100cc BBK upgrade issues... Need Advice

HawaiiGy6Moddr · 05-10-2014, 07:49 AM

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

Firehawk989 · 05-12-2014, 08:05 PM

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)

mmsscooters · 06-02-2014, 08:49 PM

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?

05-12-2014, 08:05 PM	#2
Firehawk989 Join Date: Mar 2013 Location: Vancouver, BC Posts: 198	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) __________________ 2005 Yamaha BWS (Zuma) "Garfield" TP Black Trophy 70cc, Giannelli Reverse Pipe, 5g Dr. Pulley Sliders, Delta Clutch with Yellow Springs and Yellow Contra, Malossi Torque Controller, Naraku R-Vent Bell, NCY Adjustable Secondary Sliding Sheave, CF Reeds, Kege Analog Tach, Dual Headlight Mod, N.A. Rear Fender Delete, OEM Short Windshield.
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