Picked up a 2 year old used 70 cc Chinese ATV (not sure of the make) for my youngest one's B-Day. Original owner said it runs fine, but needed a new battery. When I bought it, we boosted the quad to get it running and it started up then died after giving no throttle. I took it home, put in a new battery, and the lights work and all, but when I push the starter button, nothing happens. The brake light actually goes out when I push the starter. However, when I hook it up to the booster pack, it'll fire right up, but only run with the throttle engaged slightly. As soon as I let off the throttle, it dies. I can't start it unless it's boosted even with the new battery? Boys B-day is only a few days away and I liked to get it up and running before then. Any help/advice is appreciated.
Thanks in advance.

 

i'm not sure what's up with the new battery, there must be a drain happening on the battery. have you load checked the battery or check the voltage yourself with a multimeter? as far as idling, you need to clean the carb. and jets. it won't idle due to plugged jets.........

 

I checked the new battery with a multimeter and it read around 12.6-12.8. I fully charged it prior to trying. I haven't had it load tested though.

 

Measure the voltage right on your battery terminals while you are attempting to crank the starter motor. I.E. while the solenoid is engaged and the brake light is out. What is the voltage?

The above test is essentially load testing the battery. It will tell whether the battery can maintain 12 volts while the starter is engaged and drawing heavy amounts of current. If the battery voltage collapses under the starter load then the battery is bad or discharged. This is because we already know that the starter isn't bad, and that the engine isn't frozen, because it starts up fine with the booster supply.

Important note when doing the above test: Measure the voltage right on the battery terminals (plus and minus). Don't measure the voltage on the connectors/lugs that connect to the battery terminals. It is possible that you have a bad connection that drops voltage when the starter is connected. We want to measure just the battery without any other confounding variables added in.

If the battery is holding up then measure the voltage at the starter motor. Place the red probe on the starter motor input post and the black lead at the starter motor case. Again do this while attempting to start the quad. What voltage do you see here? It should be 12 volts too, but I bet it is not since your starter doesn't turn.

These two measurements will tell us where to go next.

 

Finally got a chance to try out some of your suggestions.
The multimeter was reading 12.85 at the battery connection with the machine off.
As soon as I turned on the ignition switch, the voltage went down to about 7.25. Then when I held the brake lever down and pushed the starter button the multimeter only read around 0.20?
I never had a chance to test the starter because the kids got home from school and I had to quickly hide the quad back in the garage.
Now what?

 

Only cure is too sell it and buy a new brand name childs quad IMO.

 

i like my yamaha, i like my polaris, i like my honda. i also like my hibird. sure the hibird is chinese, but i got it running dang good. nothing wrong with it at all.......it's all what you want or can afford........

 

Your battery is flat dead.

So the question is why? Where did you get this new battery? What kind of charger are you using? What current are you charging this battery at?

Are all the battery cells topped off with water? Did you have to add acid to this battery when you bought it (because it was sold empty)?

If you jump the battery to your car the starter cranks over fine, right?

If you filled the new battery with acid correctly, and you charged it, it should work. If it doesn't, take it back and get a good battery.

Once you get a good battery installed then it is *really* important that you make sure the quad charging system is working, else you'll be back in the same boat very soon. To check the charging system start up the quad and run at a fast clip with the lights off. You should measure 13.5 to 14.5 volts on the battery.

If you're having engine problems and can't do the test above then keep the battery charged up with a charger designed for motorcycle batteries until you can test the charging system.

 

Some good news today (one day before the kids B-day party). Picked-up a new battery (again) and this time it did the trick. A full 13.02 volts on the multimeter. Kids going to be thrilled tomorrow. Thing runs like a top now. Not bad for $200 when all was said and done.
Thanks for all your help Edwards. Much appreciated.

 

I'm glad it worked out.

Don't forget to check your charging system to make sure it will keep the battery charged.

Plus your meter seems to always be reading a bit high. Is your meter's low battery indicator on? Sometimes really low battery voltage will cause a meter to read too high. Else just keep in mind that your meter is reading on the high side and compensate accordingly.