Of all the bikes I've had over the years ; CM 125, CM 250, GT 550, XJ 600, and now the 500 twin, yeah ok it's no GSXR blah blah blah, BUT! it's cheap to run, nice and light, dependable, starts first time every time, flickable ( yes flickable  ) and it's great on the back roads .
BUT, that front end man, blimey! Keeps you on your toes 
Now I ride my bike everyday of the year as I DON'T DO CARS!!!! Blasphemy!!!! Yuk 
So, could I put denser fork oil in there and would a different tyre solve the problem?
My mate has a set of Bonny springs he is dying to put in the forks, assuming they are the correct diameter and length.
Any thoughts?
Dave                                                                                                                                                                             

Hi Dave, i guess you've kept the bike for a while. So a fork oil change wouldn't hurt if its not been done for ages. Also depending on the bikes age a fork spring change would be an advantage. But before that check the basics, tyre age and pressures. Also if adjustable check the pre load on the springs, could be too much giving it a bouncy feeling. If in doubt reset to factory settings and start from there. Sorry if this is like teaching your gran to suck eggs, but i always find sometimes get the basics right and everything else comes into place ok. cheers Alan

If you're really that keen to upgrade the suspension, I'd talk to someone who knows, such as Maxton. They can make suggestions, based on your weight and riding style.   Chucking springs, from a completely different model at it, is just as likely to make things worse than better.   As above, getting everything back to as-new, could be the easiest way forward.                                                                                                                                                                             

Alan & Rob, many thanks for the advice.
The fork seals have both gone recently due to the infamous Cumbrian roads.
I'm really not keen on putting the Bonny springs in to be honest as that would as you say become problematic.
The Avon front tyre needs replacing soon, so I may replace it with a Metzler.
Alan, what's pre-load? 
I don't call it me little scooter for nothing 
She's a P reg 96 model and I've had her for 3 years now, and like I said, she's a superb little bike.
Time to get the Haynes manual out methinks.
Cheers guys.
Take care
Dave                                                                                                                                                                             

Hi dave. Pre-load is the amount the springs are compressed to as standard before any extra weight is added to the bike like rider. the more you pre-load the springs the less bouncy the ride will be. over do the pre load and the bike will shake itself to pieces. you may not have pre-load on your forks but even the most basic bikes have pre-load on the rear to compensate for luggage and pillion.   On the rear the pre-load is set on twin shock bikes by a 5 position cam using a G spanner. A lot of single shock bikes tend to have a knob on the side to adjust.   On higher spec bikes you will also have the ability to adjust the rebound as well which is in the form of an internal damper to stop the springs extending forks or shocks too fast after hitting a bump.   Hope this helps                                                                                                                                                                             

Even if the forks have no preload the will have a spacer inside like a hollow tube between the springs and the cap on each side. You could extend that tube this will change the preload but I would recommend just taking back to original with either new springs oil etc. I had a GPZ 500 s an it was a great bike, mine was new and I was only 11 stone at the time and the factory settings were good for me used to do around 600 miles every other weekend on a mix of Motorway and bendy A roads

Hi Bluesbiker, thanks for the input but I do know what pre-load is, I was just making a joke about the Gpz. But, you do make a valid point about the rear set up, and that is it is set very hard on the bike for a pillion rider and I only weight ten and a half stone, therefore pushing the weight of the bike forward, yes?
Mind you, the rear end sticks like glue to the road, and I do carry panniers on the back occasionally. This hard setting on the rear plus the spongey forks would contribute to the front end handling. I think a G spanner is in order.
Jonny, how did you find her on windy days on the motorway?

