1-My bike is currently at 36.000 km's. I get a funny feeling that front side of the bike wiggles especially on corners.

My repair guy said some time ago my handlebar bearings (you know, the ones look like a cubic needle) needs to change.

Is that the cause of the problem ? What kinds of problems will it make if i have a corrupted, broken handlebar bearings ?

PS: my wheel bearings are changed, air pressures are at normal (33,36), i can't think any other problems.

2- i'm gonna change my fork oil soon. I went with motul 10w medium last time. I wanna try 20w motul (heavy) oil. Does heavier fork oil tends to help GS500's cornering performance ?

I ask this because the most enjoyable thing for me to do on motorcycle is corners

Cheers!

Top nut on the stem torqued appropriately? Tires in good shape no abnormal wear? I find that shuddering while leaning is often a cupped or feathered front tire.

Grab a handful of front brake and rock the bike fore/aft and side/side.  If your head bearings are in need of service, you'll feel it knocking around.  Torque the nut and try again.  If it still feels loose or doesn't turn freely, bearing replacement is in order.

Hi Navy,

A few years ago I tried new seals and 20w fork oil. It helped a little bit but not much. I only weighed about 130lbs back then, with gear, but I was still unhappy with how soft the forks were.

Now that I'm up to 155lbs with gear, I swapped to better springs (the correct rate for my weight) and went back to 10w oil (as per the sonic springs recommendation). I'm very glad I did!

15w seems alright, a little stiffer at the front than old, slightly leaky, 10w.

Quote from: Cincykz on September 22, 2018, 12:58:56 PM
Top nut on the stem torqued appropriately? Tires in good shape no abnormal wear? I find that shuddering while leaning is often a cupped or feathered front tire.

Reinforcing the point from Cincykz ... how bad is you tire wear? more than 70%?


Little deformation on the tire profiles can cause head shaking....   I had this experience with many of my tires... however.. it happened on straits only..  low speed ...with the hands of the handles...

heavier fork oil should go in concert with stiffer springs.

Fork oil won't affect how stiff the suspension is, it will affect how quickly it can move, or more specifically, the resistance to fast movement. If you put too heavy oil with soft springs then you will just reduce small bump/fast compliance and due to slow rebound damping will likely cause the fork to "load up", or to be too slow to rebound (not enough force from the springs to overcome the rebound damper) and move the static position of the suspension lower after successive bumps.

With stock spring rate 10wt is probably best, maybe a mix of 10 and 15 wt if you ride mostly on very smooth roads. On my bike with 0.90kg/mm springs 15wt seems about right, but those springs are like 50% stiffer than stock. No wonder then that the fork oil has to be about 50% heavier than stock.