The engine that applies are a pair of JP Racing B5-T and a Nova Plus 21-7. The break-in is finished (or almost like the 21-7) and need to change the conrod of all two. My question is regarding the conrod type.... Plain R7 or R6 with hardcoated wrist pin?

The JP came with the R5 and the 21-7 came with the R7, but checked dimensions and the R5, R6 and R7 are the same. Only changes small details: R5 is the heavyest, R6 is lighter but comes without the upper bronze bushing (and I think that needs a hardcoated wrist pin - only available thru JP Racing) and the R7... seems to be almost light like the R6 but with upper bronze bushing.

Those are Off-Road engines, they buzz on my truggy...

Salvatori, Uriah, ... ?