i just picked up an 89 trail boss when cold theres no start i could put space heater beside the atv for few minutes and it would start and 99% of the time run good but then sometimes would spit and sputter and back fire.took.checked it out today while it was still cold pulled the plug and no fire.took hair dryer to the coil for about 30 seconds and had good fire and atv started right up.should i just go ahead and replace coil or could something else be causing this?thanks ahead of time without these forums i would be lost

 

Check the cold compression it needs to be very least 100psi better if 120psi

 

even if the compression was low the plug would still be firing i would think

 

True but I would still check it.Most likly problem would be a CDI or Stator problem

 

also check for good connections and no corrsion.