My RCS Silverstone has GPA2 crankcases that are looking a little sad and I decided to use a mint pair of GPA1 (MX1) crankcases I have. But, the GPA1, and GPA5 set that I have appear to slightly different.
The GPA1 and 5 sets are flush across the main bearing faces but the Silverstone GPA2 cases are machined back approx. 1.5mm across that face leaving a raised boss for the main bearings. There is also a quarter circle machined out below the barrel studs. This would result in a lower primary compression although larger volume compared to the GPA1/5 but why was this done? It appears to be original unless someone knows otherwise.
Any thoughts?
Dogsbody
The GPA1 and 5 sets are flush across the main bearing faces but the Silverstone GPA2 cases are machined back approx. 1.5mm across that face leaving a raised boss for the main bearings. There is also a quarter circle machined out below the barrel studs. This would result in a lower primary compression although larger volume compared to the GPA1/5 but why was this done? It appears to be original unless someone knows otherwise.
Any thoughts?
Dogsbody
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