100cc BBK upgrade issues... Need Advice
 

Hi Guys!!, I am a new member, but I have been reading your forums for a while now, Thanks for all the pre-advice! LoL

Now on to my issue, I have a 80cc (47mm) Jonway Sunny Copy, and it was running fine.... Had it setup with a Stock Clutch, NCY Pully and 4.5g weights... Also I installed a 24mm Keihei Carb, and it ran great.... i could do 37-40mph up hills and 55mph on flats. I thought i had a bright idea and decided to upgrade to a 100cc kit....once i completed installing everything hooked up all the wires/carb vac/fuel lines i started it up with no problems, the ISSUE at hand is that when i go above 1/2 throttle the engine starts bogging and occasionaly has a crackling sound, the engine goes RRRRRrrrr(BOGGGGGG)RrrrRRrrrRRRR(BOGGGG) and so forth.... i Switched the carb back to the stock tiny POS and it ran ok but the bike wouldent exceed 35mph.... My theory is i am using the STOCK intake manifold and its not letting enough air/fuel into the cylinder im at a loss, and i am debating if i should quickly throw back on my 80cc setup.... I would love some advice Ty guys for your time

You need to change the jet in the carb when you upgrade. Others should be able to tell you what size to get. (I don't know)

a 24mm carb moves a ton of air you need a big jet, especially with a 50mm piston, i would change to a #100 jet, or back down to a 19mm keihin with a #95 jet, are you using the stock airbox or aftermarket filter?