I assume you mean the battery is OK and its turning over, it just doesn't fire up?
If it turns over but doesn't start, the most likely cause is dampness in and around the coil and HT leads. Dry out the coil, lead and plug cap and spray with silicone grease to keep out any further moisture ingress.
I use
this on my V8 Land Rover distributor, coil and HT leads when trialling. The Rover V8 is notorious for HT issues in damp conditions and this spray works very well indeed at keeping out the wet. It also resists high temperatures, stands up well over time and doesn't need reapplying very often.
Never had such trouble on the Ten, but I'm sure it will work equally well.
BTW - Welcome aboard the good ship XT660.com!