The likeliest immediate problem for me is going to be the gearing. I live in the bush and after a few km of dirt I am on open roads and freeways for 30 to 100 km. Safety says I need to be doing 100 km and keeping up with the flow.

Now this bike was sold to me as a 100 km.p.h bike and obviously isn't, 85 to 90 more like it but I have had other small engine bikes (250cc) that could do 100 km plus all day. I know 25% smaller makes a difference there especially as I am 15 stone plus gear but I am hoping to improve the top end a little. It has no problem pulling me and a girlfiend away so it has plenty power enough for when I am riding solo (99% of the time).

I have read that road tyres (it has nobblies of course) will make it even slower, if easier to ride. So ... any ideas on gearing the rear sprocket as far as possible. Makes, sizes etc.? And possible carbie changes. It has a jap 'walbro' as fitted.