Combines N6 Engine RPMs

Easiest way is to measure the diameter of the drive belt pulley, the R5_6, N5 and late N6 or updated N6 will all be the same diameter. The newer N6 and N5 had the American Bosch M100 pump and Bosch nozzles, they don't blow near the smoke either. And at full throttle the upgraded early N6 should be turning 200rpms slower than the owners manual says. Hope this helps!

Thanks John, this helps a lot.

The upgraded N6 will have a 12.37" dia sheave and a rated rpm of 2400, at full throttle(no load)it will run about 2600 rpm, the older style N6 (not updated) will run 2800+ rpms (no load). The 670I was used in the N5,later N6's and R5_6's. The 670HI(meaning counterbalanced crankshaft) was used in your machine and will need rod bolts and bearings every 1500 hrs unless it has been slowed down to the 2400 rated rpm. The 670I was a longer life engine with the same HP, but turning slower and not stressing the rods and bearings as much. Both are good engines, just the 670HI was rev'd too fast in the 7080,7580, and early N6 and failure occured in the rod bolts and bearings areas. Good luck!