Some interesting facts, advice, opinions and observations about the iconic and very enjoyable (and my favorite) Honda, the CB500 (and CB550). In no particular order. Go here for my likes and dislikes about the CB500 four, and here for a collection of tech articles about this historically significant and mechanically impressive Honda.
The CB500 and CB550 have different transmissions and clutches. The 500 has the trans and clutch from the CB350 twin (a few of the part numbers are even the same, but essentially it's a forks-on-drum, remote clutch actuator design), while the 550 trans and clutch are patterned after the CB750 (forks on dedicated shafts, clutch actuator on clutch, both as with every Honda since). The CB500 grew out of and represents the tail end of the 60s era, whereas the CB550 bears the imprint of the beginning of the 1970s.
Fun fact: At this engine's 9500 rpm redline, the piston and connecting rod travel the length of the cylinder more than 300 times a second! Boggles the mind, doesn't it?
Avoiding short rides will save your vintage Honda's exhaust system from premature rust-out.
The CB500 four I rode in the 70s and 80s had 92,000 miles on it when I sold it after just three years' ownership and had received only a re-ring when purchased at 12,000 miles and regular maintenance thereafter.
I have well over 100,000 miles on the CB500/550.
The pistons and cylinders of the CB500/550 engine were assembled at the factory to a closeness that is equal to one-fifth the thickness of the average human hair (i.e., 0.0005"). Generally speaking, automotive machine shops go "deer in the headlights" regarding this specification. They cannot fathom this kind of precision. Beware.
Don't disrespect the career mechanic's knowledge about the CB500/550. There are many things to know and resources to take advantage of in fettling these machines. Even though they are Hondas. And relatively small.
Because the carbs--especially the 71-77 models'--are made of a zinc-based alloy, when cleaning them one needs to be careful as to methods and dip time to prevent severe chemical oxidation.
As with most vintage Hondas, if the throttle cables are not carefully routed and the throttle clearance not adequate, the engine can unexpectedly speed up when turning the handlebars.
The fourth-best thing you can do to your CB500/550 front disc brake (after switching to silicone fluid, putting in full-metallic pads, and killing squeal with pad gaskets) is to chuck the master cylinder's rubber cushion and fine-tune the lever clearance. Doing all these things together positively transforms the front brake. My CB500 has the best front brake of any bike I have owned, better than all but the most modern bikes I have encountered. And I'm still on the very adequate original hoses.
Fun fact: The pistons' rings rotate in the cylinder at a speed that is believed to be approximately 1/100th that of the engine's rpm, or about 95 rotations per minute at a 9500 rpm redline. No wonder the rings wear so much on their bottoms.
As just mentioned, it is very easy to solve disc brake squeal. Simply insert thin cardboard behind (on the piston side, obviously) the pads. That's all it takes and it will last until atmospheric conditions affect the cardboard, or it becomes over-compressed, say a year to two years. I make mine from Grape Nuts boxes. If you can find a coated cardboard, that will last longer.
The factory recommended service intervals for this bike are just 3500 miles. In today's world, this is high-maintenance.
Outside of extreme use such as racing, the transmission gears' teeth do not appreciably wear. It's the engagement "dogs" on their sides that wear and that can necessitate eventual gear replacement.
Tracking gear dog wear is important because they do so much work, and especially because production tolerances result in not much more than 50 percent dog engagement.
As with most analog instruments, the speedo and tachs are the least accurate at the extreme ends of their ranges, beginning and ending.
Using "premium" gas in this bike will result in more than normal combustion chamber carbon buildup. Honda's recommendation of 91 octane is faulty and is likely an error of using the Research number, something Honda has admitted doing. Use premium gas only if you have to because of a compression increase.
Remove those locktabs from your carburetors. You shouldn't have to use a chisel on your carbs.
The reason the carburetors are so heavy is they are made of a zinc-rich alloy. Zinc alloy isn't necessarily softer, but it is much heavier and extremely chemically unstable. It decays/corrodes easily, putting all of these carbs at risk. Easily a fourth of the ones I have got in for rebuild needed replacement due to badly corroded jet towers.
