I purchased a Chinese 300cc ATV about a year ago (looks like red Honda clone), and I have had an ongoing problem that I cannot manage to figure out. Essentially the problem boils down to the fact that it will start and run just fine sitting in my Garage, but craps out with every trip to my deer lease...

My Deer lease is in Uvalde TX, and is mostly rocky "mountain" terrain... Elevation is around 1000ft. Home is DFW areal elevation around 800ft. I take it to the lease, and it starts and runs fine for a day or two, then will not start again, just cranks, fires once or twice, but will not remain running. Nothing I do at the lease gets it running again once this starts happening (including the same stuff I do at home).

At home I pull the plug, ground it, and crank to verify spark, and one time I found intermittent sparking, I pulled the coil and found the wire going from plug to coil was loose, got the wire tightened up into the coil and plug and everything worked fine until back to the lease and after 2 days (3 miles) it started doing it again, checked the coil at the lease and all was fine, never got it started.... Loaded it up and hauled it back to DFW, unloaded it, pulled plug checked spark, put plug back and cranked right up... I had done the same thing at the lease too and nothing.

Started it up off and on in the Garage for a few weeks and not one single issue. Took it to the lease and 3 days later and about 4 or 5 miles and then nothing....

I am running a different carb than what come stock with it, long story short, I had left fuel sitting in the carb for a couple months before the first time this started happening, and I thought I might have gummed up the carb, the original had a riveted bowl, so I took short cut and got a new one with as close as possible fit.

Engine is not flooding, every time I pull the plug its dry, no smells of gas. Gas is flowing to carb, Ive pulled hose and verified. Gas is in carb bowl, have verified this a few time when I was thinking it was a carb issue.

I have a new carb, cdi and ignition coil on order, and should be here later this week, I am thinking that I am going to replace all three. I have replace the fuel filter and plug, but I am going to replace them again as well. Is there anything else I should look into???

ATV is 1 year old, has 66.6 miles on it, always ran high octane as recommended. I always let it burn the fuel out of carb by turning off fuel flow and letting it run till it dies.

 

The cdi may be the culprit I would replace it and the coil and see if that sorts your problem.