www.boxertrix.com

I have a 2003 S, and have done about 1000 miles on since purchasing it (with 9000 on it). On picking it up from the dealer and on my trip through Spain, I have noticed a vroomm vroom sort of vibration/sensation (yes the noise we used to make as kids when riding our ficticious bikes). Its a vibration through the whole bike rather than a sound from a particular area. Its most noticeable at about 3000 rpm in 4th gear.... just driving along rather than gunning it or even on overun. Its frequency is about once, maybe twice a second. I cannot think of anything travelling at that speed. If youve ever driven a 4 x 4 with a load of mud in the tyres.. its that sensation as you throw off the mud rather unevenly... really strange... ANY IDEAS??

cheers Stuart

I've had 4S's - they've all done it.

Balancing the TB's very accurately solves it partially but you'll never completely get rid of it. Reckon it's a cyclic resonance tied to engine rpm frequency/transmission vibration.

Cheers Gromit..... simply knowing that it seems to be normal is a relief in itself.
I will try and balance the TB's as you suggest.

Thanks Stuart

Gromit wrote:I've had 4S's - they've all done it.

Reckon it's a cyclic resonance tied to engine rpm frequency/transmission vibration.

Do what John.....you been reading them dodgy mags again Grom?
Bailey.

It would be worth checking the rear pivot bearings for peace of mind. Jack up the back end, grab and wobble the rear wheel along horizontal and vertical planes. Any knocking will probably mean bearing replacement is needed. And check the gearbox and final diff oil levels; bike on wheels, oils on the edge of level plug threads.

mine is rough was rough as hell at about 4k which has got better with the miles although never gone completely away..

Ade

Just as Richard says,mine used to be a horror for it,but certainley doesn't do it now,Twin Max, fresh plugs, good fuel.

winger wrote:Just as Richard says,mine used to be a horror for it,but certainley doesn't do it now,Twin Max, fresh plugs, good fuel.

Mine is considerably better in the midrange with the PCIII, might even start better next week when I get around to bodging the power supply direct off the battery
Don't agree about the fuel tho - makes no odds to mine

Stuart
I've had this s for six years, well most of it anyway - and only just a couple of months ago, out of the blue, it started doing exactly what you've described, mad, what is that?. These are all weird bikes; you think it's just a motorbike but actually it's a barmy relative that's come to live in your garage....

If it's been in a dealer's and they have done any form of fettling on it, just make sure that he throttle cables are not trapped and are sitting properly in the cable guides near the throttle bodies.

Paul

I reckon it's down to a slightly out of balance rear meself - I went through a period of using Azaro 45s which have a really deep tread and they all made the bike do it for the first few 1000 miles then it settled down. I've not used them for a while now and haven't had the problem very often since

Just remembered an earlier bike (British - long time ago) I had; the new tyre was rubbing the mudguard and made that noise!!!!!

Thanks for all your comments and advice... I will action them asap. I tend to think it more to do with Gromit's suggestion.... It just feels like that. Although I should say that it is wierd, having had new tyres fitted, there are no balance weights at all. The tyre marks are by the valves.. but no weights.... can these wheels be in perfect balance?? Cheers Stuart

I've only ever been told once that a new rear was in perfect balance cos he checked it twice up at Micheldever - perhaps you've been lucky