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76-78 cb750 k piston difference between earlier pre 76

C prince

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Hello members.. I have a quick question.. after much perusing regarding 750k pistons.. I need to know if any year sohc K piston will work in the 1978 cb750 k... reason I ask, is that 77-78 pistons are very hard to come by and my options economically point me to the earlier reproduction offerings( pre 1977) ...is the only penalty is a slight comp. ratio difference? ( background , engine is currently going back to original bore 61mm from previous owners disastrous attempt at an 836 big bore - head/ engine and new OEM bore cylinder is/are circa. 1978k) much thanks!
 
Yes, a slight drop in compression. The 77-78k; 75-76f have about 1/4” flat border around the edge and then a slight dome. You should be ok with early k pistons. A good machinist could make up the difference in compression for you by decking the gasket edge for you.


 
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