(This Retrospective article was printed in the June 2007 issue of Rider.)
STORY and photography BY CLEMENT SALVADORI
This really was a superbly entertaining machine, tremendous fun to ride, but one which could not find its niche in the American motorcycling world.
All too common thinking was that street bikes needed a minimum of two cylinders, if not four, and while a big single was OK for the dirt, it was not considered worthy of the road.
How soon we forget! Thirty years before, the Brits were having a great time selling 500cc BSA Gold Stars and Velocette Venoms, although the American public was much more attuned to the 650cc vertical twins that proliferated. The thumper, the big single, was a sophisticate’s choice, a bike that the experienced rider could take through the twisties at a greater rate than the bigger twins.
In 1987 Soichiro Honda was still exhorting his minions to come up with new product, even though the motorcycle market had been stagnant for a while—especially in the United States. For all we know, this might have been Mr. Honda’s own notion, as he had a great respect for the once-great British motorcycle industry.
The GB500 was as much a styling exercise as anything else, made to look like a machine one might have seen on the Isle of Man during TT race week. The official name of the motorcycle was “Tourist Trophy,” spelled out with decals on both side covers. Which, by its very name, was a race open to all touring visitors, harking back to the early days of the TT. The gas tank, the solo saddle, the clip-on handlebars, even the faux-megaphone muffler—all served to give it a very English air.
Of course, there were notable differences between the venerable Brits and the new-fangled Honda. The biggest was in the cylinder head, where the Gold Star/Venoms were running two overhead valves operated by pushrods, while the GB had a chain-driven overhead camshaft that depressed the four valves in the Radial Four Valve Cylinder (RFVC) head, which also had a genuinely hemispherical combustion chamber. Since the valve stems were not parallel, this meant that Honda had to make complicated double-jointed rocker arms in order to operate each pair… which never gave a problem.
The Brits like cylinders with roughly equal dimensions, the Gold Star having an 85mm bore and 88mm stroke, the Venom a perfectly square 86/86, while the Honda ran a short-stroke, oversquare cylinder with a 92mm bore, 75mm stroke. Part of that was due to the fact that the GB’s engine was derived from the 1983 XR500, a dirt bike that enjoyed a bit of torque. The XR version ran a pair of 28mm carbs, whereas the GB500 had one big 42mm round-slide Keihin.
In terms of horsepower the Brits liked to claim upward of 40 ponies, depending on the state of tune. The Gold Star, for example, offered various exhaust systems, camshafts, carburetors and compression ratios, from a 6.5:1 compression ratio for the touring model, up to 13:1 for racing; a reliable street version of a sporty OHV 500 was probably putting out some 30 horsepower at 6,200-6,500 rpm. Thirty years later the GB500 measured on the dynamometer a reliable 33 horses at 7,000 rpm.
But don’t knock that. A lot of riders know it is more fun to go fast on a less powerful bike, and to embarrass the 100-horsepower 600s on a curvy road. The GB used straight-cut gears for the primary drive, a wet clutch, five gears in the transmission and chain final drive. The powertrain sat in a full cradle frame made of steel tubing, with a squared-off steel swingarm. The engine was of the dry-sump variety, as were the Brits’.
The suspension was not much more sophisticated than that found in 1959, with a pair of preload-adjustable Showa shocks, the modern equivalent of the old British Girlings, and a non-adjustable fork with hydraulic damping. In keeping with its nostalgic sense the GB ran spoked 18-inch wheels and tube-type tires, though the Brits were running 19-inch wheels back then. However, those new Bridgestones were generations better than the Dunlop K70s of yore; Dunlop makes great tires nowadays, but the rubber compounds back then were less than grippy, especially in the wet.
The most noticeable advantage of the GB was the disc brake on the front wheel, with a twin-piston caliper, as opposed to the single-leading-shoe drums on the Gold Star and Venom. The GB ran a drum on the back, which is more than adequate as most of the effective braking comes from the front.
The wheelbase of the GB, with 30 degrees of fork rake, was a tight 55.6 inches, ensuring its ability to get around corners fast. The Brits were even tighter, running at 54 inches. The GB, with four gallons of fuel in the tank, weighed in at 390 pounds, much the same as its predecessors.
However, the Honda weight included an electric starter; pull out the choke, turn on the ignition, push the button, and the engine was lit. Yes, there was a kickstarter on the GB, but that was more for poseur purposes than being anything practical, as it needed to be in alignment, if not with the stars then with the capacitor ignition, which occurred only once every few kicks. The old Brit bikes required an entire drill: Turn on the petcock, fiddle with the handlebar controls to retard the magneto, tickle the carb, pull in the compression release, get that piston just past top dead center, then rise way up and deliver a hefty whack to the kickstarter. If the gods were smiling on you, the engine might fire right away, but usually the drill had to be repeated a number of times. That button was a very good addition!
