How can I stop handle bar vibrations?

[byke95]

Hi,

I've recently converted my stock handle bars to Renthal Streetfighters (braced) on my Z750. If I'm honest it was for mostly cosmetic reasons i.e. I don't like the 'up and out there' standard mirrors and wanted to fit Motrax bar end mirrors, this would also allow me to reduce the 'sit up and beg' appearance.

Back to the point: I'm getting quite a bit of vibration down the left- hand side of the handle bar (at high revs) and I can't figure out why. Everything is tight and secure, this is the second Renthal conversion I've done and didn't have this problem before.

Anyone solved this problem before or can think of a solution? Why is it just the left-hand side, is the throttle body absorbing the vibrations on the right?

As mentioned, I did the conversion for cosmetic reasons so I am prepared to swap back to stock bars but would prefer to keep the Renthals on.

Many thanks,

Phil

[veeeffarr]

Hi mate,

This is what bar ends are for.

Toby

[byke95]

[veeeffarr]

Because your bike/bar ends was carefully set up at the factory when it was built.

[byke95]

Thanks again Toby.

I'm well aware that care and effort (within a budget) was taken in setting up the bike in stock form. Although I'm fairly sure no-one checked that the stock mirrors showed anything other then the rider's elbows..

What I'm trying to find out is if anyone has had this problem before (and solved it) or can suggest some ways of reducing the vibrations I'm experiencing, prior to resorting to sticking the stock handlebars back on.

On the plus side, I have found some Renthal bar ends on ebay for under £10 so I'll give them a go if all else fails.

[the grim reaper]

Before you do that, get the carbs balanced and check the engine mount bolts with a torque wrench. It's unlikely but one of these could be causing extra vibration.

Cheers

Grim
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[byke95]

[ZRX61]

Put a couple of handfuls of birdshot inside the bars.

[byke95]

[veeeffarr]

Lead pellets.

[byke95]

[nrml76]

If you have money to spare, you can try a bar snake. Google for it. It is self explanatory. I cant vouch for it's effectiveness, as I haven't tried it. If the vibrations come on only at a particular speed or rpm, it might be cheaper to change one of your sprockets to one with a different number of teeth, so that you hit cruising speed or traffic speed at a differnt rpm. It doesn't eliminate the vibration, but makes it less troublesome. Changing the number of teeth on a sprocket will have some effect on top speed, acceleration and fuel consumption.

[MikeH]

It'll be Bar Ends

It's a commen prob with the XJR crowd upgrading to Renthals and then they get vibes. Worse case can cause vibration "White Finger" wih prolonged use.
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[byke95]

[Kickstart]

Hi

Weights on the ends of the bars are there to slow down the vibration. Get rid of them and you get the vibration in style.

Probably best to put some weights on the end somehow. For example some chunky steel spacers between the bars and the mirrors.

All the best

Keith
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[MarJay]

Its a resonance thaing.

You need to change the resonant frequency of your renthals.

A good way to do that might be to add weight. If the added weight makes the bars change resonant frequency to that of the engine vibes, then you'll make it worse.

It is possible, therefore, that removing the bar end weights may improve the problem. It may not.

What you want is a bike with a uniplanar engine mounting system... Like the Buell
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[byke95]

Thanks for all the help, true gents!

I took both mirrors/bar ends off and went for a ride, vibs still there with no noticable change...annoying it only happens at around 70mph plus (tested on a private road of course)

Could the brace itself be a factor?

I'm going to have a look at getting hold of a bar snake, in addition to getting hold of some bar ends (although I'm pretty sure the Renthal ones are fairly light weight) which will allow me to use my Motrax bar end mirror still.

[stinkwheel]

You could also stick some rubber washers under the handlebar clamps if they are the bolt on type. Some bikes have the bars totally rubber mounted. I have one and you can move the bars a full inch backwards and forwards on the rubber blocks. A bit wierd but it goes round corners fine

Messing with the weights on the bar ends is favourite though. You could try wrapping some lead wire or something round the end of the bar to see what works. Even the weight of an extra nut can make the difference.
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[Zimbo]

I've heard of people injecting the bar full of silicone sealant too, which can help I believe, haven't tried it though.

[byke95]

[nrml76]