08 Z750 highway wobbles

[Eds]

Hey All,

I am trying to see if there is a solution to my problem. I am about 6'1 and 120kg's, big bugger

Around town the bike is great, but I travel down the bruce and gateway in brisbane daily and around 90km onwards the front of the bike gets a bit of a wobble. I have tried dampeners and preload settings etc but I cant seem to get rid of it. It was suggest to me by a mechanic from the shop I bought it from that the suspension probably cant handle someone of my size (good to know now). I have been considering buying another bike but I really like this one except for the wobble on straight roads. Does anyone know if there is something I can change to get rid of the wobble? (came from a CBR600RR which cut through wind beautifully)

Cheers

[bonester]

If it still has the original Dunlops on it, I'd be looking there. Worst tyres I have ever ridden on.

[dilligaf]

wheels balanced?

[Eds]

Wheels are balanced (apparently) and yes, its the original tire. I just put a nail in the rear so I might replace both and the rear spring at the same time because its rather jumpy and get the shop to do a proper sag setup and keep trying.

[Strika]

Most bikes have the suspension set up to cater to a range of riders. However, that range is usually from about 60kgs to 90kgs. Anything outside of this and it is better to have the suspension modified to suit. You say that you weigh about 120kgs, which means you really are pushing the boundaries of the capabilities of the suspension. With standard springs, 120kgs of weight will pretty much ovecome any damping force which the suspension can generate. This in turn will cause a slight raising and lowering of the rear suspension, causing the steering head angle to be varying ever so slightly and most likely start to cause a little weave. For sure, old worn tyres won't help and may even fix the issue to some degree. However the simplest solution is to fit heavier springs and have the valving modified to suit. Then go out and carve up all those wankers on sports bikes in the hills!!!!!

[Jonno]

Maybe try looking at the rear suspension, there may lay the answer.

There is a suspension thread in the tech section.

[oldman]

I have a 2004 Z1000 and had the same problem and it was tire pressure. I had it too high. Anyway the suspension on the 2004 Z1000 was way to soft for my 225 pound frame so I had race tech springs and valves installed, (the rear spring on mine is ok), It made a distinct difference on the handling, much more responsive in the twisties and much more stable on the straights. Have a shot of Jim Beam and a brew and all will become clear. Good luck.

[drewboy]

i know someone who had a similar problem, turned out to be tyres. having a very worn rear without the right air pressure can cause it, also having different brands front to rear can cause it. I'd buy a new set, Bridgestone BT021's or Michelin Pilot Road 2's are good value, anything more expensive than those you're pretty safe on quality, and check your tyre pressures regularly like at least once a fortnight.

[ducati_paul]

My Ducati 749 used to get wicked head shakes when the front tyre was worn, I couldn't take my hands off the bars for even a second, put new tyres on and it was all sweet for another 6000k or so

[4th]

my zed has OEM dunlops on it, gone from great to meh to god awful within 2k, still debating danger or try and scrape it to the 6k service on them VS cost if ends up in me scraping along road

not sure what tyres to get as replacement for mainly commuting.

had pilot power originals my 250 and loved them got maybe 15k commuting, then put a bridge BT16 on rear and found it a bit coarse

seem to be chewing through tyres a lot quicker but to be expected with more powerful bike, any suggestions ...pilot pure vs pilot road 2?