1935 Ivory Calthorpe 500cc Sports

• Purchased as a 'basket case'
• Restored by the vendor
• Modelled on a Calthorpe raced in Austria

This motorcycle has been built as a replica of a Calthorpe raced in Austria. The machine was purchased as a dismantled 'basket case', with two crankcases that were not a matching numbered pair, although they did fit together. The 500cc cylinder and cylinder head did not fit the crankcases, so the original locations in the crankcase had to be plugged and new ones machined. The original cylinder was damaged at the bottom so the cylinder was bored out and a large liner fitted then rebored to standard size. A new high-compression piston was fitted and the engine totally rebuilt. The timing cover was not the right one for the engine so the vendor had to modify the way oil was supplied to the pump, using copper pipes - all worked out well.

While checking the gearbox a crack was found in the casing so a replacement case was obtained and the gearbox and clutch assembly rebuilt. A new rear chain was fitted. As a dynamo was not going to be needed the existing chain case was modified. An aluminium container has been fitted where the dynamo would have been, to house a battery for the horn.

A new replica Smiths speedometer was fitted and new handlebars made to match the originals and then chrome plated. Stainless steel clutch and brake end-levers and twist-grips have been modified to look like the original larger size. The frame and wheels had previously been powder coated and fitted with tyres. The vendor repaired the original fuel tank and sprayed the Ivory colour. Calthorpe transfers were applied. New aluminium mudguards were fitted and the Druid front forks totally refurbished with new parts, links and bushes. Straight-through exhausts were fitted and copper baffles incorporated to reduce noise. The restoration was completed in March 2024.

The vendor had hoped to take the '500' to the Isle of Man but due to health reasons this has not been possible. However, he did manage to ride the bike in a charity event and reports that it performed very well. (The Calthorpe has been used for raising money for local charities: Rowans Hospice, Hampshire Air Ambulance and Blood Bikes.) The vendor had hoped that one day the Calthorpe would be raced in classic events, but now realises this must be left to the new owner, should they so desire.
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