Bike is a 2017 non ES model and resides in the Texas hill country area.
First time the bike didn't start was on a cold day, approximately 50 degrees F. Bike had almost 24k miles with receiving only oil and filter changes. I pushed the starter button a few times and heard it fire but wouldn't fire continuously. Afterwards, I opened the throttle wide open, WOT, and it immediately started and idled fine. I smelled a hint of fuel or richness. I didn't think much of this since this was the first time and bike was due for maintenance.
A few weeks ago at approximately 25k miles I checked the valves (all within spec), replaced spark plugs, along with air filter. Also, changed oil filter plus sync'd throttle bodies. Note: When doing the throttle bodies I opened left cylinder, white painted air screw, a quarter of a turn (was fully closed) and adjusted right air screw to achieve balance. All good.
Last week I took a trip to the Big Bend area and twice the bike wouldn't start in the morning and exhibited same conditions as before with a few fires and then starting with WOT. And, afterwards, a slight smell of fuel. Both mornings were cold, or at least cold for me, with temperatures in the 50's. Nighttime temperatures were colder.
Bike runs great and starts fine with warm engine and or temperatures. I used the Yamaha shop manual to do all the work along with checking for error codes; found none. Obviously, the fuel air mixture is rich when cold as each time a no start has occurred I smell fuel. Plus going WOT is allowing more air for the mixture. Personally, I can live this but the situation bugs me as the bike should start without throttle when cold. Also, to complicate matters further I don't think I'll have cold weather at home for several months to do further troubleshooting.
My question: What sensors are being used to determine air fuel mixture for startup? Bike runs fine the rest of the time so I don't suspect something like an O2 sensor. Instead, maybe a sensor such as the coolant temp sensor? My thoughts are to remove such sensor, put in frig or freezer, and take resistance readings at different temperatures. However, I don't really want to remove several sensors to do this little science experiment. Thoughts...
First time the bike didn't start was on a cold day, approximately 50 degrees F. Bike had almost 24k miles with receiving only oil and filter changes. I pushed the starter button a few times and heard it fire but wouldn't fire continuously. Afterwards, I opened the throttle wide open, WOT, and it immediately started and idled fine. I smelled a hint of fuel or richness. I didn't think much of this since this was the first time and bike was due for maintenance.
A few weeks ago at approximately 25k miles I checked the valves (all within spec), replaced spark plugs, along with air filter. Also, changed oil filter plus sync'd throttle bodies. Note: When doing the throttle bodies I opened left cylinder, white painted air screw, a quarter of a turn (was fully closed) and adjusted right air screw to achieve balance. All good.
Last week I took a trip to the Big Bend area and twice the bike wouldn't start in the morning and exhibited same conditions as before with a few fires and then starting with WOT. And, afterwards, a slight smell of fuel. Both mornings were cold, or at least cold for me, with temperatures in the 50's. Nighttime temperatures were colder.
Bike runs great and starts fine with warm engine and or temperatures. I used the Yamaha shop manual to do all the work along with checking for error codes; found none. Obviously, the fuel air mixture is rich when cold as each time a no start has occurred I smell fuel. Plus going WOT is allowing more air for the mixture. Personally, I can live this but the situation bugs me as the bike should start without throttle when cold. Also, to complicate matters further I don't think I'll have cold weather at home for several months to do further troubleshooting.
My question: What sensors are being used to determine air fuel mixture for startup? Bike runs fine the rest of the time so I don't suspect something like an O2 sensor. Instead, maybe a sensor such as the coolant temp sensor? My thoughts are to remove such sensor, put in frig or freezer, and take resistance readings at different temperatures. However, I don't really want to remove several sensors to do this little science experiment. Thoughts...