I have a 2005 Kazuma Meerkat 50cc ATV. I bought it used and my daughter has ridden it without issues several times. On our first ride this year, it bogs / hesitates when applying throttle, never did this last year. At idle and wide-open-throttle it runs flawlessly, just poor throttle response. It just can't build RPM from idle unless the throttle is applied slowly.....explain this to a 5 year old. It has good spark and the carb float bowl is always full. I have disassembled and ultra-sonically cleaned the carb twice, clean air filter, drained/cleaned fuel tank, adjusted the valves, new NGK plug, new oil, new CDI unit, new coil, and checked the stator (compared stator readings to our Kazuma Falcon 110). I took the timing mark cap off to check timing advance with a timing light. I observed the advance when applying throttle and noticed it does not advance like it should, probably because the CDI timing advance is dictated by engine RPM. I still think it's a carb issue...seems like it does not want to draft fuel even though the bowl is full. Any ideas?

 

Maybe - if it has different settings for the metering 'needle' mounted on the carb slide, raise it one notch. OR, vacuum leak check around the carb and intake with WD-40. ??????, Possibly, 'corrosion' in the grounding connections for the coil ??? Tough one - you've already covered most of the obvious ones. 'collapsed' fuel line or filter. blocked fuel tank vent. ????

In the end, you could always 'jack up the radiator cap, and replace everything under it, and reinstall the radiator cap' - OH DARN, it doesn't have a radiator !!!!

 

I already adjusted the needle/seat in the carb. No leaks or no infamous manifold crack. The coil has been replaced with a Honda coil with the same result. The fuel lines are new and tank / petcock have been checked as well. The tank vent is open as well. I even checked it with a third CDI box of my Falcon 110. I'm stumped on this one.

 

kazuma 04-05 meerkats had a problem with the left hand handlebar switch, causing running problems like you're describing, kazuma and redcat had a bulletin on this . quick and easy way to find out if this your problem is to remove the front plastic, top piece only. locate the 2 wire haress connector going to the left hand handlebar switch and unplug the one for the lights, you will still have the starter switch connected. i'd try this before going any futher.

 

I gave this a try, but no luck. Engine still has not off-idle throttle reponse, whether it's warm or cold. Still does it with or without the air filter too.

 

Is it physically possible to temporally swap in the Kazuma 110 carb???

 

Nope. The carbs are the same for the 50, 70, 90cc ATVs, but the 110 is physcially different. Good suggestion!....but I already tried this too....

We went riding today and I had my daughter slowly lean into the throttle to get going and explained that she couldn't stop unless she had to....a temporary solution to this problem.

I had ordered a new carb, but I received the wrong one. I still suspect a lazy mag-pickup in the stator assembly. Unfortunately I don't have an oscilloscope to test it right now.

I'll update if I nail down the source.

 

hai.wi

 

Just an update:
I replaced the stator/magneto and seem to have stronger spark. I also replaced the carburetor with a new one. The ATV still behaves the same way....engine bog and stall when the throttle is opened. It seems to be running very rich since each time I remove the plug, it's wet.

Good spark and plenty of fuel, perhaps too much fuel even after needle adjustment. I still see no timing advance when the throttle is applied.