Beginners

[MadMikeParticipant @madmike]

Jimmy there is much to consider in tuning a two stroke and particularly a BSA Bantam. I don't know if you have a copy but "Tuning for Speed" by Phil Irving is highly recommended and still highly relevant. If you haven't got a copy I suggest that you get one. Study also the effects of altering transfer ports as well as inlet and exhaust ports. Remember that packking the crankcases and increasing the compression ratio by skimming the head or getting your hands on a Todd head, and an aluminium barrel are very effective. An aluminium barrel is also much easier to work on. Have you tried the Bantam Racing Club for advice? HTH.

[WindyParticipant @windy30762]

Tuning for speed was a bible for the fast lads even his cam and follower details are on my steamer a good read even if a bit dated.

Mines a bit dogeared now could with a new copy?

Paul

Edited By Windy on 26/01/2013 00:15:08

[JimmieSParticipant @jimmies]

Many thank to all the ‘readers’ for the guidance given. I have a copy of PI’s book somewhere. The advice on the Bantam Racing Club’s site is far beyond anything I would wish to do. The George Todd article recommends simply widening and raising the top of the inlet and exhaust ports by about 2mm for ‘fast’ road work or 4mm for racing which would be adequate for my simple needs.

Further tuning would require a ‘better’ con rod/big end assembly, better quality bearings, improved piston, larger carb then an expansion box exhaust system. And so it just goes on.

Rex Caunt does an alloy barrel unmachined casting for £235 but I could not justify the expense. And Todd or B175 central plug heads are upwards of £50.

Many thanks again

[thomas oliver 2Participant @thomasoliver2]

Tungsten carbide burrs with a 1/4in dia. shaft are readily available and not too dear. They are infinitely better than carborundum. I have done various similar jobs and TC. is definitely preferable on cast iron.. It would not be too difficult to fix up a tubular extension to create more reach. I find that Loctite is extremely useful to fix steel to steel, instead of brazing..

I have just checked Ebay and a set of 5 suitable burrs is available for about £18.00 which is a gift.. There are also long shank ball ended cutters available. TomOl

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