heloo i have 70 cc airsal kit on chinesee scooter 2 stroke and mikuni vm16 carb and original exhaust, with the stock main jet bike goes arround 65 kph on a straight and run good. Beacuse it got colder here i put main jet 75 beacuse that was the smallest i buy, with original air filter scooter didnt move, then i take off the filter and scooter move from the start but then it just boog, i guess main jet is to big. Should i try with a sport filter , will this help ?
I have no idea what the size of your original main jet is, so cant comment on the 75 main jet. Usually you want to go up about 5 to 10% for a big bore kit. I would buy a selection of jets or a jet box if available for your carb, probably not much dearer than buying a sport/open filter, and do the job properly. from the sounds of it the 75 is way too big, you want to drop down to around 72 and try it, if still too big drop down to a 70 and try again... repeat until you find the jet that runs good. Running a jet a little too rich isnt as bad as running one thats too lean. personally im not a big fan of open filters, they make your bike much louder attracting the wrong kind of attention, and when it rains, which is often in this country they absorb the water and your bike conks out... never a good thing.
