dear it means u just replaced the sprockets ? they put a lot of pressure on ur tiny engine so it cannot rev o its optimum nd this will destroy your engine very quickly.. i request u to add a honda cd 100 carburettor because the 70 carb is 15-16mm and the engine intake is 22 mm,, so by adding a 100 carb u will ge a true 70cc now it is hardly 60cc ,,
and thee aree 3 types of cd 100 carbs 1 is having a 18mm at engne side diameter another 20mm another 22 mm ,, use 20mm one,, that will not only give a good pick but also a bit safety with the new sprockets load,, cauze most ppl do it,,, hope u like it,,and the carb costs 1200 PKR ,,janyaaan honda cd100,,