ANOTHER FLOP WHEN new but a real bargain on the used market. It was 15kg overweight in the mid-90s which meant it never matched the best sports bikes of the day, but it's still an extremely capable road and track bike with accurate steering, a stable chassis and an indecent amount of power.
Bizarrely it makes a great sports tourer. Many has-been sports bikes get bunged into this class even though their uncompromising riding positions makes them uncomfortable over long distances. Not the Ace. Even the
pillion accommodation's pretty respectable, although you'll need an aftermarket grab handle if you're going to use that awesome instant power. A healthy bike will make 130bhp - go head-to-head with a modern 600 in a straight line and the Ace will knock its chips out of its hands and take its bird home. For relaxed, medium to high velocity mile munching it's spot-on. Brakes should be excellent too, unless they're seized.
Design wise it's not a million miles from a FZR1000EXUP engine in a YZF750 frame - basically a parts bin special and a stop-gap until Yamaha launched the R1 in 1998. So the last Thunderaces were bought cheaply by people who didn't want the latest missile - and are the sorts who tended to look after their machines.
All the EXUP/big 90s Yamaha foibles apply and are worth checking if you're buying. Be aware the valves need clearances adjusting every 18,000 miles so and as there's 20 of 'em, so it's not quick or cheap. The EXUP valve mid-way down the exhaust should move smoothly as you rev the bike, not rattle or be seized solid. Front discs can warp, the clutch can give up the ghost with light to moderate abuse and some fasteners corrode at the first hint of winter.
Oil consumption can be as high as one litre per thousand miles - it's not a problem but it means checking and topping up almost every fuel stop. Carburettors mean a smooth power delivery and no need to lash out £300 on a Power Commander - but beware carb ice if ridden in wintry conditions. Headlights are pretty poor but uprated bulbs make a big difference - and most will have them by now.
Key ID: '98 and '99 bikes were blue/black only.
Walk away: from high-mile (35,000+) bikes - they need too much attention to stay sweet.