scooter pops and bogs under WOT

[mcginnismark14@yahoo.]

I have a jonway zuma clone 150cc gy6. It had 145 miles on it. When I am going about 40mph and then twist the throttle all the way it starts accelerating then it makes a pop pop noise and slowly slows down, if i let off the throttle then twist it again it accelerates fine. Seems to be a intermittent problem, top speed was about 58 now 52 mph then it pops and slows down to 45moh/ It idles fines and starts great. I'm thinking its either carb related or a bad CDI? It wouldn't be valves cause its intermittent and idles fine right? HELP!:s

[techie610]

Might want to look into upsizing your carb jets.

[blueboy5000]

Sounds like 1 of to things:

Defective PAIR system (emissions air pump)

or under-jetted. You should run a MINIMUM of a #107 main jet. Most bikes come with a #103-to #105 jet stock, which is too small.

[mcginnismark14@yahoo.]

:shrug:well the dealer guy can't recreate the problem. During my 25 mile drive to the dealer it sputtered and bogged about 4 times when going around 40 mph and twisting the throttle on slight inclines, it slowed down to 35 where I pulled over and then took off again slowly where it didn't act up for almost 10 miles. Im talking to the manager tomorrow about having them trying a carb from an other scoot to try??? Otherwise I'm bring it home and figuring it out myself, figured if it has a warranty why bother but they are a bunch of idiots. Where should I start? I'm thinking of ordering a new carb with a jet kit and a cdi to throw in. The spark-plug appears a whitish brown?

[oldkid]

When I bought my 150cc it kinda did the same thing. I replaced the CDI with a new one from, http://www.partsforscooters.com
and also added an electric fuel pump and pressure regulater from Autozone and no more problem.
Good luck

[mcginnismark14@yahoo.]

:clap:I found the cdi box was loose hanging right on the motor and was really hot. So i replaced that thinking maybe that was cause the intermittent problem, and mounted it on the seat frame rail as far from the engine as possible to keep if from possibly frying, and found the wires connecting to the ignition coil were a little loose so I crimped them tighter and took the carb apart to check it and the main jet was a 108, does that sound healthy for a stock scooter ran primarily in 80-110 degree weather? I put everything back together and it seems to be running better then ever! It does an indicated 58mph but thats china speed. Does that sound normal for a 150cc with 240 miles on it

[techie610]

Sounds good. :)
What type of air intake are you running?

[mcginnismark14@yahoo.]

stock everything including pair emission stuff.

[techie610]

The EGR crap is a joke. I did away with mine on all my bikes.
Look at unrestricting your airflow.