It's no big issue Binka, simple a case of HRC knowing of a "trick" to make the lower cylinder more efficient and keeping things within the SP rules, and others with less knowhow following suit.

If the stock head is kept, the NSR is as reliable as the day is long - a hell of a lot more reliable that an old steel linered RD, that's for sure!

The use of the HRC head should be used in conjunction with 105 octane race fuel, HRC specifically state this, but running that fuel is beyone the practicality of most road riders. For this reason, the big Japanese tuners, and a few well informed individuals, have opted to use the 0.6mm HRC base gasket as a tiny safety margin against the possibility of detonation due to the fact that machining barrel and/or head surfaces was illegal in most race series, and again beyond the practicality of most road riders.

0.1mm is hardly going to shatter the performance figures and port statistics of an NSR motor, but it will most probably help prevent the destruction of a barrel.
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Andy.
NSR-WORLD.COM

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