to clean and service, and easy and responsive to adjust and tune.

5. Then I adjust the valves. I use a 0.005" (0.12mm) clearance. This boosts the compression. The engine starts better, idles better, and has better throttle response. I also adjust the valves in the engine's firing order. It makes a difference. Every experienced career mechanic knows the advantage this offers. I replace the o-rings on the valve inspection covers.

6. The ignition coils are inspected. The small four coils, being part of a Kettering system, frequently overheat and need replacing. The plug wires never go bad, but if suppressive wires have been fitted, I change them out for actual metal wires. This is another thing that is not an option. Such wires can never be made to connect electrically as securely as metal wires. More often than not, due to the age of the stock coils, I fit either GL1000 coils--which was a common high performance tactic back in the day--or Dyna 2.2 ohm gray coils, which are the modern equivalent.

7. The ignition points are the biggest sticking point of the small Honda fours. Improper aftermarket parts and/or inexpert adjustment make this engine very unhappy. Consider the ignition the heart of this engine. It must be right or nothing else will be. This is much more important than the carburetors. Skillful tuning is done on the points using only factory parts.

8. The spark plug caps are next. 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. The spark plugs may or not be replaced depending on their condition. Vintage NGK plugs are also getting hard to find now.

9. When the engine is started a careful check for fuel and 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 and if indicated, the pilot screws are adjusted to a reading of 3.0 percent CO. The cam chain is adjusted at this time on the CB500/550, with the engine running. The CB350/400 cam chain is adjusted during the valve adjustment, statically, because it should never be done on a running engine.

10. The CB350/400 and CB500/550 super tune, which includes the carb rebuild, costs $2500. In many cases, due to wear and neglect, a top end rebuild should be done at the same time. A top end rebuild, which includes the super tune, will run $6000 as of this writing. Brake repair and electrical work of course adds to that, and even when the customer doesn't choose them, they are always needed. For example, how many SOHC fours have squeaky front brakes? Nearly all? This is not only essy to fix, it's preventable as well. The rear brake torque arm is almost always bolted up incorrectly, and often the shoes have been dangerously recammed.

11. As part of the super tune I adjust the steering bearings--they're always loose--and test the battery charging system. The clutch is frequently improperly adjusted on the small fours also. I am not talking about the lever clearance. That is not adjustment. Correct clutch adjustment is done at the pressure plate. I lube the clutch cable at the same time. I also inspect the fuel tank and tank petcock, service the drive chain, inspect and air the tires, note any issues with the suspension, and complete my observations sheet.