Weight of 1929 550cc SV piston and pin?

[Graham.Goral]

Hi all,

I'm posting this on behalf of Steve Sullivan, a local club member, who would like to know the weight of an original piston (including gudgeon pin) for a 1929 550cc SV engine (86.4mm dia and lower crown height than a VB piston). Does anyone have this information please - or have a piston which they can weigh please?

He is getting bad vibration problems with a JP piston and so would like to try to match the original weight.

Thanks,
Graham

[adrie.degraaff]

I don't know about a 550 but a 500cc sidevalve piston (VA?) 83mm with small 21mm pin but without pistonrings is 510 gram.

If he weighs it the same way as my 500 VH balance than it's 192 grams, if the crank is still in the crankcase than it's working the same way upside down but the overweight-underweight is contra.

This is a better way becouse a previus owner could have used a differend conrod to the crank, 21mm to 25.4mm pin is giving a large differends.