More throttle left,but no more mph By nate7504 (Read 410 times)

[nate7504]

So I took my scooter for a ride for the first time in months (wisconsin winter)and was slowly getting it up to top speed the speedo said 60 wich I know is closer to 55mph,now I have never opened the throttle this slowly to get to top speed but there was no traffic so I wanted to take a long time to get up to speed I cruised for a bit at this speed and figured it was about topped out,but then I pulled the throttle and it was only at 80% yet it would not go any faster,why is it not going faster even though there is more throttle left? Btw it was not slack in the cable I checked that,how do I make use of that extra room at the top end,I did notice my rpm slowly creep up on the digital tach,like 100 or so that's all,but I had no increase in mph,maybe if I had more room it would have gained more speed,not sure.it was really cold to like 20 degrees out would that account for in moving a little faster?

[Bashan]

Cold air has molecules that are moving slower than warm air therefore they are closer together and the air is denser. The denser air has more oxygen to burn so you get more bang for your buck. So your getting a little more energy out of the gas you're burning and you hit top end at a lower throttle. However, the carb is set for summer air and can't use the last bit of throttle. If you were going to continue to run in the colder air you'd have to rejet or adjust the A/F. The dramatic change in temperature from what you normally run is similar to a change in altitude except you changed the gas densities with temperature.