Vibration Reduction- 750 kit or rephase

[padgett]

Hey guys, testing the waters here....

So I built an XS chopper a while back and I'm going to be rebuilding it again with the intention of making it better for a wuss such as myself.

I've done the usuals as far as vibe reduction (solid riser bushings, adding rubber where possible, carb balancing/tuning,sprockets) but I really want to get this bike to the point where I can do some long hauls on it.

I think the obvious answer to my question is "BOTH", but I'm not sure I have that money. So if I had to choose one solely based on just reducing vibes, what would it be? A mikes kit and a rephase are about the same price. What would be my best bet?

I'm still a few months out from buying anything, so at this point im just gathering ideas.

Thanks!

 

[Max Midnight]

You won't get rid of the vibrations and what I suspect you want to achieve is to minimise those that annoy you?

To that end I wouldn't have though solid handlebar risers would be contusive to this.

Both your option will alter things. Assuming the pistons in the 750cc kit are a different weight from OE then it will alter the crankshaft balance factor. This in turn will affect the degree of vibrations and where they peak in the rev range.
Re-phasing will also change matters.
Which is more agreeable only you can decide and a ride of a machine that has had either of these mods would help.

Other (cheaper) options include changing the bars and/ or bar end weights, inserting Vibranators, bar snakes or filling the bars with silicon sealer or lead shot. In other words anything that alters the resonant frequency will make a difference.

You could also try different seat infill or footrest rubbers.

 

[XSLeo]

I did the 750 kit on my 75. I found it decreased the vibes a lot above 4000 rpms. below that they were about the same.
I haven't done a rephase but from what I understand it won't decrease the vibes but change the frequency.
I have found that proper sync of the carbs is very important. getting both cylinders to pull the same does about as much as anything.
Proper wheel balance comes a close second. This smooth's out the ride very well.
Vibes at the bars can be reduced with shorter bars, not so much in height but width. A shorter tube flexes less the a shorter tube. Bars made from tubing with thicker walls will help, bars with a larger diameter help. Anything the stiffens the bars can help. Adding something in the bars to add weight helps.
Leo

 

[fredintoon]

Hey guys, testing the waters here....
So I built an XS chopper a while back and I'm going to be rebuilding it again with the intention of making it better for a wuss such as myself.
I've done the usuals as far as vibe reduction (solid riser bushings, adding rubber where possible, carb balancing/tuning,sprockets) but I really want to get this bike to the point where I can do some long hauls on it. - - -

Hi padgett,
750 kit ups the power, re-phase reduces the vibration.
And as you say, you've already done the usual vibe reduction tricks although I don't see solid risers as working for that.
What's left for a wuss to do to add comfort to his ride for the long haul?
You're gonna hate this.
But you did ask.
Add rear suspension.

 

[NONclow]

Hey guys, testing the waters here....

So I built an XS chopper a while back and I'm going to be rebuilding it again with the intention of making it better for a wuss such as myself.

I've done the usuals as far as vibe reduction (solid riser bushings, adding rubber where possible(?), carb balancing/tuning,sprockets) but I really want to get this bike to the point where I can do some long hauls on it.

I think the obvious answer to my question is "BOTH", but I'm not sure I have that money. So if I had to choose one solely based on just (???) reducing vibes, what would it be? A mikes kit and a rephase are about the same price. What would be my best bet?

I'm still a few months out from buying anything, so at this point im just gathering ideas.

Thanks!

How did H*rley make their bikes vibe less? RUBBER isolation mounts!

Proper tuning and damping with a rubber medium will address most of your issues...I'm curious as to where you added rubber, and also to what extent; thickness, type of rubber, and torque specs for the fasteners "clamping them down".

...and like Fred said, rear suspension helps...

 

[padgett]

Yea....I realize i'm fighting an uphill battle here with a rigid xs650.

Admittedly there are some things I haven't tried yet, but i just got the urge to rip into the engine again.

 

[fredintoon]

I've been wondering this ever since 1986 when I first owned an XS650:-
They rubber-mounted everything else, why fer fuxsake didn't they rubber-mount the engine instead?
Eight of these little bastards would have done it:-
http://www.gmt-rubber.com/PDFs/Bushes.pdf