santa clause is coming to town and he needs help
 

The wife and I decided to shake down the 3 new 125's this afternoon. One of them just quit as she was going up a hill. Refuses to restart.

I haven't completely torn into it, but I've swapped a carb, spark plug and coil so far. All the parts from the dead ATV work fine on the good one.

On the dead ATV, I have spark and fuel flow, i've verified spark stops when you pull the emergency disconnect button. So I think the electrics are working, I'm wondering if it could have gotten out of time somehow.

Please, any help would be appreciated. I'm in a bind.

-J

More than likely it's a bad CDI. Try swapping one with the other to rule that out.

Or try swapping the suspect cdi box on to a running atv.

yep. swapped the regulator and the CDI from the dead quad into a working one. Fired right up. Put the ones from the ones from the good quad into the dead quad and still won't start. The only thing I haven't swapped is the engine at this point right?

You might need to adjust the valves on the one not running. It's possible that the valves are set so tight that the valves are not fully seated which equals no compression. This is common on just about all the china bikes and atv's.

yea, tried that also just now. They were indeed tight. same behavior though. Strange though that it was running perfect then just died without any notice. I'm leaning magneto (even though i have spark, who knows if its in time), but I really don't want to tear into it that deep without talking to the dealer first.

This is a real bummer.
-J

is it possible to pull the magneto cover without taking the engine completely out on a 125?

Did you check compression?
Also Someone else on here had an issue with the pick up sensor being set to far away. It still had spark but was weak. May be something to look into.

One thing I don't have is a compression gauge. I can feel pretty good puffs of air out the pipe.

Coil partial grounding on paint

coil is all plastic and just hanging there at the moment. not touching anything.

Sounds like it does not ground by contact with the frame. Alot of the bikes, the coil is metal and grounds against the frame by mounting bolts, paint underlying can make for bad ground which will cause the weak spark.

Thanks for all your help guys. I really appreciate it. No luck yet, but hopefully I'll get it.
-J

swapped out the stator and pickup assembly from a good quad and still nothing.

Is the spark plug wet?