The NSR chassis is pretty good, but can start to show it's street intentions when things hot up.
Our old NRS250 (NSR chassis with NF5 motor) was pretty good but the engine and RS/F3 suspension combo tested the frame to it's limit.
The F3 frame is somewhat better. Bigger headstock and some bracing works well.
The RS chassis is, well, just better still.
I have a 300 test mule. Today it's running on an NF5 bottom end, modifed NF5 pipes, different manifolds and avgas 100LL. The ignition and RC valve timing is adjustable, and it fires through RS plugs and caps.
It's running VHM heads so testing fuels is quick and easy. For everyday use the 14.2cc works well. On the blue stuff I started at 13.8cc and now at 13.5cc. It'll rev to 12,500rpm and beyond. I'm at sea level here and it was probably 30+C today. Colder weather at this same altitude would require a bigger volume.
I'm running 2 degree more advance than on 96 unleaded pump gas.
Unfortnuately it's not all cookies and cream as at the end of some tests today I had some electrical problems...........isn't that what they all say?
Something to do with making an NF5 into a 300cc. Not just a bolt on.