Fun fact: The CB500/550 cylinder head reaches a temperature detectable at the cooling fins of more than 300 degrees F.
As with most vintage motorcycles, the tires normally lose about five psi pressure per month.
The charging system's normal breakeven point is 1300 rpm (with the headlight off).
Unless abused, the clutch will last the life of the bike.
A properly cared for drive chain can last 25,000 miles.
The ignition points are designed to last 20,000 miles.
Fitting 2.2 ohm coils and/or a more powerful headlight will not do anything bad to this motorcycle despite what some forum "experts" say.
The voltage regulator should be adjusted to provide the charging system's full potential.
Given normal ignition system maintenance, the condensors will seldom if ever need replacing.
Beware of fuel economy expectations. The industry has avoided being specific about fuel economy for a very good reason.
The quartz headlight from a CBX1000 fits this bike. But replace the H4-spec incandesent bulb with an H4-style LED bulb.
The spark plugs don't need anti-seize, but they do need to be carefully threaded in and very carefully tightened.
Fun fact: The CB500/550 is blessed with a massive market of reasonably-priced used parts. If this model ever gets any love this will likely change and the prices escalate.
If the starting system is properly maintained, the start button will never overheat and fail. Forums claim this happens, but I have never seen it.
The standard equipment handgrips are super-aggressive and not very comfortable even with gloves on. Honda's earlier version as on the CB450 look very similar but are gentler on the hands.
There is nothing wrong with the stock wiring. Replacing most of it with a computer that will likely last only a tenth as long seems foolish and an unnecessary complication of what is a very simple, effective stock system.
Fun fact: The US dealer purchase price of the inaugural 1971 CB500 four was right at $1000.
The electrical connectors will give problems. The very first year CB500 had Molex style, which are much more delicate and prone to failure than the later Canon style. But even those later plugs will need attention. The individual bullet connectors also. The open backs of the Canon plugs invite corrosion. Fully eighty percent of electrical troubles on vintage Hondas are due to this.
The steps to take are to completely disassemble the Canon plugs (this requires special tools) and after cleaning reassemble and solder the terminals to the wires. Then when reconnecting the plugs, fill with nonmetallic grease.
The front fork when lifted off the floor to test steering bearings should not simply flop against its stops. There should be a small amount of resistance.
Due to the period's plated valves, they wear out in a very short time, usually within 15,000 miles, reducing cylinder compression as a result. This plus cylinder wear is why many of these engines do not produce the factory as-delivered 170 psi cylinder compression. And this engine's valves cannot be refaced. A 1971 Honda bulletin describes the plating and prohibits refacing.
The intake valve guides will last a very long time, the exhaust guides will not, but will still go fairly long.
Whether disc or drum, brake squeal is caused by high frequency oscillation of the friction material. Attempts to eliminate squeal by altering brake part surfaces will have no effect.
Use only factory Honda fork seals and real, actual fork oil--not ATF.
Fun fact: Honda never put either fish oil or ATF in their forks.
The rear brake shoes will last many times more than the life of the bike. If not, you have inferior parts or damage, or you are over-using the rear brake.
Fun fact: The "domestic" (i.e. Japanese market) CB500 came with a red warning light mounted to the top of the steering stem that lighted when the rider exceeded 80kmh (50mph). That is still the country's default speed limit even to this day.
Most riders over-tighten their drive chains. Almost everyone lubricates the chain improperly also.
Removing the air filter and its housing will lean the carburetors by five main jet sizes.
Riders of the CB500/550 seem largely to be unaware of how the bike is to be ridden. You don't ride it like a pickup truck. There is very little power developed in Honda's high-revving smaller fours below 5,000 rpm.
Fun fact: The disc brake's caliper piston retracts after brake application due solely to the force of a flexing square ring.
The bike normally loses between one to two volts electrical pressure from one end of the wiring harness to the other. This happens as the wiring's crimps age. In some cases this will affect ignition and charging system efficiency. Then the connectors should be rebuilt and/or the wiring harness replaced. Replacing wire harnesses has become almost standard in repairing electrical issues on the fifty year old bikes.
Despite inane forum drivel, this engine's cylinder assembly or head do not need to be machined, or specially-sourced o-rings employed, in order to get a good head gasket seal.
