Q: Good day to you sir. My girlfriend recently purchased a 2003 Honda CBR 600 RR and once we’d bought it we noticed that the rear tyre on the bike is a 190.

According to a friend, who’s apparently a ‘bike expert’, it’s very dangerous to ride the bike with that sized tyre fitted to the back wheel.

So should we rather change the tyre back to a 180 that it came out with or is it still safe to ride with the current 190 tyre?

Your feedback is highly appreciated.

Regards Jehan Uren

A: If your 190 tyre has a 55 profile then you should be fine with no adverse effects. But if the tyre has a 60 profile it could easily affect the steering geometry of the bike, as it will increase the rear ride height a little, which could make the front end a little bit nervous, especially when turning into a corner. Some people don’t care though as they just want the fat tyre image no matter how the bike handles. And thankfully that’s obviously not you.

But as a rule if you go ‘ten’ either side of the original 180 (170-190), you won’t have to worry, depending again on that sidewall profile. If you want piece of mind though, which can affect all important rider confidence, next time go back to the original 180 size. Is your ‘bike expert’ a leather-clad pessimist?

Q: Love your new technical section on the new site, so I thought I’d join in and throw you just a quick one.

I’ve just fitted a slip-on exhaust silencer to my Honda CBR 600 RR and I was wondering if I’ll have to retune the bike to keep it running properly, simple as that and thanks?

Clive Whitlow

A: The problem, or not, with all modern day superbikes is that they cannot have the fueling altered using the standard and ‘sealed’ ECU, and don’t let anyone tell you different.

The only way to set the fueling perfectly is by using a Power Commander or similar device that ‘piggy backs’ on the original Honda ECU unit. It will then have to be set up by a person who knows exactly what they’re doing with these types of devices and doesn’t just ‘guess and try that’, so be careful whom you take the bike to please. And it can cost you in excess of R5,000!

But to be honest, just fitting a replacement slip-on silencer doesn’t warrant the expense of fitting a Power Commander or the like, as the CBR 600 RR will run fine with no problems at all, besides more noise of course.

Q: Over the past four years I’ve lovingly restored a beautiful BSA A10 650, from the mid sixties I believe. And finally it’s completed and all ready to go.

But before I start and ride the bike I would like to ask you guys a question about oil.

What modern day oil could and should I use in my bike? I’ve been told to use mineral oils only and not synthetic, what do you think on this subject? I look forward to your reply and I’m enjoying the new site, keep it going.

Alan Collins   Cape town

A: I wouldn’t worry yourself too much Alan because any of the ‘modern’ 

oils will be fine for your bike. A good 20w50 is a good bet and any familiar make will do, like Motul, Castrol, Repsol, Ipone, Putoline and so on. There’ll be no problems if you decide to use fully synthetic either. It is the best oil money can buy, so throw some in and get riding, nice to hear of a BSA bike being restored too.

Q: I happen to own a 2005 Yamaha Fazer 1000. I use it every day and for breakfast runs over the weekend. The bike has 52,000km on the clock.

Recently it’s begun to shake its ‘head’ while slowing down, even worse when I take my hands of the handlebars. The front tyre is relatively new. So I don’t think that’s the problem either. I’ve been told that it could be the steering head bearings that might need replacing. So I placed the bike on its main stand, pushed down on the back end, and there seems to be no excessive play or tight spots. So could you please give me any further information regarding the reason why it would do this, and thanks for your time to read this question?

Martin Scholtz

A: If you’ve checked the steering head bearings and you’re happy that they’re OK and the front tyre isn’t excessively worn I’d check out the rear tyre.

If the tyre is worn flat in the middle then that will definitely be the problem because the bike doesn’t know which direction to take. If you’ve fitted an oversize tyre that would make matters even worse. I believe your bike should have a 180-section tyre on the rear.

If this doesn’t rectify your problem it might pay to think about fitting a steering damper.