Help me create a final drive problem! - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 12 (permalink) Old 06-04-2015, 09:12 PM Thread Starter
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Help me create a final drive problem!

Sup. Ive got a 90's VN750 and it works fine. I would like to change the final drive ratio, but obviously that's not as easy as on a chain drive bike.

In a perfect world, someone would chime in "oh, the 1500s use the same housing with a much higher ratio. Just swap one of those in!" But lord, this world aint perfect. Lets see what kinda damage we can do here.
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post #2 of 12 (permalink) Old 06-04-2015, 09:50 PM
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Cubic dollars and a CNC machine, have at it! lol

The problem may be, by the time the ratio is as high as you want, the bike will have no giddyup at all in any gear.

The money may be better spent making 5th gear a lot higher. Of course by that time, you probably could have bought another bike.

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post #3 of 12 (permalink) Old 06-05-2015, 07:16 AM
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x2 on that one many guys in here have scratched more than just there heads on this one and it all ends up the same way it would just cost too much and probly take away all your acceleration

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post #4 of 12 (permalink) Old 06-05-2015, 09:54 AM
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Why do you need to change the final drive for?these bikes like to rev

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post #5 of 12 (permalink) Old 06-05-2015, 10:50 AM
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leave well enough alone

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post #6 of 12 (permalink) Old 06-05-2015, 10:57 AM
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As someone who has put almost 180,000 miles on these bikes, I think the final drive ratrio is perfect. It will accelerate hard up a steep hill in 5th gear, and still cruise at 80 mph all day long at well below redline in 5th gear. These bikes do like to rev, which is unusual for a cruiser. They are faster in the quarter mile than many v-twins twice their size. There is more Ducati in these bikes than Harley. My Royal Enfield Bullet 500 is a slow revving single cylinder bike. with a top cruising speed of about 60. It has a seriously undersquare long stroke motor that would tear itself apart if you try to run it at much above 5000 rpm. Tons of torque, very little hp. The Vulcan is exactly the opposite. It will pull away from some sportbikes for several hundred feet from a dead stop.

I like both, but you can't have that with one bike. That's why I have both the Vulcan and the Royal Enfield, a low revving thumper that just rumbles down the road at low rpm, with lots of low frequency vibration and a nice thump-thump-thump sound from the exhaust.

I am a motorcyclist, NOT a biker.

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post #7 of 12 (permalink) Old 06-05-2015, 06:03 PM
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Originally Posted by centurynick View Post
leave well enough alone
There it is. If it ain't broke, don't fix it.

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post #8 of 12 (permalink) Old 06-06-2015, 03:17 PM Thread Starter
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Originally Posted by OleDirtyDoc View Post
Why do you need to change the final drive for?these bikes like to rev
I'm trying to build it into a salt flat bike and I need to do 250mph+
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post #9 of 12 (permalink) Old 06-06-2015, 04:43 PM
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hmm, massaging the 750 to make enough horsepower to go 250+.. I think that's gonna be tough one.

I may be wrong here, but the frame geometry is probably all wrong for speeds that high.

while I applaud you ambition, this is gonna be a long hard project.


if your gonna go with a streamliner type class, then you could always extend the frame and swing arm, and put another 'transmission' in between the front bevel and the rear to give you plenty of overdrive options

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post #10 of 12 (permalink) Old 06-06-2015, 04:54 PM
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convert the angle drive to straight shaft

if allowed by rules, convert to chain drive. Take less machine work and unlimited gear ratio choices.
Are you planning on turbo or blower?

If I remember correctly, bevel gears waste a lot of horsepower and vn750s use 2 of them. Lots of gear drag

As an alternative, check the final drive ration on other brand bikes, I suspect the Gold Wings have a taller ratio. Perhaps swapping rear ends might be easier.

I'm assuming you are not planning on running 250 in a stock class, which brings the question of what class you are looking at.

Last edited by thomasjf; 06-06-2015 at 05:06 PM.
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