CMS-Japanese Motorcycle Supply Parts

Buying Guide: Honda CX500, CX650, GL500, GL650

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So you're considering buying a CX or GL variant. They're a great line of bikes and are generally quite reliable machines, though a lot can happen over 30+ years and varying degrees of care from previous owners. Here's a list of things to keep in mind when you're looking at a bike.

Pre-inspection checklist

Bring a friend

It can really help to have a second set of eyes and ears when looking at a bike - and different levels of experience can be a good thing, as both more and less knowledge than you can result in questions you didn't think to ask.

Do your research

Get an idea of what the bike you're looking at is worth before you rock up to check it out in person. Not sure? Ask on a forum, and make sure you specify where you are in the world. A CX500 in North America is worth a very different amount to a CX500 in Australia, given the same condition and mileage. Make sure you know what features SHOULD be on a bike of the age and model that you're looking at - a lot can happen in 30 years and if something has been changed out it can alter the value, for better or for worse. You might also be able to pick up on some things - like a GL500 with a CDI box? That's had a replacement engine from an older CX500 somewhere along the way, which would suggest a closer inspection would be warranted.

Be objective

Try not to buy the first bike you set eyes upon. Sometimes it really is the best deal (or the only deal, depending on where you are) but it's easy to get carried away and look at it with a critical eye. If this is your first time buying a CX it can really help to look at a few different bikes to get an idea of what they should sound and feel like - it can be hard to tell the difference between specific engine noises that may be normal or may spell trouble if you haven't ever heard one run before.

Be analytical

How much work will it take to sort those busted fork seals out, anyway? How about a flapping cam chain? Research the known and likely problems and check out the part prices and how long the repairs would take you. If you're going to need a workshop to fix up the issues, call a couple and get some quotes on how much. Use these to knock down the price if necessary.

Be clear

Make sure you know what you intend on doing with the bike beforehand, whether it's basic transport, restoring or modifying. This will change how much certain problems matter - if you want basic, reliable transport and would rather it just working as soon as you get it finding something which has already had a triple bypass done recently would be an advantage. If you're going to be chopping the bike up and replacing most of the components, on the other hand, something which is a bit rattier and has non-functional bits that you were going to throw away anyway may not be nearly as much of a problem.

Communicate well

It can be really helpful to know what the seller is comfortable with before you rock up. Ask about taking it for a test ride if it's registered. Concerned about the engine and want to do a compression test? Politely ask about it first rather than rocking up with the tools and creating an awkward situation.

Look at cold bikes

Ideally, you want the engine to not have been started when you first come to look at it. It's probably a poor idea to grab an exhaust pipe to check this, but it's worth asking the seller to make sure it hasn't been started for at least a few hours before you see it, and ideally at least overnight. Why? The first start of the day is often the hardest and some engine problems are more obvious when cold, e.g. worn valve stem seals.

Engine checklist

Cam Chain

One of the main bugbears of CX/GL maintenance. Some bikes - and this varies from country to country - have a manually adjusted tensioner, and some have an automatic tensioner. Any long-term twisted twin owner should know when the chain was last changed, and if there's a manual tensioner they should be familiar with the technique for adjusting the tension. If they can't tell you, chances are it's never been done in the time they owned it which could spell bad things for the cam chain.

The cam chain is one of the aspects of the triple or quadruple bypass.

There weren't any non-Turbo 500s sold in the States with the automatic tensioner. All 650s world-wide should be automatic tensioner. Australia had manual tensioners for '78 to some point in '81 - later TI bikes were auto tensioner.

Some very early bikes were part of a recall regarding the cam chain tension setup - if your engine number is CX500E-2034366 or below make sure that there are three punch marks next to the engine number on the engine case to show that the recall fixes have been carried out. Where's the engine number? Click here for a photo. This only applies to the CX500E- range of engines, all later engines (e.g. PCO1E, PCO2E) had the recall fix already applied.

If you have a particularly keen seller who will let you undo an inspection port you can check out the cam chain status with a borescope or mirror. I wouldn't adjust the tension on a bike that wasn't mine - you wouldn't want the blame for anything going wrong, imho. Anyone who has owned the bike for more than 5,000km should have adjusted the tension at some point in time and if it is a manually adjusted machine and they try to tell you that it's automatic then you can safely presume that they haven't ever done it... and start questioning what else they have missed about the bike's maintenance.


If they're dirty, they will almost certainly need an ultrasonic clean - or several of them - to clear up. Opening them up and spraying them with carb cleaner is rarely the solution. There are drop-in carbs tuned to the CX available (see Murray's Carbs), or if you don't want to do the work yourself you can send the carbs out to get cleaned for you - there are a couple of guys in the US who do that - see here.

Cooling system

The level of coolant in the overflow tank behind the engine has no bearing on the level of coolant in the radiator; if you want to check the radiator (and you should) you will need to remove the seat and tank, which is a pretty quick process and a reasonable request. There should be coolant visible in the radiator and you shouldn't be able to see any creaminess/scum/oil.

