I've had this same problem since I got the sled a few years ago. Now that my wife drives the machine I'd like to try & fix it, any help would be nice.
On cold start up with choke the machine starts well. As it warms up with choke on 1/2 it starts to die so I flip the choke off. but the idle is really low. In order to get it going i have to play with the choke on and off for the first minute or so until it runs good. I turned the idle up a little so it idles good after a minute of running from cold start up but then when the engine is up to normal operating temp the idle is too high, any ideas?? thanks.
On cold start up with choke the machine starts well. As it warms up with choke on 1/2 it starts to die so I flip the choke off. but the idle is really low. In order to get it going i have to play with the choke on and off for the first minute or so until it runs good. I turned the idle up a little so it idles good after a minute of running from cold start up but then when the engine is up to normal operating temp the idle is too high, any ideas?? thanks.
Did you carefully clean the carb? The pilot circuit?
i think it is the nature of the piston port motors. must have had 12 540/400/340/300/250 yamys in the family over the years and with squeaky clean carbs, they all did this. dad and his brothers used to warm them up with a stick or peice of wire to hold the throttle open to warm the sleds up with the track off of the ground. many times out at camp at -40c. you ever try to pull a 540 over at -40? swear you are going to break the pullcord even on the high mile sleds.