CX500 / GL500 / CX650 / GL650


There is additional information on the History and Buying Tips pages.

1 What fuel should I use?

Honda engines since the early 1970s were designed to run on what used to be called 2 Star, and now work perfectly on unleaded petrol. It does no harm to infrequently use an additive such as Redex.

Fuel tap position : horizontal = off. Arm downwards = main tank. Arm upwards = reserve.

2 Should I use oil additives?

No. The clutches are "wet" i.e. they operate under general lubrication splash from the engine, and an oil additive which is designed to make the engine oil more "slippery" may well cause the clutch to slip as well.

3 How often should I change the oil and filter?

Every 3,000 miles. Always change both, and do not use pattern oil filters.

4 What engine oil should I use?

Any good quality mineral oil in the 15w-40w range, unless you have a vastly hotter or colder climate than usual. For donkey's years I've used bog standard oil from my local supermarket, and after stripping the engine, found it completely clean inside.

Standard mineral oil is best in these engines. It's worth remembering that modern synthetic, part-synthetic or any oil with additives is likely to make the clutch slip. This is because the Honda clutches are designed to run 'wet', i.e. in general lubrication splash from the engine.

5 What are the main weak spots of the CX/GL?

Given good maintenance and regular oil and filter changes, the engines will pretty much go round the clock (and in some cases, more). The primary cause of engine failure is not changing the cam chain when it starts to slap about and the tensioner is at the end of its adjustment. This chews away aluminium from the engine casings and the shavings contaminate the oil supply, leading to premature big end failure. The stators tend to fail at about the 40,000 mile or 20 year old mark, as do the mechanical seals. These three jobs are usually done as one operation (the "triple bypass").

6 What are the main settings, pressures etc?

Print out this quick-reference sheet.

7 What fuel consumption can I expect?

All the CX500s I have owned (except the Turbo) have averaged 54 mpg under all conditions. This is UK (Imperial) gallons at 8 pints per gallon.  A, B, Z and EC models will easily cover 160 miles on a complete tankful and nursing the engine could probably squeeze 200 miles out of it. Custom variants have much smaller tanks and 110-130 miles seems to be their maximum. However when running onto reserve, all CXs give only the ghost of a warning, and you have to switch tanks particularly quickly.  So it's worth practicing this.

The Turbo gobbles fuel to the tune of between 30 and 45 mpg depending on how hard you ride it. 35-38 mpg would be a good average.

8 Are these bikes comfortable to ride?

Very. They have big fat saddles and especially, the pillion seat is extremely comfortable. A fairing or windscreen is advisable at high speeds.

9 Are there any handling vices?

Only that if you get the bike airborne, it will roll sideways as the bike tries to rotate around the crankshaft. So don't go bridge jumping on a CX or GL. Apart from this, I've never found any handling vices. Don't listen to stories that shaft drive bikes are difficult to ride. Once you've had a no-maintenance shaft drive bike, you'll never want another oily, expensive and messily adjustable chain-and-sprocket bike.

10 At what mileage do problems start to occur?

40,000 miles for cam chain, mechanical seal and stator. These are not difficult DiY fixes but all are engine-out jobs and usually done together, the famous CX "triple bypass" operation.

11 I've heard about the infamous CX cam chain problems, how true are these stories?

This is not exactly an urban myth but the problem is popularly misunderstood. Only the very earliest earliest batch of CX500Zs had the design deficiency which made the cam chain tensioner blade snap. This was quickly fixed by Honda and frame numbers after 2034366 are fine. Earlier models had modifications fitted and unmodified engines are extremely unlikely to have survived this long. If your bike dates from late 1970 onwards you should be quite OK, but check the engine serial number.

12 What performance can I expect?

The A, B, Z and EC 500s are quite happy to cruise at anything between 50 and 80 with a top on-the-flat speed of about 105 mph. The Custom variants, having smaller rear wheels, accelerate better from rest but are not so comfortable at speeds exceeding 70. The 650s will cruise at up to 90 with a top speed of about 115 mph. However, I don't advise running an elderly engine at more than 70% power for long periods.

The Turbos are massively more powerful. The 500 will pull 120 mph and the 650 will wind up to at least 140, with astonishing acceleration.

