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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Crankshaft Balance Method
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<blockquote data-quote="LoneStar" data-source="post: 115470" data-attributes="member: 585"><p>The crankcases, miraculously, survived with very minor damage. </p><p></p><p>On the existing holes, I would need more of them - for which there is not much room. Filling them would have the opposite effect to what's needed. Martyn's idea of drilling the circumference near the crankpin might work, although I suspect it would take too much drilling to remove the necessary weight. Pretty much all area near the crankpin where a hole can be drilled, it already has been - see pic. I'm not sure if that's the factory treatment or if some holes were added later.</p><p></p><p>I don't know the balance factor on the old assembly, as pictured. The crank and rods were apparently redone decades before I acquired the bike, based on receipts I inherited - original Vincent rods, and an Alpha big end. The pistons were Omega cast 8:1. I can't check the previous factor now, as the crank is together again with new rods.</p><p></p><p>Carrillo rods are heavier than Vincent (660g vs. 620g with races), although the reciprocating weight is lower (187g vs. 226g). This seems to result in the need for extra weight opposite the pin. Coventry Spares tells me that when they have cranks balanced with Carrillo rods, they always need plugs to add weight across from the pin.</p></blockquote><p></p>
[QUOTE="LoneStar, post: 115470, member: 585"] The crankcases, miraculously, survived with very minor damage. On the existing holes, I would need more of them - for which there is not much room. Filling them would have the opposite effect to what's needed. Martyn's idea of drilling the circumference near the crankpin might work, although I suspect it would take too much drilling to remove the necessary weight. Pretty much all area near the crankpin where a hole can be drilled, it already has been - see pic. I'm not sure if that's the factory treatment or if some holes were added later. I don't know the balance factor on the old assembly, as pictured. The crank and rods were apparently redone decades before I acquired the bike, based on receipts I inherited - original Vincent rods, and an Alpha big end. The pistons were Omega cast 8:1. I can't check the previous factor now, as the crank is together again with new rods. Carrillo rods are heavier than Vincent (660g vs. 620g with races), although the reciprocating weight is lower (187g vs. 226g). This seems to result in the need for extra weight opposite the pin. Coventry Spares tells me that when they have cranks balanced with Carrillo rods, they always need plugs to add weight across from the pin. [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Crankshaft Balance Method
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