An aftermarket ignition system will improve engine performance only if the original system was misadjusted, worn/failed, or contained non-original parts.
Carburetor rebuild kits will ruin your carburetors. Buy the few needed parts individually.
The change to the cam cover that pinned the rocker shafts to stop their rotation is not part of a recall and not a defect. Nor is it necessary to fit this later cover, though it is a theoretical advantage.
It is not necessary to retorque the head after an engine rebuild. Honda has never advocated this.
Fun fact: The domestic model CB500 came with a horn button that could be pushed sideways to flick the headlight on momentarily for "flash-to-pass" purposes. Many other later domestic and Euro model Hondas continued incorporating this feature.
The PD series carburetors found on the final couple years of this bike are good carburetors and the easiest of all Honda multicylinder carbs to rebuild. Forums of course say the opposite.
The rubber washer at the rear brake torque arm goes on after the arm, not before. This is a common error.
This bike came with what today is considered very narrow wheels and tires (narrower even than those on the CB450). The machine is designed to suit them and putting wider tires will alter the bike's pleasantly neutral handling.
It is very dangerous to "recam" your rear brake actuating arm. It can cause the brake to lock up.
This bike works very well with Shinko tires. You do not want to ride enthusiastically on the stock rib front, and over-siped rear, tires.
Sta-Bil will prevent the carburetors from having to be rebuilt each season. One more thing forums get wrong.
Honda ran out of the needle jets and jet needles for these carburetors years ago. The float valves are almost gone now too and where found demand a very high price. They're worth it, though. The aftermarket equivalents are really bad.
The bike doesn't have or need a fast idle system. Properly tuned, the bike's cold idle will be 800-1000 rpm and hot idle at or a little above 1100 rpm.
Fun fact: A CB500 in excellent unrestored condition fetched more than $6,000.00 recently. Though that sounds like a lot, it's not that much considering the money that has to be put into one of these bikes to make them merely mechanically sound, let alone cosmetically nice.
Both the 500 and the 550 will accept slightly modified CB750 pistons for a resulting 600cc displacement. The 500 can get there by using a 550 cylinder assembly. With a little finagling it will fit.
One of the benefits of increasing the compression in this engine is it makes up for the lost compression resulting from altitude.
The CB650 cam can be fitted to either the CB500 or CB550 and offers a slight power benefit, but requires changes to the tach drive (mandatory) and tach (optional) also.
I really appreciate the aluminum handlebar switches. The later Honda models' plastic ones are alright. But the old ones have a more substantial feel and are more durable long-term.
This bike's front brake responds well to the change to silicone fluid and full metallic pads.
The tank petcock is one of the few (possibly the only?) low quality parts on this machine.
Unlike the other 70s fours, the cam chain on the CB500/550 is best adjusted with the engine running. The cam chain tensioner has a slotted screw that is turned counter-clockwise to increase tension on the chain. Forums disagree with this.
Set the carburetors' pilot screws a little on the rich side for best throttle response.
The carburetors are easily enlarged internally, but not by boring.
The tires on these bikes are always under-inflated. Run low 30s on the front and mid to high 30s at the rear.
Never pressure-wash your bike. The OEMs have warned against this for a long time, with good reason.
The CB500 and CB550 are seriously overbuilt. They're extremely durable, hard to break.
A heavier engine oil makes the 71-73 CB500 model shift better by reducing the 500 transmission's unusually high shift-drum-to-shift-fork friction.
Fun fact: In many ways, we advocates of fifty year old SOHC Hondas, machines representing a bygone technological era, are like pushrod Brit bike fans in our love of something that defies logic and reasonableness. Though a generation may separate us, there are significant parallels.
The CB500 has a crankcase breather that simply goes out to atmosphere. The way it should.
The CB500's clutch activation works best when the cable is OEM and well lubed, and the lifter mechanism is greased, not excessively worn, and is properly adjusted.
Adjust the valve clearances to 0.005" (0.13mm) for best results.
Switching out the rear brake rod for the cable from the early XL250 will reduce rear wheel hop.