All the models will pull away from 30 mph in top gear and generally have huge amounts of low speed torque.

13 What revs do these engines handle?

All the CX and GL range are designed as high-revving engines, usually redlined well after 9,500 rpm. It is perfectly normal to cruise them at between 6,000 and 7,000 rpm for long periods. I once cruised a fully loaded CX500 at 85mph for almost three hours on the autobahn linking Germany to the Czech Republic.

The ZAB and EC 500s do 6,000 rpm at 70 mph but the 500 Customs and GL500s rev higher - about 6,250 - due the small 16" rear wheel. The ZAB 18" rear wheel drops straight in, if you want to reduce the revs at motorway speeds.

The Eurosport 650s and 500 Turbo do a shade under 5,000 rpm at an indicated 70 mph. If anyone has figures for the GL650 and 650 Turbo, please tell me. Note that the 650 engines are nothing like as smooth-running as the 500s, and vibrate considerably more. It's a joy to trundle a fully warmed-up 500 along at 30 mph in top gear and listen to the deep purr of the engine.

A rider brought up on slow-revving engines will often think that the CX/GL motor is revving its guts out. Don't worry, it isn't.

14 Are spares a problem on these 20+ year old bikes?

Whilst tyres, disc brake pads and rear brake shoes, plus filters and consumables, are readily available, some of the items which are particular to these models have been discontinued by Honda. However, they are all easily obtained from motorcycle breakers or within an owners' club, as between-member swaps. Ebay is another fertile source of both complete bikes and spares.

The only spare which is unobtainable is the front mudguard but the pattern one most of us use is a very close match for the original. Only a close inspection shows the slightly more square shape.

Entire engines come up regularly on Ebay. You are advised to get a spare pair of HT coils and either a CDI unit (500Z, A, B, C) or spark units (GL500, 500 Eurosport and all 650s). Saddles and Honda original exhaust collector boxes (aka H-boxes) are also rare.

15 Ok then, what spares should I accumulate?

(*) essential; (+) important; (#) useful

For Z, A, B, C and D models, a CDI unit; for all others, a pair of transistorised spark units * starting to get rare


High tension coils (for CDI or transistorised, as they are different) * if one fails you are reduced to being a CX250


Saddle (Z=A=B; C, GL and EC are all different) # rare, and the steel ones rust and disintegrate


{ Exhaust collector box, also known as H-box * } all the exhaust components are rare

{ Downpipes +

{ Silencers +


Side panels (Z=A=B; C, GL and EC are all different) # you can lose or break one


Rocker box cover retaining bolts (Z=A=B=C=D=GL; EC500s = all 650s) + these snap sometimes and you can't ride unless the covers are secure


Gear lever and rear brake pedal (Z=A=B; C, GL and EC are all different) # easily accident damaged


Swinging arm (Z=A=B=C; all ECs and GLs are the same) + these rot underneath and spares are scarce


Water pipe retaining arches (pair) + these are esily broken and hard to find as they are unique to the CX/GL


Headlight and chrome ring (Z=A=B; C; EC500s = EC650s; GLs) # rare


Stator (Z=A=B=C with advance pulsers; others, without) # even if it's a dead one, you can get it rewound in advance, ready for a stator change


Rear engine case # as you can fit it with a new mechanical seal and stator in advance of a triple bypass, saves you days of waiting for parts to arrive

Left and right handebar switchgear (differences are cosmetic, but Z=A=B=C; GLs, ECs and 650s are the same. Also, the 250 and 400Ts and Ns (Dream, Superdream in the UK) have the same switchgear as the ZABC. Note that different countries have different lighting requirements, for example in some countries the lights have no 'off' switch) #

16 Going on a long trip - what specific spares should I carry?

Clean, tested (or new) spark plugs

CDI unit for ZABC models / spark boxes for EC, all 650s

at least one HT coil and spark plug cap

Clutch cable

Throttle cables (if you take just one, make it the 'open' cable)

Front brake and clutch levers (in case your bike falls over, especially on the ferry)

Enough tools to be able to replace all the above spares!

If you didn't find what you want on this page, browse the main page. If you still can't find the answer to your question, or simply want to comment on the pages, you are welcome to email me but please delete the 'z' from the email address.