Before we continue with our 100cc engine restoration, I would like to introduce a new feature to the readers of this column. Ancient & Modern will now contain race and event reports for the historic, vintage and classic karting clubs. Obviously, 2006 is going to be a busy year with events, races and demonstrations planned up and down the country from April through to November and organisers and club secretaries should simply submit details of their events or results for inclusion. Please telephone the helpline number with the information. We have already had the first round of the Retro Racer series that took place at East Kirkby on April 2nd. The winners were:
Class IV Vintage:
1 Steve Greaves Fastakart/Villiers
Class IV Historic:
1 Tony Keele Keele/Bultaco
Class IV Classic:
1 Bob Phair Deavinsons/Bultaco
Class I Classic:
1 Jeff Gray Barlotti/Parilla
The next Retro Racer round is at Stretton, Leicestershire on May 21st. Visit the Retro Racer website (Weblink 1) for full details. The biggest event of the year is always the Shenington Superprix that will include static displays, on track demonstrations, a kart jumble and a drivers’ reunion. The event takes place on the 16- 18th June and is one not to be missed. Visit the Historic and Classic Kart Club for Great Britain’s website (Weblink 2) for full details. The winner of the Ancient & Modern photo competition was G. Rosenegk who correctly identified the kart as a Please Kart as well as naming several of the west country drivers. Well done.
The CIK have produced an excellent leaflet on karting to celebrate the sport’s 50th birthday. A copy can be downloaded from www.cikfia.com
100cc Engine Restoration (Part 4)
The final job to do is to remove the main bearings and oil seals from the crankcases. A heat source will be required to expand the aluminium cases and allow the bearings to drop from their housings. Every engine builder has his or her own preferred method but the easiest thing to use is a domestic, electric hotplate. The job is made easier if you have some suitable metal weights made for you so that the bearings will drop from their housings via gravity, without the need for any external force. Once heated, set the cases aside to cool. We can now start to examine the components previously removed from the engine so brace yourselves.
Barrel and Piston
I would strongly advise you to take your barrel and piston to a specialist kart engine builder and request that they carry out the required measuring and corrective machining work for you. The tight tolerances involved require measuring and cutting equipment capable of producing results to less than 0.01mm. Your chosen engine builder should have no problems working to this type of accuracy. As an example, piston to bore clearance on an old 100cc rotary valve engine will usually be set in the region of 0.09 to 0.10mm and the entire bore life of an old 100cc engine will be in the region of 0.5mm before it is scrap! I hope this helps put things in perspective.
Crankshaft and Connecting Rod
Things don’t get much better with the crank and rod assembly. For reliable performance, the crankshaft must be assembled and trued to within 0.01mm. Only your trusted engine builder has the tools and expertise to part your crankshaft, fit a new rod and big end bearing and then reassemble and true the crank. The work on the barrel and crank assemblies won’t be cheap but a failure of the piston, crank or rod under racing conditions will usually result in a scrapped engine. Make your choice. Next month we will continue with inspection and replacement of the component parts and, hopefully, we can do some of the work ourselves and save some money.