I've owned a few of these and you're going to like it .

My Son recently picked up a 1983 XR100 that smoked badly and is racing it in Supermoto ~ he installed a bigger carby and we hand worked up larger mainet & etc.  , then he found & installed a 185 C.C. barrel and lapped the valves in , opened up and gutted the exhaust , it scoots very well indeed now ~

He has no problem out running the 450's on the same track =8-) .

Of course , my Son has mad Moto Riding skills I never had even in my dreams but still and all , it's a very good and sturdy little Motobike you have there .

Don't forget to get a magnetic oil drain plug as there's going to be ferrous abrasive dust EVERYWHERE inside this engine ! .