The CB500 has a bimetal clutch pushrod. Mostly aluminum with steel at its tips, this design permits the clutch to stay in adjustment when the engine is hot. The final year of the CB450 and the eventual CB500T has the exact same part. This pushrod is hard to find today.
In the US, the final year 500--the 73 model--received a number of parts at the factory that would appear on the next year's inaugural CB550. The reangled speedo and tach and the larger tailight are examples.
A modern o-ring or x-ring drive chain cannot be fitted to the CB500/550 as the chain's greater width rubs on the engine.
It's difficult to fit inline fuel filters to this bike, but it can be done. It's best to retain the factory fuel line routing.
Use good, factory Honda fuel line. If your fuel hose needs clamps, it's poor quality or the wrong size or both.
Fun fact: The CB500/550's intake valve originated in the first-year CB100.
The later crankcase recirculation apparatus inside the air filter box destroys the stock type paper air filter. Get rid of this setup.
Ethanol will not hurt your bike, least of all your carburetors. The ethanol scare is a stupid myth.
Avoid Marvel Mystery Oil. It's amazing that this has to be said. What possible good is pouring baby (mineral) oil into your tank?
Don't use those aftermarket oil filter bolts. The oversize head encourages overtightening. If you want a more durable bolt, use the beefier one from the GL1200.
You absolutely must use a 6-point wrench on the oil filter bolt.
Half of the Honda SOHC fours out there are missing the oil filter washer. It sticks to the filter and gets unknowingly tossed with it.
Of course, the CB500 and CB550 both benefit from the better high pressure trochoid type oil pump, as opposed to the plunger and gear type pumps found in the earlier singles and twins.
I have available how-to books on rebuilding both the early and late carburetors. Check 'em out 😎
The rubber intake manifols ("insulators") are available from both Honda and the aftermarket.
Annoyingly, the CB500/550 throttle has one of the longest rotational distances of any Honda. But it's easily remedied, and for just pennies.
Fun fact(s): In 1971, the year of the CB500's intro, Charles Manson was convicted; Muhammad Ali lost a fight; Starbucks, Amtrak, FedEx, Cup-O-Noodles and Disney World all debuted; Elon Musk was born; the laser printer was invented; and a certain Dan Cooper jumped out of a Boeing 707.
The CB350F/400F, the late CB550, the CB650 and the late CB750 are the only 70s SOHC fours with a fast-idle system.
Fun fact: Honda makes their replacement electrical connectors available but it is kind of a secret--even to dealers--due to their being listed in their tools bulletins, not in any parts publication.
The otherwise very efficient vibrating point voltage regulator can be upset when its mounting to the frame is not perfect. There is a factory bulletin on this.
The engine's cylinder studs were put into the crankcases at the factory with some kind of adhesive that only a half hour in a 500 degree oven will overcome. Honda actually issued a service bulletin warning about attempts at stud removal.
You shouldn't need to remove your carburetors frequently but to make removal easier substitute the intake manifold studs for bolts. See my video on carburetor removal.
The carburetors employ a messy, inconvenient through-the-screw float bowl drain system. Moroso sells a cup designed for old-school V8 carburetors that helps. But it's still a pretty sketchy deal.
Stock Honda control cables are vastly superior to aftermarket ones due to their overall quality and their smooth plastic lining.
Take that silly, recall program, pretend-lock off your fuel tank. At your own risk, of course. Don't sue me.
Fun fact: Even my wife, who has no knowledge of or affinity toward motorcycles, says of the CB500, "This is how a motorcycle is supposed to look."
The centerstand is ridiculously easy to use. But you must give up trying to jerk the bike up. Here's a video showing how. Of course, you're not riding wearing sneakers, right?
My favorite tank bags are the kind that attach using magnets. I have two different size magnetic bags.
After having ridden and serviced countless far more modern bikes, I still prefer my CB500.
Very nice reproductions of the factory exhaust are available. The exhaust is an important part of the appearance of this bike.
The standard SOHC four ignition system is one of the most difficult for DIYers to adjust properly. Far from being inuitive, adjusting it is an art. The results are well worth the trouble however.
Factory Honda ignition points are very hard to find now. But they're the best in the industry.
