XJRider.com

These bikes are very "cold-blooded", i.e. they run poorly until fully warmed up and they are set from the factory to be very lean running for emmissions. The "choke" is really a fuel enrichment circuit, so rather than restrict air to get a richer mixture (like a usual Choke) these bikes feed don't alter the air flow but meter more fuel when you pull on the knob. The "choke knob" that you pull should have detents that allow the pull knob to be held in a couple of positions for varying the amounts of additional fuel. As the bike warms up you slowly move to the next detent inward (reducing fuel) until it is fully in when warmed. Yes, it would have been better if Yamaha made a full variable choke mechanism to better control the revs between detents but that was not the case. Therefore, you first start with full choke. Let the bike rev to 3,000 rpm or so and slowly move the choke knob in as the revs start to climb much above this as it warms. Now you can either slowly let it warm up completely doing this, but that could take like 15 minutes or more before riding with no choke (not really practical or fuel efficient) or do as I and most everyone else and ride easily with some choke on and slowly push in the choke when revs get too high when at a stop. Since the bike is somewhat warm, I set the choke so that it will roughly would idle at 1000 rpm without throttle, but I will hold the throttle open slightly to keep it closer to 1500 rpm (normal warm idle) at stops. Then I give the bike more revs than you normally would initially and slipping the clutch more when pulling away to avoid killing the engine until it is fully warmed and the choke knob is in. It will take a couple or so miles to get fully warmed this way. What helps a lot is if you change the stock pilot jets (stamped 17.5) with larger (20) pilot jets. Greatly reduces this long warm up period and low end throttle response. Procedure is on "the wall" of this website. Additionally, your carbs may also be slightly out of adjustment too and this should be checked as well, i.e. carb synch and potential vacuum leaks.