New to quads and mechanics, but a quick study. Bought a used Jetmoto 90cc. Started and ran fine, but when we got it home wouldn't start. Regular bike/atv shop wouldn't look at it b/c it was Chinese. Took it to a lawmower shop. Said it was the spark plug. Bought new plug, started and ran fine, but once it was turned off it would not start again. Disgusted I left it for a couple of days, then removed plug, cleaned it, replaced it, filled tank with gas and it started up again. ATV sat for a couple of days, again it would not start. Cleaned the spark plug again and it started. Is this a spark plug issue or something else???

 

each time you removed the spark plug and cleaned it, what kind of condition was it in? black, brown, white, gold/yellow? what color was the end of it? when it runs, how long does it run in between starts? 10 mins? 1 hr? 2 hrs? what brand of spark plug are you using? does it idle smooth after you change plugs and gradually get worse? OR, does it idle/run/rev normally the entire time you are operating the quad? in other words, how does the quad perform while running in between starts?

 

The spark plug (NGK brand) is black when removed, even after only two starts. The first time it ran very rough, kept stalling (prior to a new spark plug). The second time it ran smooth, I started with the choke open and then moved it to half once it was warmed up and it ran fine. Since it has only been started and run 4 times it is hard to qualify (especially since as soon as I get it started my son wants to ride it). What kind of test should I perform to get a better feeling for this (warm up time, running time, number of starts, time between starts, etc)?

 

adjust your carburetor, it's running too rich.

 

If you have to run w/choke on, there is a problem. Clean the carb and then adjust if needed.