A Dyna ignition is a good alternative, but it does not add performance and unlike the stock system it will eventually fail.
You don't need to add a relay to this bike, for headlight or ignition purposes. Nor do you necessarily need a relay to have a loud horn.
The CB500/550 engine positions its cam chain guide differently than in any other 70s SOHC four Honda.
Excellent reproductions of the factory cylinder head and base gaskets are available from Cometic. These are much better quality than any of the other brands.
Fun fact: This was alluded to above, but the CB550 cylinder assembly having slightly larger sleeves will fit onto a CB500 crankcase without machining the crankcase, after machining a few thousandths off each sleeve's o.d. This combination permits the 500 to be made into a 600 via 61mm pistons.
The increase to 600cc boosts torque in the lower rpm register, broadening the powerband, a very welcome thing.
The CB500 and CB550 (and CB350/400F) primary transmission connecting chains lack a tensioner, leading to driveline snatchiness, the more as the chain wears.
Fun fact: Petersen Publications' (Motorcyclist magazine) 1973, 282-page classic, "Motorcycle Repair Manual", has a CB500 on the cover along with its owner, Petersen's then Art Director Paul Halesworth. Look closely and you'll detect that the bike is modified. It sports a GL1000 front fork, BMW handlebars, shortened turnsignals, shortened mirrors, dual front disc brakes, Dunlop K81 tires, and it appears to be missing its centerstand.
CB500/550 engines not in the best condition or tune can exhibit some rattle of their primary chains.
Use K&N air filters if you must. I do myself. But realize you're trading engine longevity for the sake of performance.
Another potential but far less common source of engine noise at idle is a loose clutch gear. The steel gear is riveted to the aluminum clutch basket.
The CB500/550 is smoother than its bigger brother the CB750, but it is still a little rough-edged compared with today's more refined machines. And most of that roughness is simply non-counterbalanced, 180 degree four cylinder buzziness.
I hope to have an engine rebuild how-to booklet available soon. 😎 Keep an eye out on my catalog page.
Fun fact: Cycle magazine said in a period test, "The new for 1971 Honda CB500 Four took all the 750's fine attributes and focused them into a smaller, lighter bike that in many ways is better than its much-lauded forebearer."
The CB500 is believed to be some 80 pounds lighter than the 750.
I use only factory oil filters. Unlike the others, they have always been quality parts.
This engine does not need an oil cooler.
The normal engine idle is 1000 to 1200 rpm. If this can't be achieved repairs or better tuning is needed.
There would be a lot fewer conversions to aftermarket tapered type steering bearings if the original bearings were maintained properly.
The CB500/550's rocker arms are chrome-plated. It's not unusual for the rocker arms to fail this plating, leading eventually to camshaft damage.
Fun fact: The CB550 was morphed into the CB650 in 1979. Architecturally, it's the same bike. But the engine underwent a lot of revision, including not only a larger cylinder bore but also more stroke. The valves are the most surprising. They're almost 50 percent larger!
The later CB450 and CB500T would share many parts with the CB500 four, just as both bikes also got parts from the early CB750.
Though inconsequential, the CB500 and CB550 like all of Honda's 70s inline fours have alternators that do not charge at an engine idle. Between 1969 and 1983 all of Honda's inline fours had this kind of charging system. Far from the defect forums label it, it is a very robust system.
As with other vintage Hondas, this bike lacks the capacity to support heated clothing. Gloves, maybe. But not much more.
I have run a 552 turnsignal flasher on every Honda I have owned.
I have run an onboard ammeter on every Honda I have ever owned.
The starter motor, being very understressed, is a very long-lasting part.
A four-way "hazard" flasher system is easy to make yourself and it too can be designed around a 552 flasher.
The CB500 four's electrical system of course has only a single fuse. It is wise to carry a spare.
If you're smart you'll avoid aftermarket engine gasket kits.
Fun fact: The CB500 four was made not with the CB450's front brake (which was actually the CB750's) but with its own unique brake.
Probably not everyone is aware that the rear brake light is adjustable to compensate for drive chain and brake pedal changes. Proper adjustment will ensure it doesn't come on by itself and drain your battery.
