Pekingduc,

with temps in the 50-60 range (air temp), you should be okay on a stock NSR250 Radiator. There were times on cold days (40's) where I would add a strip of tape to my 21 (and 28 ) just to get a little heat going quicker, and allow me to remove it if needed.

The RS has such a narrow operating temp, as well as a rather large radiator, you need to run tape most of the time. There has been a couple very hot days (as in 104 or so) where I could get away without any, but even in the 90's I have at least one full strip on my radiator.

If you compare the NSR and the RS rad, you will notice the RS is basically two NSR's layered together. The cooling performance if the RS radiator is soo much greater then the NSR, without tape the coolant temp is kept way below operating temp on most normal days.
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Charles Gallant