John,
I have an '01 150XR6. Great motor. It is finnecky to start. I have to pump the bulb 6 times, choke it, turn it over hold the choke a second or two, then release the choke and then she starts. (Sounds harder then it really is, transparent to everyone but me) Find your system to get her started. After that, she runs great all day! I use the same system even when it is super cold, that does not seem to matter. She does enjoy eating the gas. I was also very careful to run the miantenance dose of QuickCleen in the gas every tank full.
Great motor, never a probem to me!!
Carlos