The Suzuki GP100 is the fastest 100cc machine on Britain's streets. Capable of 70mph if screamed in third, fourth and fifth, the little motorcycle can keep up with the majority of its bigger 125cc rivals. Riders will also delight in having the ability to burn off drivers of Reliant Robins at traffic lights, leaving them in a sea of noxious blue fumes.
The GP100 is popular with both commuters and boy racers. In fact, the main advantage for 17 year old speed merchants is the cost of insurance. There are two types of GP on the used market. The GP100U with drum front and rear brakes, spoked wheels and several economy touches like painted mudguards instead of chrome. While the GP100X/D features include disc front brake, cast wheels, lots of chrome and a more sporting image.
Depending on past owners the condition of the machine varies from reasonably reliable to bloody awful. Reliability was never the bike's strong point. Common. ailments include seizing engines, gearboxes with more neutrals than the SDP and quick rot electrics.
The engine is a two stroke, rotary disc single. Power output is 8.5hp at 8500rpm. Using every bit of power to reach 70mph for any length of time leaves engine life on the line; seizure is a distinct possibility and the big-ends are subject to rapid wear. It is possible to make the bike go faster. Fitting an expansion chamber is totally unnecessary as this only results in higher fuel consumption (70mpg) and a bloody noisy bike. New gearing (37 back and 17 front) lets the bike rev out in top, with 80mph on the clock. Changing the gearing in the other direction gives great pick up but wrecks the chain and sprockets in 3000 miles. With correct maintenance chain life is around 7000 miles.
The engine doesn't last too well however kindly it is treated. The autolube feed pipe has a nasty habit of detaching itself, resulting in intermittent lubrication and seizure at worst. Expect piston slap around 9000 miles and a marked drop in performance at 13000 miles when a rebore is required. The barrel can be rebored twice and good used barrels are snapped up quickly at breakers. A rebore and piston kit costs £25. The wet multi-plate clutch seems unaffected by high mileage but suffers from oil drag when cold and in traffic, accompanied by loud noises.
The five speed gearbox doesn't become imprecise with age, it's just imprecise. Most owners will admit that a false neutral exists between each gear, especially fourth to fifth when changing up. Clutchless changes result in grinding noises. Changing the oil every 2000 miles helps a little. The drum front brake is very effective but the disc looks prettier. Either pad or shoe lasts 9000 miles.
The bike handles best with a 2.5 front and 3.25 rear tyre. The front lasts for over 14000 miles and rear for less than half that. It's only worth buying cheapo tyres as the bike doesn't go fast enough to warrant the expensive stuff. The bulbs blow and the indicators should be thrown away as they only last for six months. The lenses, connectors and wires all rot away rapidly. a The bike needs constant care and attention. It needs nursing all the time.
On average 2 hours a week must be spent keeping the machine in tip top order. The GP responds well to rags and polish, but it needs a loving owner to keep it shining. With time and effort the tank achieves a mirror shine, whilst applications of Autosol makes the chrome and alloy gleam. In this condition the bike holds its value well, as there are loads of GPs on the market but most of them in a pretty poor state. a Go for bikes in standard state as the chances are that they have been treated gently. Buy a bike with a noisy expansion chamber and chewed 2 screws and cylinder head nuts and you'll buy a whole lot of trouble.
The GP handles pretty well but the short length of it does mean at high speeds on twisty lanes the back end jumps around a little. Handling is improved by flat bars which puts more weight over the front wheel, that stops it twitching over bumps. The GP is the fastest bike in its class. As most teenagers seem content to thrash the bike, wrecking the engine and gearbox, there are plenty of spares available. It's a nice bike to run around on, but the water-cooled 125s are more reliable and the ever popular MZs a lot cheaper.
Danny Carter