Buying, owning & tuning a GB500

Just as you might expect for a machine that was only ever in the UK as a grey import, obtaining one today may be the hardest part of the ownership equation. The good news is that the GB500 is well made and finished so it shouldn’t be beyond the wit of man to restore one. Encouragingly, owners’ groups and forums all seem to agree the bike is also reliable so serious show stopper issues are fairly unlikely. The key must-haves are things like the tank, seat and panels which are hard to source. Similarly clocks can be an issue to find along with stands and the unique 2-1 exhaust system. Perversely the characteristic flanged spoked wheels are in demand by XBR owners who want to give their bikes a retro look. The XBR’S wheels will fit the GB but look a little out of place. Providing a GB has its original hubs or a pair can be found, the authentic look can be returned to the bike with some aftermarket rims and spokes. A GB minus rims and hubs is probably best avoided. Likewise it pays to ensure that the OEM carburettor is present, complete and preferably in serviceable condition. Apparently the Keihin unit is unique to the GB500 and spares are not common. Engine-wise the bike borrows from several contemporary dirt bikes so keeping the motor alive shouldn’t be an issue. Big bore kits such as the White Brothers 601cc conversion were a popular upgrade back in the day but the current trend is to dump a tired GB engine and replace it with one from NX650 Dominator. With only minor tuning the engine can deliver 30% more power and 50% more torque; something the 60s rockers would have killed for!