Does Sporty need a 6th gear
#41
Baker makes a Sportster six speed they say is a true six speed overdrive transmission with a sixth speed ratio that lowers rpms by 477 at 70 mph but you may have to mortgage the farm to get one. Unless one has more money than sence I just couldn't justify it.
Last edited by motohaid; 08-25-2015 at 04:22 PM.
#42
#43
#44
Join Date: Aug 2014
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#45
Had to do a little search cause I know squat about big twins
Found this page that listed ratios of the big twins for the 5 and 6 speeds.
http://www.hotbikeweb.com/motorcycle...vetrain-basics
The 2 charts are towards the bottom of the page.
On the 5 speeds 5th gear had a 1:1 ratio with a final drive ratio (relationship of front to rear drive sprockets) of 3.37:1.
The second chart is a little hard to read, the numbers dont line up with the column headers but its easy enough to decipher. The 6 speed ratios are on the left, the screaming eagle tranny ratios on the right.
Notice the ratio of the new 6th gear? Yup, exactly the same as 5th used to be, 1:1. Now they did lower the final drive ratio to 2.79:1 by going to a 4 tooth smaller rear sprocket but 6th gear is the same as 5th used to be.
So, again I say, "usually" when another gear is added to the tranny the "extra" top gear is "usually" about the same as the old top gear.
Found this page that listed ratios of the big twins for the 5 and 6 speeds.
http://www.hotbikeweb.com/motorcycle...vetrain-basics
The 2 charts are towards the bottom of the page.
On the 5 speeds 5th gear had a 1:1 ratio with a final drive ratio (relationship of front to rear drive sprockets) of 3.37:1.
The second chart is a little hard to read, the numbers dont line up with the column headers but its easy enough to decipher. The 6 speed ratios are on the left, the screaming eagle tranny ratios on the right.
Notice the ratio of the new 6th gear? Yup, exactly the same as 5th used to be, 1:1. Now they did lower the final drive ratio to 2.79:1 by going to a 4 tooth smaller rear sprocket but 6th gear is the same as 5th used to be.
So, again I say, "usually" when another gear is added to the tranny the "extra" top gear is "usually" about the same as the old top gear.
#47
Join Date: Nov 2010
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Wow! It's been a few days since I looked at this thread. These charts may be useful-
Below is a vid of a little ride on the 883 with stock gearing. The video camera is mounted on mini-apes with 2.5" riser extensions. There is very little vibration, even at hours of riding at 80 mph (which is about 4600 RPM on the 883).
The Sporty engine likes to run in the 3500 to 5000 RPM range. It is not hurting it at all.
Below is a vid of a little ride on the 883 with stock gearing. The video camera is mounted on mini-apes with 2.5" riser extensions. There is very little vibration, even at hours of riding at 80 mph (which is about 4600 RPM on the 883).
The Sporty engine likes to run in the 3500 to 5000 RPM range. It is not hurting it at all.
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#48
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Technically it is an overdrive at that ratio. Anything over 1:1 is overdive. I think it was hinted at that an extra gear with a final drive of 1:1 would be an extra "middle gear. while going beyond 1:1 is overdrive. In my opinion, on Sportster, I don't see what the need would be for overdrive other than MPG gain and they are already at 45 MPG I'm thinking. For example, I have a stock 86 Mustang GT with a Five Speed. The 5th gear is an overdrive, If I were to race or street race (which is illegal and highly frowned upon) I would never get into 5th because there is no real performance other than highway cruising. The car "performs" better as a four speed IMO. So, getting back to Sportster, an overdrive IMO is a bad idea for performance sake. It may be a good idea if using the Sportster to tour interstate.
Last edited by Super Glidester; 08-26-2015 at 11:10 AM.
#49
Technically it is an overdrive at that ratio. Anything over 1:1 is overdive. I think it was hinted at that an extra gear with a final drive of 1:1 would be an extra "middle gear. while going beyond 1:1 is overdrive. In my opinion, on Sportster, I don't see what the need would be for overdrive other than MPG gain and they are already at 45 MPG I'm thinking. For example, I have a stock 86 Mustang GT with a Five Speed. The 5th gear is an overdrive, If I were to race or street race (which is illegal and highly frowned upon) I would never get into 5th because there is no real performance other than highway cruising. The car "performs" better as a four speed IMO. So, getting back to Sportster, an overdrive IMO is a bad idea for performance sake. It may be a good idea if using the Sportster to tour interstate.
#50
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The following chart of a near stock 883 shows (blue torque line) that the real power does not start coming on until 3500 RPM, and does not start dropping until after 5000 RPM. That is where the bike likes to run, where it produces the most power, and where it is running most efficiently.
The following chart is of a Twin Cam, looking at the blue torque line, you can see that the power comes on much earlier- 2500 RPM, and starts dropping much earlier- 3500 RPM.
Totally different animals.
The following chart is of a Twin Cam, looking at the blue torque line, you can see that the power comes on much earlier- 2500 RPM, and starts dropping much earlier- 3500 RPM.
Totally different animals.