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Hi All, 
I'm working on my 615cc head (61mm bore, +3mm oversize) and I'm trying to reconcile Wiseco's ring end gap instructions with Kawasaki's FSM. 
The FSM specs are 0.15-0.30mm for both the top and second compression rings, with a service limit of 0.6mm
Wiseco is recommending an end gap of 0.27mm for the top ring and 0.34mm for the 2nd ring.  That means Wiseco's recommendation is already at the edge or over what Kawasaki recommends. I'm not sure which way to go.  Maybe the engine will run hotter with the new pistons so the gap should indeed be larger? 
 

Follow Wiseco.  They know their pistons, and how they will behave under high stress loads.  

follow wiseco specs
 

The difference might, in part, be due to the material the rings and pistons are made of.  Personally, I'd follow the  manufacturer's specifications, be that Kawasaki specs for OEM pistons/rings or Wiseco specs for Wiseco piston/ rings.