Yamaha jog cs50 main jet issue

hi guys I've just bought a 70cc big bore kit for my Yamaha jog. I need to know what size main jet I need to upgrade to to get my carb running efficiently. I've been told 15-20% bigger than the standard one but I'm not sure what size my original one is. can anyone plz advise cheers in advance. Trev

 

I have just found out the size it's size 68

 

if the stock size is a 68 your looking at around a 78 - 80 main jet for a start but its best to start higher then work down so buying a set of jets is more ideal . you then install a large jet start bike and have a ride, if its a bag of bones start dropping down 2 jet sizes untill your happy with the feel, ie no bog at wide open and not hesitation when you rev from idle .

 

ok great thanks Tam. yeah I've bought a size 80 main jet I'm just waiting for a new stator to arrive so after I've installed that I should be good to go. I'll keep you posted