Also check for any coolant leaking down the back of the rear engine cover underneath the carburetors, particularly on the left hand side of the motor behind and underneath the chrome coolant pipe. There is a weep hole up there for the engine's mechanical seal, which is one of the aspects of the triple or quadruple bypass. Other potential sources of leakage there are the chrome coolant pipe O-rings, the gasket around the water pump impeller cover or the thermostat bypass hose at the top of the impeller cover.

Exhaust system

Start it up. You shouldn't see any smoke. Condensation, perhaps, but that won't linger in the air. White smoke (often smelling sweet) is usually coolant, black smoke is often an over-rich fuel mixture or unburned fuel and blue smoke is often oil. Keep in mind that the exhaust H-box allows exhaust from either cylinder to mix (somewhat, and depending on how rusted the internals of the H-box are), so don't take smoke coming out of the left side to necessarily mean a problem on the left. Examples of problems: Coolant could mean a blown head gasket, fuel could be an ignition problem (no spark, no burning the fuel, shoots straight out the exhaust) or an over-rich carb setup, oil could be valve stem seals or rings.

One cause of a rattly engine can be loose exhaust connections on either end of the H-box and loose or damaged bolts holding on the exhaust heat shields; it's worth checking (carefully, if they're hot...) those before writing off rattling noises as being cam-chain or other internal-engine-related problems.


The gear pattern is one down, four up - neutral in the usual position halfway between first and second. All gear should be selectable without fuss. Removing the gearbox is an engine-out procedure if there's a problem.

If you're not taking it for a test drive you can still check that the bike runs through all of the gears - pop it on the center stand and you should be able to shift through them all at idle revs. If the bike isn't running you can still check all of the gears on the center stand but you will have to have turn the rear wheel each time you shift or it likely won't engage the next gear.


Check the oil level. You need the bike to be on the center stand or balanced upright for this. Click here for a how-to. If the oil is amber it has probably been changed fairly recently. Ask the owner how long ago it was changed, and what sort of oil was used. If they can't tell you the last time it was changed, drop your estimate of how well they looked after the bike by a few notches. Black is OK and probably just needs a change. Creamy is bad and indicates water in the oil, either condensation or coolant. If it's coolant there may be a head gasket problem, or a mechanical seal/camshaft seal problem.

Also check that the oil doesn't smell strongly of gas; if it's overfull and smells like petrol there may be petrol overflowing from the carbs into the cylinders and draining into the crankcase, which is bad for engine lubrication.


If the bike has sat for a good long time don't put a new battery in and fire it up straight away - assuming it cranks and has oil that doesn't look too awful and is of sufficient quantity set the killswitch to "off" and crank the engine until the oil light goes out before trying to start it up. Otherwise the engine may fire up before oil pressure builds sufficiently and you may cause engine damage.

Need a new battery for it? Get some model numbers, prices and options on this page.

It's not unusual for a CX/GL to start up on one cylinder (usually the left) and for the remaining cylinder to kick in shortly thereafter. Idle should settle to a touch over 1,000rpm. One cylinder not firing beyond the initial startup could be anything from carbs to an electrical/ignition fault - don't assume it's going to be a quick and easy fix.

In theory, the bike should be able to start either a) in neutral or b) whenever the clutch lever is pulled in, but in practice the starter disconnect switch seems to commonly be faulty and not replaced. If the bike tries to start in gear with the clutch lever left alone, there's probably a fault and/or someone has bypassed something in that circuit.

Temperature gauge

Every bike should have one of these. If it's stock, it should work it's way to the midpoint once the engine is at operating temp. With an aftermarket one we found the engine liked to sit at or around 70 Celsius most of the time. If it doesn't work at all or works improperly it could be electrical - for example a 7V regulator could be at fault - or there could be a problem with the cooling system. Don't assume it's the most simple problem!

Weep Hole

The weep hole is designed to allow coolant which makes it's way past a faulty mechanical seal to flow out of the bike's engine, rather than into the crankcase and mixing with the oil. Click here for a diagram of how it works, or click here for a photo of where it is located.. If there's coolant leaking from the upper rear part of the motor above the starter motor/rear of the motor/exhaust H-box it could be from a number of places; if it's the chrome cooling pipe it can be tedious to get an O-ring to seat properly on, but if there is coolant coming from just behind that where the weep hole exits that means more work is required. A mechanical seal can be replaced with the engine in the bike with a bit of work, or as an engine-out procedure.

Keep in mind that a blocked weep hole is a good sign that at some point in it's life the bike had a mechanical seal which needed replacing and a previous owner - whether the current owner or another - has blocked it up either through lack of knowledge or a desire to hide the leak. If it looks like it's sealed in any way, check the oil for signs of water ingression and plan on dropping the engine so you can clear it out.

Chassis checklist


Visually inspect the front brake system for leaks, and ensure that the master cylinder functions correctly - it should not sink straight to the handlebars, nor should it be almost impossible to move. If you aren't taking it for a test ride, try rolling it forward slightly and apply the brakes to make sure that they have some effect. The bike should be reasonably easy to move in neutral; if it's very difficult to push and it is definitely in neutral you may have a front or rear brake stuck on.

