Model 50 piston

Hi Alan,

I have seen this type of barrel bored out to 75mm but the bigger you go the more chance of distortion. The model 50 piston is a difficult one to replace because of it's design. When Norton re-introduced the 50 in 1956 they reduced the conrod length to 6.5" centres from the pre-war engine's 7". The problem is they kept the barrel height the same as the ES2 which makes the pushrods and tubes all the same length, so they had to add the .75" to the top of the piston which makes it look top heavy and will make finding a substitute difficult. You could fit a 7" ES2 conrod and a model 40 Inter piston but you will need to slim down the little end and re-balance the flywheels. You could shorten the barrel but that would mean removing the whole top fin and you will have to reduce the length of the pushrods and tubes. If you can find something similar it is most likely youwill haveto modify the little end or conrod etc. so good luck with any of that ! Regards, Richard.

Greetings,

Have a look here

JP are custom made here in Adelaide and have a good reputation in the "Classic" scene (bikes and cars).

Rgds Steve

Have a word with Mike Pemberton, he knows exactly how far you can go with a Model 50 rebore. We had that discussion.

I have seen AJS pistons used, taking the capacity to 400cc.

Last time I kooked, RGM had new pistons for Model 50's. Not certain if they were for the later models though.

Hi Alan,

another consideration would be a cylinder sleeve (liner).

I see in my Wassell book (I am a dealer) that J&P pistons also do .060" oversize pistons:

PISTONS - NORTONJP Piston for Norton MOD 50 350cc (1956-63) +060Bore Size : 71.0mm +060 OversizeCompression Ratio : 7.3-1

All the best,

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