PISTONS & COMPRESSION RATIO'S | |
There are a number of classic machines that are fitted with pistons that are increasingly more difficult to obtain. In such cases I can find a similar piston, sometimes from an automotive catalogue and modify it to fit. In some instances this is a good opportunity to raise the compression and enhance the performance without affecting reliability at the same time. | |
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A typical example is the Norton engine above. This has been fitted with a BSA B40 scramble piston giving a compression ratio of 10 to 1. A 16H side valve piston can be shortened and re-shaped to go as high as 9 to 1. | |
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Lightweight Aluminium Barrels for Long and Short Stroke Engines | |
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The plan was to initially produce three engine sizes. | |
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HERE IT IS, A 600cc ES2 Conversion.This 87mm piston and ally barrel will make your ES2 into a shortstroke 600cc engine. It is not a D.I.Y. bolt on kit because I need to re-balance the crank to the weight of the new piston and machine the rebate in the cylinder head to fit the new barrel. The machining leaves a squish band. Couple this with an almost flat piston crown and you get a full 600cc short stroke engine with higher compression ratio and better breathing. Your ES2 will then be capable of pulling a higher gear with 80 mph cruising.
Early indications are showing a weight reduction of 8lb.
This shot shows the flanged liner that is shrunk in at 490 degrees. After being allowed to cool down to room tempreture the bore is then machined to the required size. This is a short stroke barrel and can be bored to 84mm, 85mm or 86mm. The maximum size permissable using a larger sleeve is 90mm.
This again is the first barrel bored out to 84mm for the BSA B50 high compression piston. If the barrel is to be used with one of my oval squish band heads a flat crown piston must be used.
On this shot with the piston set a T.D.C. the height of the crown can clearly be seen and is a snug fit in a re-worked Norton cylinder head. The compression can be raised or lowered by the simple use of compression plates under the cylinder base. | |
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