1997 GL1500SE Bouncing or Stuttering? Rear shock or something else?

[RReTo]

Hi,

i have tried to read this and other forums but decided to make new post now because couldn't find answer.

So my problem is that when driving the bike on almost any speed on straight road (20-100km/h), it feels like it's bouncing. First i thought it is stuttering a little but it barely changes when i pull the clutch lever and let the bike roam freely, so it makes me think could it be left rear shock gone bad? Air shock keeps pressure so it should be fine?

Weird is that this is happening also on the parts of the road that seem to be in fine condition, if i see a little bump or pit on the road and drive over it i don't feel anything wrong. Problem seems to happen when driving on road that seems to be in good condition or at least then i notice it more.

Is there any sure way to test the left shock? I just replaced the new rear tire and wouldn't want to wear it fast.
When i did remove the rear tire i didn't notice any leaks in rear shock, but i don't know how old it is (i just bought the bike and rode it only about 100km)

i also just found out my steering head bearing might need replacing. At least when front brake is pressed and i push bike back and forth i hear a little clack noise, can this cause my problem? I don't feel anything weird on handlebar when driving on road and the front suspension have been serviced last year.

Can it be something fuel delivery related? Bike accelerates without problems if i pull the throttle, but i'm thinking all the possibilities now.

Or is there any other advise from where should i look?

Also if i need new rear shock, what you recommend to use, i live in Finland but feel free to recommend anything. I have checked that Hagon sells monoshock option for this bike?

[WingsandThings]

Tire out of balance, or maybe a broken belt in the tire?

Does the bounce or stutter change with the speed you are traveling at?

[offcenter]

Maybe the drive splines in the rear wheel are stripping out?

[RReTo]

The problem is not constant or repetitive. But it happens almost all the time riding.
Sometimes it feels like it's bouncing more than other times. That is why i'm thinkin could it be the shock. Speed doesn't seem to affect it.

Drive splines were in good condition when i did check them while tire was removed.

[the_big_h]

I very much doubt that it's the shock.
The shock is there to control bouncing, but it cannot cause bouncing.
If it continues when you pull in the clutch, then it must be wheel/tire (not engine) related.
If it is happening at lower speeds (<70 km/h) then it is not likely tire balance - tire balance tends to show up at higher speeds.
As mentioned before, a broken/shifted belt in the tire is a common cause, making the tire out-of-round.
Another more remote possibility is incorrectly seated bead. Check all around both sides of the tire where it meets the wheel, the tire needs to be seated evenly on the wheel.
A damaged wheel could be out-of-round or wobbly, you can check this by raising the tire in the air, and watching it while you spin it. Back tire can usually be easily done with bike on center stand. Front is a little more difficult, but you may be able to stand on the pegs and watch it while riding.

[Megreenusmc1969]

I had something similar, happened at any speed. Turned out to be the rear tire. Once that was replaced, issue was resolved. I thought it was something with the front, as that was where my wobble issue was, but was in the rear all along.

Good luck with getting it fixed, and be safe.

[offcenter]

How about this....
Failing universal joint in the drive shaft??
That could cause the vibration you are feeling.

[MikeB]

Try letting the air out of the right shock and see how it reacts. The right shock is more of a leveler than a shock. Inspect the left shock for oil leakage.

[RReTo]

I did check the u-joint today. It was in good condition also the driveshaft is in good condition. Going to clean and grease them tomorrow and put everything back.

I did check the rear tire with screwdriver in place and only found like 1mm difference in some spots when rotating the tire so shouldn't be out of round. Tires are driven only about 100km

I will try to drive it with 0kpa in right shock after installing everything back. There was not snyt signs of leaking in the left shock. But i do not know how old it is.

Also thought that i will ask local service shop to test drive it and tell what they would suggest.