< AllMoto's Motorcycle Investor mag

Motorcycle Investor mag

Six Runner

Getting the 1981 Honda CBX1000 on the road

Bought at auction, this old CBX six has had a colourful life and proved to be a bit of a project to get back on the road...

(Feb 2024, Guy 'Guido' Allen)

It all began with an unreasonable urge to add a straight six to the motorcycle shed and the model had been narrowed down to a CBX1000 Honda.

Why? Love the Benellis – or the idea of them – but I didn't want another seventies Euro project added to the already complex mix. Kawasaki? A nice idea, but for yours etc they don't hold quite the same appeal as an air-cooled six with Honda's often quirky sixties GP racing history behind it.

So we have it narrowed down to a series. Do we go first naked model circa 1978-79 (above), or second-gen faired generation of 1981-82? Two factors swung the pendulum in favour of the latter: a first-gen naked bike costs 50 per cent or more over its later equivalent and ends up as an investment vehicle; Plus I liked the idea of having the big 'grand tourer' version as it works with the sort of riding I enjoy.

Naked versions are very much on the international collector radar at the moment and are growing in value. Meanwhile a well cared-for Prolink, or CBX1000B or C, will more than likely hold its value.

Honda's CBX1000 six was publicly launched in late 1977 and an unexpected delay in production meant it took nearly a year for it to reach the market – so second half of 1978 for the 1979 model year. It pulled very positive reviews, but the delay hobbled it in the showroom. There was a lot going on at the time, such as the launch of Yamaha's XS1100 and Suzuki's GS1000 series.

Add in the obvious complexities involved with a 24-valve inline six, with a carburetor per pot, and you can understand how a fairly conservative market might have got a little shy. The first-gen pulled only modest sales, and so Honda worked on a second that it could shift into a different market segment.

Rather than just dress it up in new bodywork, the company put some serious effort in. It risked knocking a few horses off the top-end to broaden the midrange and made some small but significant alterations to the carburetor set-up.

Suspension at both ends was upgraded, moving from twin-shocks to a Prolink rising-rate monoshock at the rear. Steering geometry was altered to slow it down and the wheels were changed over.

When it came to brakes for a now heavier machine, Honda's showpiece was the fitment of ventilated discs cast in-house (an impressive undertaking at the time) combined with an upgrade to two-piston calipers all round. The previous model was effectively running Gold Wing brakes with solid discs worked by single-piston calipers.

The in-house panniers were sculpted to fit the machine and came with a key-operated one-off mounting system that worked well.

And then there was the Bol d'Or-theme fairing, complemented by the long rear tailpiece. It was a nice try, but the market still wasn't convinced.

In the USA, dealers famously quit stock for whatever they could get, commonly around 60 per cent of retail.

And so there we were, a little over 40 years later, with muggins risking a bid at auction on one of these things. It ended up in the shed.

It came with a cute story. The CBX was initially sold by Phil Crump Honda in Mildura – yes, the Crump of international speedway fame. It was owned over the years by a few people in the district who of course knew each other.

At some stage, the story goes, the bike was purchased by the wife of one of the gang, who convinced the others to chip in for a restoration including a kangaroo-hide seat. It was presented to the lucky gent as a 50th birthday present.

I got the chance to eyeball the CBX before bidding and could see it probably needed recommissioning after a lay-off. It had an aftermarket exhaust system which was decent quality but was showing signs of rust. Plus, I wasn't thrilled with the relatively clumsy pipe bends on the headers (above).

Step one was to do a basic strip (of the bike) in the back yard and get my head around what we were dealing with.

Then we did two things: sling it at my local workshop (the crew at Gassit) and order a bunch of parts, including a new exhaust system from Delkevic. The latter is a far better visual replica of the original.

Spares availability for this machine is mixed. Service parts such as filters are good, but everything else is patchy.

This turned out to be a pretty big job and I was fortunate enough to strike a mechanic (Brett) who was up to the task. In the end, we had to strip down and clean out the carburetors (a huge undertaking), replace the plugs and caps, do the usual filters and fluids, plus rebuild the brake calipers and change the fork seals. Oh, and then there were the tyres, plus chain and sprockets. We're talking about somewhere around Au$4000 (US$2600, GB£2000).

The bill didn't come as a big surprise. While you'd hope you could just collect the bike, throw in fresh fluids and ride off into the sunset, machinery at this level that's been left to sit is going to cost money to recover. I have a mate in the classic car world who likes to remind me (when I grizzle about the running costs of my V12 E31 BMW) that when you get into high-end machinery, no matter how small the purchase price, you can expect to cop high-end running costs. He's right. The trick is to keep it down to a dull roar.

There is an upside. I now know exactly where the motorcycle is when it comes to condition. That means you can jump on and head off into the boondocks with a pretty high degree of confidence.

One of the things I did from day one was fit the biggest capacity lithium battery you could squeeze in, along with a charging harness. Bikes in my fleet can easily end up sitting for a month or two, and it's nice to not have to root around under sidecovers with ageing and fragile mounts, looking for charging points.

