We have a Honda Foreman 400 that won't start if the weather's too hot. We live in Maine and today it was 87 degrees and it would not start. Tried putting in a new spark plug, didn't work. Tried towing it behind the truck and it would start, but wouldn't stay running. When we got home, it was cooler. My son tried it and it started right up. This has happened before in the heat. (Yes, it's in neutral and the gas is turned on!) What could be causing this? Thanks for any help.

 

I didn't know they made a foreman 400. Are you sure it's not a rancher?

 

Sounds like its too rich. How clean is the air filter? Has anyone changed the mixture screw setting? Next time, try removing the air box lid, and seeing if itll start... this will lean out the mixture, alot.
If the carb checks out ok, then see if it has spark, next time it wont start. Just bring a spare plug along, and then you wont have to remove the one in the motor, when its hot. Just pull the spark plug wire off, hook up the spare plug, then hold it against the motor, to ground it, and then crank the motor.

 

are you trying to start it with the choke? My new rancher manual says not to use the choke on very warm days, the engine will flood too easily. I almost never use the choke with mine, i can usually get it to pop off with just the start button and feathering the throttle.