Be sure to periodically inspect and test your spark plug caps. Make sure they're tight on their wires, and replace them when they grow more than 5K ohms in resistance.
To avoid tearing out the countersunk Phillips screw holding the speedo cable, give it a couple of smart taps with a hammer and straight punch before attempting to remove.
Speaking of hard-to-remove fasteners, it isn't good practice to put thread locker on the fork's damper rod bolts. You may need a torch to get the bolt loose next time, and its socket ("Allen") head is very easily damaged.
The o-rings at the intake manifolds need replacing periodically. Though Honda used the same o-ring here as at the valve inspection caps, a slightly thicker one is preferred.
Fun fact: The oil pressure switch originally had an orange top that leaked. Back in the day, dealer mechanics substituted the black-topped 750 switch as a solution. Honda later superseded the part to the 750 part.
The wheel bearings are easy to replace, not even requiring any special tools except those for removing the two threaded seal retainers, which tools are available on the aftermarket. Don't use a chisel on the retainers!
The threaded seal retainer on the rear wheel is uncharacteristically for Honda a left-hand thread, and steel. 4into1.com sells a replacement.
It is necessary to remove the primary shaft when separating the engine cases. This is best done using a slide hammer but it can also be done through careful use of a brass punch from the opposite side.
As with any part of the engine including the cylinders and head, the best practice for separating the cases is to intelligently use pieces of wood to shock and to leverage the part. Don't hammer on the engine cases.
With no fuel gauge, of course, keeping an eye on the odometer is wise.
The originally equipped swingarm bearings are sintered metal. Aftermarket replacements are bronze. There was a special factory tool (see the service bulletin) for removing the bearings. It is easily replicated.
Fun fact: In 1974 the new CB550 was introduced. In 1975 US lighting laws changed and the bike got an always-on headlight.
The tach drive seal (and o-ring) must be replaced periodically.
The tach and speedo cables should be gently tightened at their instrument ends using pliers. There is actually a Honda bulletin on this.
The factory's front brake cylinders' rebuild kits are superior to the aftermarket ones.
The factory snap ring pliers used when rebuilding the front brake master cylinder are long discontinued. The aftermarket offers substitutes. It continues to be a ticklish job getting that snap ring out no matter which tool is used. The CB500/550 is uniquely difficult.
The CB500/550 carburetors are among the easiest to synchronize.
Fun fact: Cycle World in 1971 called the inaugural CB500, "Perhaps the finest example of superb engineering and deluxe features we've ever come across. It just might be the best looking Japanese bike in production."
There are conversion plates available to mount a single K&N air filter to the CB500/550 airbox. I made my own (much larger) version and it works well.
The alternator is very trouble-free. The only real maintenance need is regulator cleaning and adjustment, and that maybe once in the bike's lifetime.
One good way to screw the alternator up is to adorn the bike with one of those decorative finned alternator covers. Since all three screws have to be removed and replaced to install it, if done with the alternator still on the engine the field coil can easily shift in alignment, leading to eventual damage.
Monitor your drive chain by occasionally doing the pull-the-chain-off-the-sprocket test.
There are a lot of piston kits and camshafts, oversize valves, all of that out there for this engine. Among these choices are Dynoman (JE) and Wiseco pistons, which unlike the others come with quality, Japanese rings.
There are racers who are getting between 70 and 80 hp at the rear wheel out of this bike--more than double the stock power!
Fun fact: Cycle World's Peter Egan said he sold his Norton and bought what he had been wanting for some time, a CB550. He said, "It feels compact, solid and secure. In full acceleration it woofs through the gears in a series of smooth, euphonious lunges with enough spirit to be fun. Very fine engineering, a jewel-like engine, long service life, beautiful shapes and a plethora of convenience features all wrapped up into a machine whose appearance and performance transcend its individual parts."
A number of people (including myself) have found it easy to retrofit the CB650's primary chain tensioner into the CB500 and CB550. A bonus is that the CB650 oil pan that must also be installed adds oil capacity.
Those with some history with the CB500/550 appreciate the early, traditional keyswitch. Though at times seemingly inconveniently placed, it has a reputation for durability and functionality the later upright switch lacks.