                                                                                                                                                                             

hi try putting some progresive springs in there and some new oil good strip down and clean cheack that the bushes havent worn down too as there may be a little movement front to back ( all though that should fail an MOT if they do ) even so i would check that they should be fine then for the 500  normal road use                                                                                                                                                                              

Avon will be the culprit. Try a bridgestone battlax or some other tyre in a sports touring profile and compound.   A fork strip and rebuild will help. Progressive suspension do slightly stiffer springs for the geeper for around £70.   A maxton revalve to suit you would be about £150 but it will make the most difference.   The geeper should have no handling issues at all apart from a slightly soft front and thats it.                                                                                                                                                                             

 while we are on the subject  my daytona 900 has a very bouncy front end both on compresion and rebound   but i dont know what the two dials do on the front forks any ideas ??  i think the outer one may be compresion and the inner one sloted screw may be rebound                                                                                                                                                                              

Yeah, fair play, she handles well on the whole and I'll certainly consider the Bridgestone tyre too, but £150 for the Maxton revalve ooph. 
I think I have enough to go on here and thank you gentlemen, and over to you WheelyNealy                                                                                                                                                                              

Thats usually the set up Neal. A triumph forum or local dealer can soon tell you the standard settings........                                                                                                                                                                             

By the way.
The Haynes manual states 10W20 fork oil for the Gpz.
Now there are plenty of 10W on ebay but dont state what type.
Any suggestions?                                                                                                                                                                             

I tend to use Rockoil as it's always been a good brand but any know brand will do as you are quite light for a bloke I'd stick to that weight of oil I've put thicker in my CB750 and it made a load of differance (mind you when I emptied it it was about half the volume it should have been oooppppsss   My GPZ500s was a brilliant little bike LC350 like power but the reliability of a four stroker :oD                                                                                                                                                                             

Cheers mate  appreciate it


Aye, she's a cracking little bike.

                                                                                                                                                                             

I would be tempted to use proper fork oil of good quality, one that doesn't foam, your local bike shop should have that in stock.  Does yours have the 16" or 17" front wheel?  The 16's are notorious for feeling wishy washy through the bends, that coupled with the bikes non adjustable front end and very soft damping on the front (well known problem).  You might find that the next grade up oil would be better.  They are also known for their side/cross wind instability despite their weight.  But they are a cracking little bike, one of my mates partner used to have one.  Yes you really need a decent tyre on the front and the manufacturers size too, that will make such a difference.

Have fun with it
                                                                                                                                                                             

I too used to have a GPZ 500S and was very happy with it until I tried out (and subsequently bought) a 900 Triumph Sprint which made it feel a bit slow. I never noticed any handling problems even though it had the 16" wheels. I was a bit lighter then than I am now. I agree with the suggestions about using a proprietary and heavier fork oil to improve the damping and progressive fork springs to replace the old standard ones. Progressive springs are not expensive and a pair improved my Bandit's ride a treat. Enjoy the GPZ. 

Hi guys.
Well I spent yesterday evening with my mate replacing the seals and oil. The oil was a Motul 10W medium grade anti-foaming off ebay for about £9.
The old oil had emulsified and the bushes and cir-clips were a right pain to remove and put back.
It was very damp this morning on the way to work so I took it easy on the back roads, but she did feel twitchy.
On the way back this evening it had dried up nicely and I opened her up a bit. I still feel as if I'm riding on rails half the time, so a new Battleaxe on the front and progressive forks are definitely in order.
DG, it's the 17" wheel and you describe her perfectly and she is a handful when in windy conditions.
But she's cheap to run and a great commuter.
I think what I'll probably do is buy another bike for long distance touring and playing on and use the Gpz for commuting to werk. The Triumph Sprint would be great, Cataraptor 

                                                                                                                                                                             

Dave, think you have the right idea there mate.    Maybe a larger capacity bike will be less strenuous both on you physically and mentally.  My race bike with full fairing leaps sideways when hit by a crosswind, caught me out a few times, luckily I was wearing brown leathers at the time                                                                                                                                                                               

Oh mate 
I do like my Kwaks and I had been thinking of getting an old Gpz 750 which fitted me like a glove or a 750 Zephyr.
I want a bike I can fix on the side of the road and not have to have a pannier full of specialist bike tools if you know what I mean.
Money is not exactly flowing either. I just want a solid basic bike, maybe even a Bandit.