In this case, the lovely CBX is running a very full instrument cluster, some of which are aftermarket. In addition to the fairly comprehensive deck from Honda we have two temp gauges – one for oil and the other for the head (reading off a spark plug mount). The latter two are run by the accessory electrical circuit, which means you need to be absolutely sure you turn off the ignition all the way. Otherwise you're greeted with a flat battery, possibly days or weeks later.

One of the other little tricks we discovered with this model is it runs two fuel taps. The main is a traditional item that shuts or opens the pipes, located on the lower left of the tank, while there is a second vacuum-operated tap under the tank. The latter is notoriously unreliable and we've bypassed it. However CBXs will leak fuel if the 'normal' tap is left on, so you have to be religious about its use.

After all that effort, what's it like to ride? Holy heck it's big. This thing dwarfs the Hayabusas in the shed. It's also heavy – teetering around 300 kilos fully wet according to the stats.

Firing it up is no issue, though it doesn't run so much as rasp – there's a hackle-raising sound which is a little like two angry triples, which you can put down to a combination of air-cooled straight six and the lack of balance pipe on the current 2 x 3-into-1 exhaust system. Compared to a current liquid-cooled multi, it sounds raw and potentially explosive.

Like any older air-cooled engine, it takes a while to get up to temp, so a long warm-up and then a gentle ride away works.

Once up to speed, it sounds angry and is silky smooth – a weird combination. Oh, and it's alarmingly quick. It might be just 98 horses, but that's enough to accelerate the thing at an appalling rate, pulling strongly off the bottom end and very enthusiastic in the midrange. Top end? It keeps making noise and power, by which time you've realised this is 1980-something and not 2020-something, so it's determined rather than stunning.

As for the transmission, this is a solid effort from Honda for the period. It's pretty slick and the clutch has a nice wide take-up band.

Pumped up to the right pressures, the air-assisted suspension works well – on the plush side and in this case with a fair amount of damping control.

Steering is slow, which I'm perfectly happy with on something this size. It still responds to the handlebars on entry and exit, and feels settled mid-corner.

Braking? Yeah, well, it's fine for the period and you need to remain aware of what you're saddled up with. This thing is heavy and, if you're about to fire it down a sports road, which it will happily do, it has limitations.

There are bikes in the broad modern classic sphere or era that are cheaper and more capable than the CBX – Kawasaki's excellent GPz900R A1 springs to mind. I ran one not so long ago and can recommend it.

As for the CBX, it's fun to jump on these monsters, particularly once they're sorted. They're big, fast and clumsy by current standards and hugely entertaining. Oh, and by the way, in this case the kangaroo-hide seat is still in place...

Know your CBX1000s

There are four variants – two naked:
CBX1000Z
CBX1000A

And two with fairing and Prolink rear end:
CBX1000-B
CBX1000-C

Launch prices

Launch brochure (UK)

Two of the above illustrations are taken from spectacularly huge and heavy hardbook The CBX Book vol II, by Ian Foster, 2014 (above). Sadly it's no longer available through the usual retail outlets, but you may come across it on the used market.

See the CBX1000 in our shed

Plus the CB750-Four

And the period road test of the CBX1000Z in Classic Two Wheels

Specifications
Honda 1981 CBX1000 Prolink

Good
Fast
Huge presence
Loads of engine character

Not so good
Big
Heavy

SPECS:

ENGINE: 
TYPE: air-cooled, four-valves-per-cylinder, inline six
CAPACITY: 1047cc 
BORE & STROKE: 64.5 x 53.4mm 
COMPRESSION RATIO: 9.3:1 
FUEL SYSTEM: 6 x 28mm Keihin carburetors

TRANSMISSION: 
TYPE: five-speed, constant-mesh,  
FINAL DRIVE: chain

CHASSIS & RUNNING GEAR: 
FRAME TYPE: steel tube, diamond pattern main section, with engine as stressed member
FRONT SUSPENSION: telescopic fork, air preload adjustment
REAR SUSPENSION: Prolink monoshock, air preload and 3-way rebound damping adjustment
FRONT BRAKE: 2 x 276mm ventilated discs with 2-piston calipers 
REAR BRAKE: 276mm ventilated disc with two-piston caliper

DIMENSIONS & CAPACITIES: 
WET/DRY WEIGHT: 277/308kg 
SEAT HEIGHT: 810mm 
WHEELBASE: 1535mm
FUEL CAPACITY: 22lt

TYRES:
FRONT: 100/90-19
REAR: 130/90-18

PERFORMANCE: 
POWER: 98hp (73kW) @ 9000rpm 
TORQUE: 84Nm @ 7500rpm

OTHER STUFF:
NEW PRICE: Au$5040 + ORC in 1981 (US$3300, GB£2600)
VALUE of a good example in 2024: circa Au$20,000 (US$13,100, GB£10,300)

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