Do bikes run richer or leaner in winter? Every time I ask this question I get opposing answers. My dealer says they run richer in winter because the air is more compressed. I didn't agree. I always thought is was the opposite. Does anybody out there know for sure?
I have always had a problem with exhaust smell on my bike especially on decel. When I get off the bike my clothes actually smell of exhaust. I notice it more in winter than in summer when it's hot outside and I need the make adjustments to my race tuner. I'm thinking I'm running to rich. One other thing, I get better mileage in summer than in winter. mid 30's in winter, low 40's in summer.
That's what got me asking this question.

 

That is true the winter temps cause the bike to use more fuel. Think about how a choke works on a carb when the engine is cold when first started it wont run due to the lean A/F ratio so that is why you have to cut some of the airflow by activating the choke. The fuel injection cycles longer to compensate for this until the engine warms. The fuel the is used in the winter has additives that allow it to burn off cleaner and faster due to this inherent problem with a dense air fuel charge, but u still end up using more slightly more fuel due to this 'special' fuel, longer warm up times and thicker engine, trans and primary oil, the oil is harder to move when it is cold so you use more energy.

 

Yes, they run richer in the winter. Internal Combustion Engines require more fuel in colder temps. On fuel Injection Engines the ECM controls the amount of fuel going to the engine. On My carb'ed ShovelHead Bikes I used to compensate by changing the jetting for the winter and summer. Hope this help's.

 

Yep, I proved that on Sunday....I thought my Fuel Pak was acting up because the strong carbon/fuel odor coming from my pipes. Then I remembered that I had the same strong odors last winter. Going out again tomorrow, so I'll see if it's still running rich. Temps should be in the high 50's, so we shall see....