Despite the immense improvements in lubrication systems, a kind rider would let the GB’s engine warm for a minute, snick the lever into first gear and ride away. Dawdlers could keep the engine poking along at any rpm, but the sporters would keep the revs above 5,000. The GB was best ridden on curvy back roads, far away from any freeway. One thing that the GB did lack was an appropriate exhaust note. The old thumpers had a sharp bark when they were on the gas, but Honda was adhering to legal decibel levels. The Gold Stars were famous for their backing-off twitter, while the Venom enjoyed a notorious boom when running over 5,000 rpm.
The GB500 was a really exhilarating motorcycle to ride. Still is. Since its demise it has become “collectible,” and few come on the market. When they do, the price is high. Though not nearly as high as that of a Gold Star.
I love the gb500…brings me back to the days in the 60 when I rode a BSA Victor. It really wasnt a good street bike as the suspension geometry was set up for the dirt…got a bit wobbly over 65 mph. Not so with the GB which is smooth on the twisties and has no wobble over 70. Only problem is POWER! I purchased mine (a 1990) in 98′ and planned to install a White Brothers 600 kit, but alas I couldnt find one. I did get a supertrapp and added 4 teeth to the rear sprocket. I would love to find a NOS White Bros. kit, but have had no luck. Ive seen the 600 – 650 engine swaps. Problem for me is transmission ratios. Most 600 – 650s have dirt gearing where the GB has a close ratio unit which is perfect. All being said I would like to find someone who has a White Bros. kit (new or used) for sale at a reasonable price. Let me know if you have a line on one.
Now my second problem. My GB has very low mileage (1,100 miles) and I get grief when I talk about “molesting” a “as new” GB as they have really jumped in price…seen ones in same condition as mine going for $6-8,000. I even saw one on Ebay still in crate go for 10K plus….YOW…paid $2,300 off the floor.
I would appreciate comments or feedback on my issues.
I live in the UK, and although the Honda GB500 TT was never officially sold here I had managed to buy three superb low mileage examples over the last couple of years.
I am a big fan of these Beautiful machines, I believe they are a true collectable Classic and are a great investment.
Just a recently I sold one of them for £5500 to a collector who is located in Northern Ireland.
I currently have not one but two of these beautiful time machines. Originally I had bought a 1989 model with around 5k on the clock and rode it until it was approaching the 10k mark. I was so suffering so much angst over deciding whether or not I should ride it or just stare at it in my garage and ended up selling it. I recently was contacted by the owner asking if I’d like to have it back as it was just sitting in his garage languishing. So I now have it back with exactly the same mileage as when I sold it to him !! To counter my dilemma I decided to but a 1990 model seeing as they were only produced for two years and picked one up with only 1500 original miles on it – ahem..for a price… Now though it sems I have another dilemma – having one from each model year and in pristine condition – should I ride either one.!?? So I guess now I must find yet another GB that’s ratty just so I can customize it and ride the hell out of it.
As you can by now guess – I am totally besotted by the Honda GB 500.
I fell in love with these the first time I laid my eyes on it back in ’95 or so in CA and wanted one bad but couldn’t afford one at the time. Fast forward to 2014 I started to do a search and saw one 2 hrs. away from me in VA. Previous owner was a lady who’s husband says she just “stopped” riding one day after having been in the saddle for years. We suspected she must’ve gotten too close to an accident and fearing that she won’t see her kids anymore, decided to hang up riding. Been sitting in their garage for a year. After a bit of haggling, bought her and took her home on the back of my truck. I was getting lots of smiles and thumbs up from random folks everywhere. Had her cleaned up, re-jetted, changed the gearing (1 down 2 up I think, can’t remember lol), a custom Jack Batson exhaust, which to me is waay better sounding and performs much better than the supertrapp or wb. She also has a custom seat and bar end mirrors. She’s got lots of miles on her but that’s fine by me. She’s meant to be ridden and that’s exactly what I plan to keep doing.
I live in the UK and have a friend who owns a GB500 which I have ridden often. I like it so much that I now own a XBR500 which , essentially, is the same thing but without the bling and at a less inflated price, although I have to admit that I’m not enamoured of its Japanese styling.
I have owned Velos and a couple of camshaft Nortons – the brutishness of the Goldie has never appealed – but none of these machines match the XBR for “chuckability” and just sheer fun. I truly love it and may modify it to resemble a more conventional and less extreme looking machine. I certainly propose keeping it for a long time.
I have a question
When replacing head gasket of gb500
Do you have to replace the cylinder
Head bolts or reuse
If the bolts show no obvious sign of damage or stretch, use them again. New flange bolts are not easy to obtain and a set of six will cost over £30.
Being new to the Honda GB500, would it be a suitable size being 6′ , 185lbs?
Vance, – The only way to find out is try sitting on one or find someone kind and brave enough to let them ride theirs !! My friend was your size and he seemed to tower over it. I’m 5′ 10″ and 160 and although it seems a little small for me after riding one of my bigger bikes, I LOVE riding mine – such a smooth ride . ( Well it IS a Honda right..?? )