Q: Hello guys. I own a 2012 Kawasaki ZX-10, which I think is still the best superbike money can buy. My bike is a black beast with an Akrapovic slip-on silencer/exhaust, and that’s the only thing I’ve changed.

I use the bike daily to go to work and I’ve never attended any form of track day because they just don’t appeal to me. Instead, I go out every Sunday morning on exciting high-speed breakfast runs with my friends.

But when I get past 260kmh my bike seems to be very nervous and a bit twitchy, especially when the road becomes a little bumpy.

So, do you know how I could cure this or make the bike more stable? I do understand that this is basically a ‘race bike’ for the road and that’s how it’s set up, but any advice will be gratefully accepted.

James Baggally

A: As you said your ZX-10 is primarily designed for the racetrack, so it might be a little unstable at high speeds on the road. It’s not as apparent on a circuit because the surface is much smoother than a public road will ever be.

Firstly, check your back tyre to see if it has worn ‘flat’ in the middle, which happens with continuous road use, that will make the bike weave at high speeds. You could also turn up the steering damper to a stiffer setting, if you haven’t already? And perhaps back off around 2mm from the rear shock spring pre-load, which will make the bike sit slightly lower at the rear and make the bike more stable at high speeds.

I don’t know how big or heavy you are but try to sit further back in the seat at high speeds, because sometimes that alone can make a big improvement with high speed stability?

Q: My bike is a 2010 Yamaha R1. I use it on the road and attend the occasional track day or two. But I’m not a ‘super fast’ guy because I’ve just moved up from the ‘C’ group into the ‘B’ group.

What I would like to know is, should I change the gearing on my bike for the track or just leave it alone? I’ve heard good and bad points for both sides of the question. I know you build BMW race bikes so I thought I’d ask you first. Some people said I’d find it ‘easier’ on the track using stock gearing because I’m not that quick to appreciate the sprocket changes, what do you guys say?

And if I went to Kyalami for example, what gearing changes would you suggest?

Thanks for your time…

Allan Freightman

A: If I were you I’d leave the gearing alone (standard), and just go out and enjoy yourself. Changing the gearing could make you go faster, but things will become more hectic as you up the pace.

But at our altitude (1,450m from sea level), you could drop the gearing by one tooth on the front to compensate for the loss in power (around 17% due to ‘thinner’ air). Many people do this for road use anyway, and if you do, your bike still won’t pull to the redline in top gear so don’t worry about that.

As for Kyalami, I’d drop two teeth on the front sprocket to get close to the ideal gearing for that particular circuit. I believe the stock front sprocket on your R1 is 17-teeth, so fit a 15-tooth version if you want to go that way?

Q: I’ve been riding my 2005 Honda Fireblade for over four years now with no problems what so ever. I have it serviced at the correct intervals and my Honda dealer has stamped my book to prove it.

But the other day I went out for a long ride and the bike suddenly started to emit a strange, but noticeable, vibration. It seems to be throughout the entire rev-range but a little worse just off idle. I’ve been all over the bike with spanners and screwdrivers but everything seems to be tight and fine. I also had the wheels balanced, again, just to see if that is the problem, but it is not.

So with you being an expert, well so it seems because I enjoy reading this technical section, do you have any idea on what this problem could be and should I be concerned? Can you please respond ASAP because my bike is my only form of transport?

Adrian Hardie    Jo’burg.

A: If the vibration is as bad as you say it is and it wasn’t there before I would stop riding your bike immediately until you discover the problem, or you might do irreparable and highly expensive damage.

However, it’s hard to say what the problem is without having the bike in front of me but we have seen clutch baskets breaking off ‘fingers’  on this particular model. They seem to do it for no reason but it would certainly relate to your problem, because the basket is now in a state of unbalance.

So if I were you I’d take off, or get someone to do it for you, the clutch cover and have a poke around inside. If the basket is cracked or damaged you’ll have to replace it because it cannot be fixed. If a new one is too expensive try the ‘Bike Hospital’, seeing as you live in Jo’burg. Or you can give us a call at Bikeworx (011 792 5795) and we’ll see if we can help.

Q: Hi there. I would just like to run something by you guys because you seem to be quite knowledgeable with everything to do with engines.

I have a MV Agusta F4 (nothing wrong with my bike though) and the other day we got onto the subject of fuels/petrol. What petrol should I run in my bike, 93,95 or LRP (lead replacement)? What affect does the different octane rating have on my bike and have you ever ran bikes on the dyno to see if there is indeed any performance advantage?

I’ve also heard that our fuel in South Africa is of poor quality compared to other countries, have you heard of this as well? So MV’s recommendations might not be applicable down here in SA.

Can’t wait to hear your comments on this issue and keep up the good work with the site, it looks great.

Trevor Allen

A: To be honest I’m not really qualified to answer these questions because today’s fuel is such a complicated chemical and therefore needs a complicated scientist to answer this.

But I’ve had a probe around on the Net and if you go to www.aa.co.za there’s a whole page on this subject that’s very interesting to read. So go there right now?

However, we have run one of our older race bikes on the different octane fuels on the dyno, and there were absolutely no performance gains anywhere throughout the rev range. So that answers that question, for a normally aspirated engine, as far as I’m concerned. The only gains we did see were from the Sasol 102-octane race fuel, but even that only made a couple of horsepower here and there. But the engine did seem to ‘pick-up’ revs quicker.

And yes, I also believe and have heard that we have inferior garage fuel compared to other countries around the world, but what are you going to do about that, not use it?

So if I were you I’d just run your bike on either 93 or 95 because it makes no difference as far as I’m concerned. And to confuse you even more, how do you know if you’re actually getting 93 or 95 from the pump, you know what South Africa is like? But go to that site I’ve mentioned, it’ll answer your questions perfectly.