Tried and tested powerplant. Tranny is all new and intends to blow the shift myths.

The Thunderbird makes do with the AVL reworked A350 cylinder head and block. First introduced in early 2000, this vertical single cylinder unit displaces 346cc. Though the internal organs retain the age-old pushrod overhead valve system, changes have been incorporated in the block which now is made of an all-aluminium alloy with a cast iron sleeve. The height of the cylinder head has been increased and to accommodate the engine in the same frame the sleeve has been pushed further inside the crankcase, altering its external appearance. The same 18bhp max power now comes at a lower 5500rpm. What this translates into is quicker acceleration compared to the standard Bullet with the same (70x90mm) bore and stroke configuration. The engine breathes through a Mikuni constant vacuum carburettor which is yet another first for Enfield. This not only aids combustion, improving initial pick-up but coupled with the CDI ignition completely eliminates cold start problems. An advantage of this type of carb is the smooth power delivery. Unlike the old Dell'orto carburettor that suffered from flat spots, the CV carb only deposits a charge into the combustion chamber when the engine calls for it.

One drawback of the AVL block has been the level of engine noise. The decibel count on this stroker has increased considerably and the mechanical racket in the case of the Thunderbird is louder than that emitted by its exhaust.

Which brings us to the second quirk. The exhaust note has been restrained to a large extent by employing a longer and slightly wider muffler in keeping with the new NVH regulations prescribed for engines over 250cc capacity. These regulations are strictly in tune with the European Commission's latest NVH regulations. Accordingly Enfield was left with the option of employing twin silencers or designing a large diameter pipe or increasing the length of the current silencer. When we visited the Tiruvottiyar plant in Chennai we were amazed to see the flights of fancy taking shape in some out and out weird silencer designs. There was a single pipe unit which somewhere along the way found itself divided into two, a ridiculously fat pipe nicknamed 'elephant foot' etc, but in the end the long pipe version won the vote. Complying with regulations has forced Enfield to bring about a change in the torque characteristics and 26.97Nm max torque now shoves through at a higher 3500rpm in part by advancing the ignition timing to 12o BTDC at 1000rpm to 22o BTDC at 2000rpm.

The five-speed gearbox engaged via a heel-toe shifter on the left side of the T'Bird will finally see itself on a production series. When we tested the Lightning 350 there were a few ignorable oddities. On the whole shifting through the cogs was a smooth affair in contrast to the older gearbox and there were not too many false neutrals. With the T'Bird Enfield has gone a step further in refining this box to perform better. Shifting into first is smooth and noiseless, it is simpler to find neutral and false neutrals I encountered only a couple of times in over 500km of riding.