Hello everyone....
This has been a pet project of mine for the last few years, with many updates, changes and tweaks along the way. It's basically a '98 RS50 with a '93 TZR125R engine. Top fairing is an NSR50 race one from Japan with the cutouts added for the Derbi lights, and seat is Honda RS125. Weight is about 97kg without fuel... it's running a tuned 170 top end, with V Force reeds and 35mm TMX carb. Re-profiled head for tighter squish (but same volume), zeeltronic and my own spec pipe. It is very useable pulling from below 3000, with the main power between 7-10500rpm.
Chassis has a cartridge in the stock fork, offset steering bearing for more trail, preload ajusters, home made subframes etc.. budget pitbike shock (was still £120 ish) but with a custom spring and I tweaked the shims stack inside to suit the bike a bit better. Front caliper is a 4 pot Brembo..mega... custom rear sprocket etc etc...
The paint is cos it was built originally for my girlfriend Alison who insisted it be purple.. 
Anyway, I joined here as the motor is of course similar to the DT's and the plan for the winter is to fit a WR crank. The 170 top end will of course need corrective work, I'm hoping to keep the port timing sensible, and then cut the head to suit (there'll be some piston top out issues I spect), I might have to cut a custom made insert on the lathe.. I've built a few stroked RD350 engines, and a couple of stroked smaller ones too, so have a pretty good idea of what's needed.