Check the rear brakes as well. Some models have a hydraulic disc at the rear, which will need to be checked for leaks. Other models have a drum rear which won't be leaking but you can still check that the brake pedal works as expected and that the rear wheel spins easily when the brake is not applied.

Driveshaft and final drive

There shouldn't be any clunking noises from the drivetrain. Ask the seller when the final drive oil was last changed - it's only a 5 minute job, and if it hasn't been done for a while it should be changed out. Also ask when the final drive last had grease applied to it, and which sort of grease was used (see Which grease to use for the final drive splines?). Again, if it has not been done plan to do it - it won't take a lot of time, as removing the rear wheel is a pretty quick job on this bike (perhaps 30 minutes the first time for someone unfamiliar with the process).

Front forks

If you can take it on a test ride, try braking sharply to see if the forks bottom out. Many of the springs in these bikes are out of spec after ~30 years and might need replacing. Check to see if there is any sign of fork oil on the forks (wipe it clean before riding or compressing then look for smears or droplets) after compressing them a few times; if so, budget for fork seal replacement. Check for pitting in the swept area of the fork seals - if there's any notable pitting you'll probably need to find new forks or attempt to fill the holes, otherwise you'll ruin the fork seals in short order.

Ask when the forks were last serviced. Every single CX I have ever bought has had forks that have been ignored for years and the sticky black/grey fluid in them barely resembled fork oil or automatic transmission fluid as was originally used... so if they haven't been serviced recently plan to clean them out.

Fuel tank

If the bike has been sitting for a while the owner may not have the key; while it's hard to start the bike with nothing but a small flat-bladed screwdriver you can almost certainly open up the fuel tank on a CX500 Standard/Deluxe/Shadow without damage using one. The CX650C and CX500E/CX650E caps are properly keyed, and I don't yet have data on the 500 Custom tanks. This can be handy to ascertain just how rusty the inside of the tank is, but ask first before shoving a screwdriver into someone else's lock.

Also check the tank over to see whether there are any dents or pockmarks in the paint along the lower edges - small rough bubbles in the paint in this area may well suggest rust holes just waiting to open up and let out fuel all over your ride.

If the tank shows signs of rust you can expect that the carbs will need a good clean with an ultrasonic cleaner, as the filter on the petcock doesn't stop the rust getting through. Unless the previous owner explicitly says that they recently cleaned the carbs repeatedly with an ultrasonic cleaner or got a shop who's familiar with CX500s to do the work, expect to need to clean them yourself after purchase. The best carb rebuild kits run to $85-100USD.


Common rust points are the swingarm top and bottom and the bottom of the frame near the footpegs. Also check the inside of the pillion footpegs mount area.

If you are buying a partially finished project make sure that the frame hasn't been chopped up too badly - you can see what the stock single spine frame looks like here and what the stock GL500/CX500E/CX650E/GL650 frame looks like here. In some areas you need to provide an engineer's certificate if you make any frame modifications (e.g. NSW, AU) - worth checking that sort of thing prior to purchase in case you back yourself into a corner where the frame won't pass inspection, should you declare such modifications or have them noticed.


Here's what you don't want the tyres to look like on your potential new Honda CX500, GL500, CX650 or GL650 purchase.

Tyres should all have a date code on them that tells you when the tyre was manufactured. Anything that is made out of the last 5 years should be replaced - check this and budget for replacement! For more information on the date code and tyre assessment, check out our page here.

Electrical checklist


If the bike has sat for a long while the battery is quite likely to be dead. If the previous owner has replaced the battery recently and it works fine there shouldn't be any reason to replace it. If you're unsure, there's a number of tests you can do to check the health of the battery - and don't forget that sometimes a flat battery is a symptom of a faulty charging system.

If the seller claims that there's nothing wrong with the bike apart from a flat battery thus they can't start it, take a battery with you! Sometimes the problems run deeper than that and it's worth checking something easy like that. If you don't have an appropriately sized battery to put in the bike you could always take a larger one and jumper leads.


If you have an aversion to getting the bike home and discovering a stator problem, you can always do the stator test on the bike pre-purchase - assuming the seller is happy with you using a multimeter on the bike. This applies to any of the CDI CX500s - in some countries that's any year, in others it's any year pre-some-point-in-'81. TI CX500s, all GLs and CX650 (C or ED) are all TI and the stator only charges the battery - though you can still test it for that functionality. Not sure which ignition system you have? Click here for more information on how to tell which is which.

Replacing the stator is an engine-out job, and you'll be up for at least the cost of a rear gasket in addition to the stator. Many people also choose to replace the cam chain at the same time, along with the mechanical seal. This is referred to as the 'triple bypass' - or 'quadruple bypass' if you're doing the starter springs as well, where you change out the starter clutch springs as well. For a parts list of the triple bypass procedure see here and for the procedure itself read up here.

Replacement stators are readily available online - see the triple bypass parts list - or you can get the original one rewound.

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