There are 2 basic types of lock and the only real difference is the length of the rectangular piece above the barrel. Club spares has supplies of the lock with the long rectangular piece only £5.00 including postage BUT with only one key.

Seat locks are often similar to the lock pictured with a key inserted. If you are unable to get a seat lock it is possible to easily modify both “basic” locks.

The extension piece on the seat lock is a piece of tube 1.5 cm long, 1.2 cm in diameter and with an internal diameter of 0.8cm. One end is filed out slightly to make a tight fit onto the brass barrel. It is either glued in place or better still drilled and pegged with the peg being filed off flush with the extension tube. If the photos reproduce well you can just see that JAWA have used the peg method.

The surplus rectangular section can again be hacksawed away and then filed down to reduce it from 2.2 cm to 1.6cm. So there we have another money saver and nobody will know how clever you were.

Note: your seat must be secure for an MOT pass. JAWA CZ locks are not very strong and soft enough to drill out so always secure your bike with the best chain you can afford.