Complete service, repeated each year. (I serviced the 500 I had in the 70s every 60 days, but that was back when I rode 25,000 miles a year). This exercise is more important than any modification or other service. It has the most impact. Judging from my customers and the buzz on the Internet, many don't believe this. But it's true.
Made sure oil pressure switch was the later (black top, 750) type (it was). The original (orange top) ones tended to leak.
Replaced my 1973 model's larger 73-78 taillight with the more classic appearing, smaller 1971-72 taillight. It was already in one of the bins of parts. Nice.
Inspected clutch pushrod. Lack of maintenance can ruin this part and many have substituted the inferior, early, all-steel CB450 part out of frustration. Mine has escaped the drama I was happy to find.
Replaced glycol brake fluid with silicone. Used all factory parts. I have done this with a countless number of vintage Hondas, almost all of them customer's bikes. Surprisingly, this bike has the best working brake of any that I have owned. Plans for upgrading it are on hold because I can't imagine the brake being any better.
Did the o-ring mod to rocker shafts. This should be done on all of the bikes that do not have the later pinned shafts. Honda dealer mechanics were doing this back in the day and it works very well.
Adjusted voltage regulator for increased battery charge rate. Every owner of this model should do this.
Modded front brake lever to result in more precise freeplay. The rubber cushion Honda put in at the factory does not permit proper front brake setup.
Installed Shinko tires. They work well. It would never occur to me to ride my bike on the nearby mountain roads spiritedly as I do with 70s-tech, block tread and rib tread tires. No way.
Removed seat lock. Nuisance.
Replaced rear brake rod with XL250 cable. This was a common mod back in the day that I also did to my first CB500 four. It reduces the tendancy for rear wheel hop.
Installed ammeter. I have done this on my last three machines. Previously I had used various Brit meters and their Taiwanese copies, but this time I used the backlighted one found on the India-made Royal Enfield. It's a good part.
Replaced battery with Tru-Gel brand. This is an incredible battery.
Installed hazard lights system, another thing I have done on all my bikes.
Installed turnsignal beeper. The beeper came from a Honda scooter. It has a good, not annoying tone, and just the right volume. My previous bikes got this also.
Replaced front brake pads with full metallic type. This really makes a difference.
Jetted carbs down for my altitude. Couple main jet sizes is all.
Installed Dyna 2.2 ohm ignition coils and specially-made, soldered copper core wires and old school automotive type non-resistive caps.
Advanced camshaft 2 degrees.
Dropped oil pan to de-sludge and inspect engine lower end. This will be repeated periodically.
Removed clutch for inspection. Discovered it contains CB750 springs. Reassembled with no changes as it works flawlessly, better even than my previous CB500.
Lowered carb jet needles to -3.
Installed quick ("1/4 turn") throttle. This was done in two stages over a two-year period, the first time resulting in a 20 percent reduction in rotation, the second netting a 30-40 percent reduction. And without adding any parts. Plans are for another reduction but this will require some special parts.
Installed easier throttle return spring. This is a touchy thing to do because the CB500/550 carbs have a lot of friction in their linkage which for safety requires a moderate return force.
Replaced intake manifold studs with bolts. This makes getting the carbs on and off quite a bit easier. While I was doing all that jetting, this was helpful.
Replaced fork seals using factory seals.
Replaced airbox with universal type K&N cannister style air filter. This necessitated a main jet increase of five sizes. Although two online sources have emerged for the adapter plate that makes this mod possible, I wasn't aware of that at the time and I made my own. Besides, I think mine allows a larger filter, possibly the largest filter that will fit between the sidecovers. I started with one too large and had to go to a slightly smaller one that wouldn't intefere with the electrical equipment.
Installed CB650 camshaft. This was accompanied by the obligatory 650 tach drive gear, and later the 1975 CB750F tachometer was added because its gearing is supposedly closer to the 650's and its appearance (color and proportions) matches that of the 500.
Replaced stock steel wheels with (Chinese-made, kit) aluminum alternatives. Replaced wheel bearings and (hard-to-find) seals in hubs at same time. Though I have considered cast wheels, the aluminum hoops better suit my "sleeper" ethos.
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