niksfish wrote:

Andy wrote:The 150RR has a steel liner [that often masks the ports in areas], and old school porting, whereas the 150SP is an all alloy, nikasil plated barrel, with NSR250 style porting.

So, what do you mean by that? I tought the cylinder was the only thing with nikasil.

The 1500RR barrel is "old" (think early 80s) 2-stroke technology. It's an alloy barrel, with a pressed-in steel liner. It's handy in that it can be rebored easily in case of seizure, but is far from optimal for a number of reasons, one of which is the liner often masks areas of the exhaust and transfer ports, affecting efficiency and consequently power. The 150SP barrel is all alloy, with a very hard, electroplated "Nikasil" cylinder wall. The all-alloy barrel means thermal expansion is more predictable, and therefore controllable, allowing for tighter tolerances, because it and the piston will expand and contract at similar rates as operating temperature rises and falls.

The NSR150RR barrel has rather crude porting, but the 150SP has porting much more akin to the NSR250, complete with the RC Valve, developed by HRC, and effectively used by all HRC 2T race bikes all the way through to the end of Honda's involvement in 2-stroke world championship Grand Prix racing in both 500cc (NSR500 and NSR500V NX6) and 250cc (NSR250, RS250R NF5/NX5/NXA, and RS250RW NJBC).

Remember the NSR150SP speed record will be set in perfect conditions, with a perfectly prepared bike. It's very unlikely to get near that speed on the street, and also highly inadvisable anyway, as it leaves zero margin for any kind of safety manoeuvre... and it's illegal!
_________________
Andy.
NSR-WORLD.COM

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