I've recently bought a 1990 CBR1000F. It's done 70,000 miles but the chassis is fine, it's all original and the motor is completely oil tight and pretty quiet. However, there's loads of vibration, tingling through the handlebars and tank, and getting worse with speed/revs. Pulling the clutch in at speed shows the chassis is smooth and free-rolling, so I don't suspect bearings or chains and sprockets. Rev it up in neutral/with the clutch in and the vibration is still there, perhaps indicating that it's not the gearbox.

Which leads me to the balance shaft. I've read elsewhere on here that you can adjust the balance shaft backlash to reduce vibration at the handlebars – loosen the locknut, turn the shaft back until resistance is felt, then back one increment and re-tighten the locknut. But mine never meets resistance, simple turning and turning and turning... which suggests the shaft has never been adjusted (because you can't adjust it) and is now so far out of balance it's causing vibration.

Faulty adjuster? Faulty spanner operator?

Any and all advice welcome, as I'm riding from central England to St Tropez in a few weeks!

 

If it never meets resistance then it is likely that the gear teeth have worn past their use by date.
The shaft is actually an eccentric cam which moves the gear on the balance shaft closer to the gear on the crank shaft which gives the adjustment in backlash. If your shaft keeps turning then the gear has worn so much that the cam can never press the two gear sets close enough together.
Having said all that I'm not sure if this alone would give you the kind of vibration you're describing. I've often wondered how the engine would run with out it there at all. I may try it one day.
If you can get a new balance shaft set (and you must fit the whole thing as a set) fitted then at least you've eliminated that from the possible causes. It's not a big job and can be accessed through the oil pan so you won't have to drop the engine. It may cost a few sheckles though. If you're going to do it yourself you could have it done in a few hours.
Hope that helps. Good luck with your ride. I was down near St T recently. It's looking nice.

 

I have played with the adjustment on this both ways too much, too little, the difference... not a great deal.

i would be checking everything else first
Wheel balance
Engine mount bolts, including the locking nut on the centre bolt
Exhaust mount bolts
tyres o.k.

If it's loads of vibration i think it is not the crank balance, 70k is not many on these bikes.

Aussie Johnno

 

Guys we should e happy

This post was done by Mike Harmitage from bike magazine! He talsk about us as expert in the firts of 3 articles regarding old master blasters, I Have the magazines back home!

This is the proof that we rock!

 

Is there any way you can scan a page or two, showing the articles. That would serve nicely as a rock trophy. Mind you, I'm not sure that there are many rockers here, plenty of incontinent dribblers though.

As a follow up to Mikes initial query, I dropped my oil pan yesterday to check my balance shaft as I thought it might be contributing to a noise I've had in my engine for about 15K miles and had at last found some time to do some some exploratory work. It turned out that there was nothing wrong with it at all. As far as I know it's the original balancer. I replaced the cush drive rubbers in it about 18K miles ago and they are still tight and doing their job properly.
I now have to search elsewhere for my mystery ticking noise. A cylinder head overhaul is next on the list, but then that may have to wait for another 10K or so.
Life is full of mysteries. They get solved sooner or later.

Now, to the scanner with you Dragon. Show us your publications!

 

Have to find a scanner first

 

Henery ....... for ever paying compliments as usual ...lol

But yah Carl I'd give Henry's left nut to see those scans too

 

Sprock you blasphemer. Wash your trollies out with soap right now!

Christmas is for givin'.
My nuts aint.
Besides, they're far too big to give away for something like this. World peace on the other hand...... well I might donate one, not both. They're still operational ya know...... just!

C'mon dragon. There's a scanner near you somewhere. Put your mags where your mouth is!