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Front Sprocket Question

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Hcb
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Front Sprocket Question

Post by Hcb on Mon 24 Jul 2017, 10:33 am

Hi! (Sorry for mi English)

Mi name is Hugo, and i have a green italian CB500 (year 96).

The bike has 125.000 km, it is the best bike I have ever had. The best mechanics, the best resistance, there is no doubt.

But for a long time, over 100,000 km, the vibrations in high revolutions are incredible, specifically, when the bike reaches 6000 onwards.

I am aware of the old age of the bike, and I forgive these weaknesses. But, certainly, on long motorway routes, my hands hurt and the vibrations become unbearable.

The question is.. If i mount a diferent sprocket, of 17 teeth(default is 15 or 16?).. Could i reach the 120 km/h ( 75 mph ) over 5000 RPM?

In this segment of RPM, the bike is smooth and the vibrations are "bearable".

Thanks for the help.
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ANDYC
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Re: Front Sprocket Question

Post by ANDYC on Mon 24 Jul 2017, 12:31 pm

Yes you could reach that speed but your acceleration will suffer. I guess you mean under 5k rpm.
It would probably be easier to look at why you're handlebars have such bad vibration.
Are the bar end weights in place?
You could try new soft grips,
Have the carbs been balanced recently?
Does it happen in every gear?
The possibilities of the cause seem endless.
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Hcb
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Re: Front Sprocket Question

Post by Hcb on Mon 24 Jul 2017, 1:12 pm

Hi Andy.

First, thank you very much for the quick response.

About the vibrations. Believe me, I've tried everything. The handlebar has a large weight scooter barends, which make the problem more bearable. The carburetors are calibrated, and the bike reaches high speed without problem.

The exhaust is original.

I understand that after 125,000 km the pistons have reached some clearance and the repair would be very costly.

So, I'll just try to make the bike vibrate as little as possible, somehow.

The best solution, and the most economical, is change the sprocket to 17 teeth. The bike will continue to vibrate, but I will not need to reach 6000 rpm in the usual way.

The question is, if changing the sprocket will involve any long-term damage.
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alanp
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Location : Norfolk, UK

Re: Front Sprocket Question

Post by alanp on Mon 24 Jul 2017, 3:32 pm

Welcome to the mystery of CB vibrations. Unfortunately some bikes seem to suffer more than others. 
From my own experience,  check exactly when your carburettors were last balanced. Honda specify every 8,000 miles. This could be several times a year for bikes in frequent use.
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ANDYC
the 900
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Re: Front Sprocket Question

Post by ANDYC on Mon 24 Jul 2017, 3:47 pm

I wouldn't worry too much about the mileage, as long as it has been looked after with regular quality oil changes it will last for ever Very Happy 
The engine that is!
Mine did over 423k kilometers.
I didn't have vibration problems but mine was the 'S' model which has rubber mounted handlebars.
Are yours the original handlebars?
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eternally_troubled
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Re: Front Sprocket Question

Post by eternally_troubled on Mon 24 Jul 2017, 3:52 pm

Hcb wrote:...
The question is, if changing the sprocket will involve any long-term damage.




No, you should be able to change the sprocket without causing any damage.

If your current chain and/or rear sprocket are particularly worn you might want to replace them at the same time as replacing the front sprocket...

Also, have you checked the exhuast mounting bolt for tightness?  I suspect that if this came undone/loose it might cause extra vibrations.


Last edited by eternally_troubled on Tue 25 Jul 2017, 7:24 pm; edited 1 time in total
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Hcb
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Re: Front Sprocket Question

Post by Hcb on Mon 24 Jul 2017, 6:15 pm

alanp wrote:Welcome to the mystery of CB vibrations. Unfortunately some bikes seem to suffer more than others. 
From my own experience,  check exactly when your carburettors were last balanced. Honda specify every 8,000 miles. This could be several times a year for bikes in frequent use.



Hi Alan.

Unfortunately, the times when my CB was soft as silk ended.

However, for me, even with these problems, after having bikes like, for example, a tdm 900, the CB500 seems to me the best bike built to date, and the fun it gives me has no comparison with other bikes I have used.

Browsing the internet, I read an article where it was said that the CB500 was the top one on a list of many motorcycles. He does many things, too well.
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trevor machine
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Re: Front Sprocket Question

Post by trevor machine on Sat 29 Jul 2017, 5:36 pm

alanp wrote:check exactly when your carburettors were last balanced. Honda specify every 8,000 miles.

Laughing

At least twice that in the case of my two. They are both a bit flat now though, to be honest. Will book them in for a sync in the next month hopefully.

Just to add though, despite the carbs probably benefitting from a balancing, I haven't noticed an increase in vibes on either bike.

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