You could have a good 2-stroke tuner lightly port the barrels; preferably someone who knows Hondas (particularly NSRs and the NF5 RS250R as the motors are so similar) and their power characteristics. If you have/can get hold of an MC18 barrel to see the main differences, then they will have something to work with. The exhaust ports, so consequently the RC Valve flaps too, are considerably narrower than the MC18 items, so while you can widen the windows slightly, I wouldn't go too mad, as you'll soon be bypassing the benefits of the powervalve if exhaust gasses can pass right by them! The transfer ports need some tweaking, but the crankcases require the crux of the work, and without this an otherwise relatively stock motor just isn't likely to make impressive numbers.

You could try adapting a set of R2J expansion chambers, but remember they are optimised for the more extreme port timing of the MC18, slightly (marginally) higher compression, 32mm carbs, and a the new PGM ECU. If it were me, I'd be speaking very nicely to Martin77 to see if he'd be interested in making some hydro-formed pipes, but again you'd need to be prepared to pay for the privilege, and he'd need the bike for a while to build them en situ... if he was actually up for it! (He spends most of his time making Yamaha pipes, and is never short of work.)

There is 60hp in the motor, but it's going to be a pig to extract. A stock MC16 in tip top condition making its advertised 45hp is lovely to tootle about on though, and surprisingly nippy. A 50hp motor with a little effort would be great. Mid 50s would kick anything else's 1987 arse (RG/TZR etc., so long as your tuner doesn't go mad on porting and kill all the bottom-end/mid-range!) The HRC TT-F3 just made everything else in 1987 look silly! It was, after all, effectively a 1986 Grand Prix bike in a very poor disguise!


Sito Pons onboard the 1986 factory NSR250, upon which the NSR250R was based!
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

Check us out on Facebook! Please "like" our page!