swapping out 5th gear from 5spd for 6th gear from 6spd.?

I have been doing some research, and from what I gather, the 550 6spd tranny wont work in my 650 because of the kick start.
The next option for a higher top gear would be swapping in the top gear from the 550(6th) for the top gear in my 650 (5th) for a 1-2-3-4-6 setup. I have read in the archives that this could work. does anyone know for sure?
does anyone have the gear ratios for the 650? are they the same as the 750?
found this...
550
1st 2.57
2nd 1.78
3rd 1.38
4th 1.13
5th 0.96
6th 0.85

750
1st 2.33
2nd 1.63
3rd 1.27
4th 1.04
5th 0.88

does anyone have any info or ideas? thanks
Scott

how about just trying differant sprockets?it would be easier and cheaper to fine tune. goodluck,happy wrenching!

I will be playing with sprockets too, I just would like a wider range in the gears, because as you know, if I go for more top end with sprockets, I lose a bit of acceleration.

I don't think it would work, but I don't know for sure.
The 550 six speed gears are thinner (because there is more of them on the same shaft) and I don't think it would engage all the way. I know the sixth gear engages another gear on the opposite shaft, and if you change the number of teeth then you also change the diameter of the gear. So I'm kinda doubtful that it will work.
.85:1 vs .88:1, not a whole lot of difference there, maybe 200 rpm at 65 mph.

You could possibly use the whole six speed trans by removing the entire kickstart and using a 750 side cover.

Post edited by: steell, at: 2006/04/10 22:31

steell wrote:

I don't think it would work, but I don't know for sure.
The 550 six speed gears are thinner (because there is more of them on the same shaft) and I don't think it would engage all the way. I know the sixth gear engages another gear on the opposite shaft, and if you change the number of teeth then you also change the diameter of the gear. So I'm kinda doubtful that it will work.
.85:1 vs .88:1, not a whole lot of difference there, maybe 200 rpm at 65 mph.

You could possibly use the whole six speed trans by removing the entire kickstart and using a 750 side cover.<br><br>Post edited by: steell, at: 2006/04/10 22:31

I was wondering about the width of the gears, thought that maybe you might put a spacer on each side?
but the number of teeth rules it out though
I never thought about taking off the kick start, that might be something to look into, might get a whole 6spd after all.....

650 ratios
Primary reduction 2.550
Gear ratios = 1st 2.333, 2nd 1.632, 3rd 1.272, 4th 1.040, 5th 0.889
Final reduction 2.625

Post edited by: OKC_Kent, at: 2006/04/10 23:18