Quote Originally Posted by booi10 View Post
barnone .... yes mine is 45 T ,,,, so how do you which one to choose if our make of bike is not listed ?? I take it the engine a such are a copy of something ?? I don't think it would be worth swapping the engine for 250 you would be better changing the bike or up to least 450cc,, thanks very much for help you sound very knowlagable and its the first time I have used a forum .... so happy days
You should change out the rear sprocket if your first gear is used up when you cross an intersection. Maybe like the one I suggested off UK Ebay ASSUMING your rear wheel is the same as ours which it probably is.

Like axa said we think you need a JTR279.xx. xx is the number of teeth. For example JTR279.35 is a 35 tooth rear sprocket.

The DF250RTB engine is sort of a copy of the Honda CB125 engine and is called 167FMM.

I do think it would be worth swapping the engine out for a air cooled over head cam full 250cc engine that is a copy of the CB250 engine. Probably could gain about a 50% increase in HP. Should be an easy swap. Going to any thing else gets complicated.