If it's a genuine MC18 Rothmans SP then it is an R4J, and the easiest of all the NSR's to delimit.
Have a read through the ignition page of the Tuning section on the main site for info on the plug to pull on the harness.
Airbox needs a couple of 20mm holes in the lid, and that's it. should see you with 60hp on a good motor.
Always check the jetting after ANY modification!
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Andy.
NSR-WORLD.COM
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