One of the charms of the CB500/550 is the ability to rebuild the engine's top end while the engine is still in the frame.
The CB500 of course is without any of the features many consider safety devices such as the starter lockout, clutch lever override, and the sidestand bounce rubber that would appear later on the CB550 and other Honda models. It would seem the CB500 was made in an era of taking responsibility for yourself.
Happily, this bike also escaped having Honda's earlier design selenium rectifier, a substandard part that continued to be fitted to for example the CB450.
Fun fact: Cycle World also wrote, "You know, most people really would never need any more bike than this. It does everything just fine. Honda has embraced a kind of architectural classicism that has paid tribute to both British and Italian design, with just enough Honda thrown in..."
There are no self-cancelling turnsignals on this bike. They wouldn't appear on Hondas until well after the CB500/550's era, into almost the mid 1980s.
More "throwback city" specs: incandescent turnsignals, naturally. Though some people are fitting LED bulbs, there doesn't seem to be a lot of benefit to that. Failure of the original bulb is very rare. I have literally very near 100,000 miles on CB500s and have never replaced either a tailight or turnsignal bulb.
The horizontally-positioned crankcase drain plug has always seemed an anomaly. Different (quirky) enough from the other SOHC fours that it added to the bike's uniqueness.
The handlebars are perfect. Sure, a lower bar--even just one slightly lower like what was apparently the Euro spec--would enhance the bike's profile. But it's not to be traded for the very "right" ergonomics of the original part.
There is no such thing as "break-in" of this engine when good parts, professional machining, and correct procedures are followed. This has always been true of Hondas. The rebuilt engine, just minutes after its first start, will have the highest compression it will ever have. Or very near it. If your engine rebuilder says your just-rebuilt 140 psi engine needs break-in time to get to the normal 170, you have, sadly, got definitively unprofessional service.
Speaking of compression, if you are at altitude, you can expect about a 5% loss of compression for every 1800 feet elevation.
Nearly every 70s Honda SOHC four I have seen, especially those pictured in magazines, have had the front fork clamps and/or the handlebar clamps tightened incorrectly.
A 16-tooth countershaft sprocket really wakes up the potential of this bike.
Everyone adjusts the clutch wrong on 70s Honda fours. I have never seen a CB500 or CB550 clutch adjusted correctly.
Don't use an adjustable wrench anywhere on this bike, least of all on the rear axle nut. Get the correct 26mm wrench.
Although scarce, the factory cam chain is still available and easy to replace when using a 70s CB450 stake link.
The rear axle should be liberally greased to prevent its rusting.
Though the left crankcase (countershsft) cover can be removed and replaced without removing the left footpeg, it is tricky.
Not all of the CB500/550 cam cover's bolts and screws get sealing washers. The official manual shows which do, but basically, it's all that are inboard of the rubber sealing gasket.
Speaking of sealing washers, be sure that the aluminum washer is place properly under the beauty covers at the ends of the cam.
The left and right cam cover beauty cover screws are unique. If replacing them, you must use the factory screws. They are a special length that is not replicated in any fastener sold on the aftermarket.
My own bike has its cam timing set to an actual 10 degree BTDC intake open time. Much experientation has put it there.
Though the factory ran out of spare valves long ago, decent aftermarket ones are available and longer-wearing stainless steel valves also.
One of my trade school instructors rode a CB500 four and probably influenced my preference for the model.
Invariably, a CB500/550 will exhibit a 0 BTDC intake timing. Yes, 0, or even less. This is due to the combination of worn camshaft and cam chain.
The CB500/550 starter clutch is relatively trouble-free but can in some cases develop the same problem that Honda's 70s twins do--loosened screws.
Don't put socket head (Allen) screws in this engine. Four reasons. They are too easily overtightened. Screw kits invariably include many screws of incorrect length. The screws often are stainless steel and react with the aluminum engine by inviting corrosion. And they look wrong.
Fun fact: Bike magazine called this bike, "One of the finest balances between performance, economy, and handling quality in today's motorcycling arena. We consider it to be one of the better bikes to emerge from Honda's design team in recent years."
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