Density altitude

[Nats nella]

I went from a 44 tooth rear sprocket to a 36 tooth rear sprocket now my engine RPM speed seems to have gone down then another day it seemed like it was up again I did some research on density altitude and it seems like when the air is thinner the bike runs at higher RPMs is there anyone that can explain this to me thanks

 

[mark20]

I went from a 44 tooth rear sprocket to a 36 tooth rear sprocket now my engine RPM speed seems to have gone down then another day it seemed like it was up again I did some research on density altitude and it seems like when the air is thinner the bike runs at higher RPMs is there anyone that can explain this to me thanks

well, you rpms should go down when cruising the same speed, since your geared up higher.
the reason your rpms went up is becuase the motor can push the load, and you inturn get a higher top speed.

your clutch could also be slipping.

 

[Nats nella]

well, you rpms should go down when cruising the same speed, since your geared up higher.
the reason your rpms went up is becuase the motor can push the load, and you inturn get a higher top speed.

your clutch could also be slipping.

I understand at the speed is going to go up at a lower RPM but what I don't understand is some days my top speed is 37 and some days depending on the weather it is 34 I live in a subtropical area so we have a lot of days with a lot of humidity my clutch and everything else is brand new

 

[mark20]

I understand at the speed is going to go up at a lower RPM but what I don't understand is some days my top speed is 37 and some days depending on the weather it is 34 I live in a subtropical area so we have a lot of days with a lot of humidity my clutch and everything else is brand new

Humidity plays a large part as well, if its cooler the air is more dense, and inturn lets more air in and results in more power and speed

 

[Nats nella]

Humidity plays a large part as well, if its cooler the air is more dense, and inturn lets more air in and results in more power and speed

Funny you just mentioned that Mark I was just reading a hot rod article that was saying the same thing I do appreciate you I guess with these engines they produce such little horsepower that it makes a big difference from one day to the next and the way the weather is

 

[Wrench]

Did you notice any difference in the wind? A slight head wind can slow ya down 3 mph and a slight tail wind can speed ya up 3 mph

 

[Nats nella]

Did you notice any difference in the wind? A slight head wind can slow ya down 3 mph and a slight tail wind can speed ya up 3 mph

yes I did notice the wind difference just today I went to Walmart with the Wind and went a lot faster than going home against the wind

 

[Skyliner70cc]

For every 1000 feet in altitude gain (whether actual or increase in density altitude due to temperature and humidity), you lose 3% in power. If you are an airplane or helicopter, you also lose equivalent lift from your fixed or rotating airfoil.

 

[Nats nella]

For every 1000 feet in altitude gain (whether actual or increase in density altitude due to temperature and humidity), you lose 3% in power. If you are an airplane or helicopter, you also lose equivalent lift from your fixed or rotating airfoil.

Sounds to me like you have experience flying I read that it is extremely important to know your altitude or density altitude when taking off in a plane I live in Southern Mississippi on the Gulf Coast so the altitude here is basically sea level so if my density altitude is 1300 feet that would be the same as me being an actual altitude of 1300 ft correct

 

[Skyliner70cc]

Density altitude is what the airplane in its entirety feels. For example, on a real hot day flying in Colorado my density altitude at an airport that is 7,000 feet ASL (above sea level ) may be around 9,000 feet. My aircraft's performance on departure would be that if taking off at a 9,000 foot ASL airport instead of a 7,000 ASL airport. For out little engines, small changes in temperature shouldn't affect things much but when I road in Colorado, my carb jetting would get super rich when riding from 6000 feet to 12,000 feet over a mountain pass on the Continental Divide. I alleviated that problem by running E85 on a rear tank that I would blend via adjusting petcocks to get a leaner mixture as I climbed in altitude and it worked fairly well.