[benastro]

imported post

Been doing a bit of riding down under and have a hankering to get the revs down when at cruising speed (~90kph (56mph)).

I heard on this forum about the possibility to swap the final drive, but cant find the post again.....Google has not shown up anything helpfull.

The specs say my 82 Aspy has a final ratio of 3.1, the 84 and on has 2.833.

I dont know how to run the numbers to tell me how much it would drop the revs to even know if its worthwhile chasing.

I know it will impact on the take off, but thats fine, I ride like an old guy anyway. I would rather the peace and quite and improved fuel economy. (Planing a big trip, besides if its a straight swap, I could always swap it back after the trip?)

Can anyone shed some light on this idea?
Is it a straight swap? Do I have to change the wheel as well? Do the 3 bolts that hold it on the shaft arm match straight up?
All those questions and more.....

Thanks a bunch guys.

Ben

 

[philcsand]

imported post

you will see a 9% drop in revolutions. So at 4k, it'll drop to 3640 rpm. (If I did the math right...) I don't know if 360 RPM's is enough to make it worth your while, but if so, then soldier on.

My only experiment with chainging the gearing of a bike was on my KZ750... chaindrive, so I went up one size on the front sprocket. (12 to a 13, and a 42 rear sprocket...) It wreaked havok with everything, had to use a LOT of clutch to get moving, but it was nice at speed. The problem is that in Seattle, we have no speed limits, because who needs a speed limit when cars don't go over 25 MPH during rush hour!!! (Stop and go was a nightmare.) Generally speaking, I think that the designers give a lot of thought to the gearing of these, and all bikes. To fiddle with it may get you a gain in one area, but almost definatly you'll loose out somewhere else.

 

[twisty]

imported post

astrotlv wrote:

Been doing a bit of riding down under and have a hankering to get the revs down when at cruising speed (~90kph (56mph)).

I heard on this forum about the possibility to swap the final drive, but cant find the post again.....Google has not shown up anything helpfull.

The specs say my 82 Aspy has a final ratio of 3.1, the 84 and on has 2.833.

I dont know how to run the numbers to tell me how much it would drop the revs to even know if its worthwhile chasing.

I know it will impact on the take off, but thats fine, I ride like an old guy anyway. I would rather the peace and quite and improved fuel economy. (Planing a big trip, besides if its a straight swap, I could always swap it back after the trip?)

Can anyone shed some light on this idea?
Is it a straight swap? Do I have to change the wheel as well? Do the 3 bolts that hold it on the shaft arm match straight up?
All those questions and more.....

Thanks a bunch guys.

Ben, as far as I know you can't use the 84 final drive in your 82, you can use the 81 &83 though..

You also can't baseyour overall gear ratio on the final drive numbers as the transprimary, trans secondary,& 5th gear must be figured in also. Multiply trans primary times trans secondary, then multiply that times the trans 5th gear ratio, then multiply that by the final drive ratio to get overall gear reduction in 5th gear.

Twisty