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Too Bouncy!!

  • Thread starter Thread starter propflux01
  • Start date Start date
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propflux01

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Just got Suzi (my 83 GS1100GK) back up and running after replacing the front tire, replacing steering bearings, and replacing fork oil. After many searches on fork oil level (the fork oil removed was little and uneven-levelled) on forks with progressive springs, I set the level to 140mm (5.5Inches) with forks compressed, springs out. Got her all back together and took her out, and even with my hefty 210 lbs, the front end bounced around like a basketball, and turning was almost a scary experience! The tire is a CS Hi-Max, with 32PSI in it. Bike has always felt Cadillac-smooth before, now is way too bouncy. Any suggestions on what I may have done wrong? I have correctly torqued steering stem bolts, fork tube bolts, axle bolts, and axle retaining bolts. Levelled the forks in the tubes, etc. Just too bouncy!
 
Did you put in PVC spacers to achieve the correct sag? I put Progressive springs in my GK forks a few years ago, and it rides GREAT! I put Progressive shocks in the back at the same time, too.
 
You're running the same setup as me... when you say "too bouncy" can you clarify?
Do you feel the springs are too stiff? (I'm 165lb & don't feel the progressives are too stiff on my 1000)
What size spacer did you use? Is the spacer & spring combined approx level with the top of the fork tubes?
Are the springs rebounding too quickly? (in which case a thicker oil would help), what did you use? 15w? Thicker oil would give you more damping & means they would return a little slower.

A lower oil volume would make it a little softer too. (as the air above the oil has more room so won't compress like a secondary spring - I run 140mm with 15w oil on both my bikes).

Dan :)
 
Yes, the springs have been in there for some time. Only change is the fork oil, I have never set the level like that, and wonder if I should remove some and if so, how much?
 
By too bouncy I mean that during straight ride my headlite is constantly bouncing up and down on a level good road, and during turning it feels like my tire is going to bounce right out from under me. Almost like i have 100 lbs in my front tire! oil I used was "Maxima 15W". used 15 weight in the past with excellent results. This however, is just too strange...
 
You might want to do some alignment work on your forks. Loosen the top triple clamp and fender bolts and pump the fork a goodly number of times to try to align everything. This typically helps reduce the amount of stiction which makes the forks smoother.
 
Your wheel is bouncing going straight down a smooth road? Is the wheel balanced? How much air did you put in your forks? How does the front end feel if you hold the front brake on and try to compress the front end?

I run Maxima 20 weight in my Yammies and it rides real nice and smooth. Doesn't have extreme dive when braking either, which is what I like. I have the same 20 weight in my 1000, but I haven't tried that out yet.
 
Nessism said:
You might want to do some alignment work on your forks. Loosen the top triple clamp and fender bolts and pump the fork a goodly number of times to try to align everything. This typically helps reduce the amount of stiction which makes the forks smoother.
Click to expand...


True say! I had this problem when I first put my 650 back together. That's exactly how I fixed it now that I think about it. It was extremely scary going down the road before I did that.
 
When i installed the forks I put the axle on, bolted it up, and then tightened the fender bolts, an so on. However will try the "alignment" and see if it changes, as for the tire, when on the stand and the wheel is spun, there is no bulge or 'dip' in it, and the bounce is not timed rhythmically like a bump every revolution. I just wonder if there is a difference between weights of the "Maxima 15" and the "Bel Ray" 15W That I used before?
 
propflux01 said:
... used 15 weight in the past with excellent results. ...
Click to expand...
Have you used 15w in this bike before? Just because it worked with a previous bike does not mean it's right for this bike. :-k


propflux01 said:
... I just wonder if there is a difference between weights of the "Maxima 15" and the "Bel Ray" 15W That I used before?
Click to expand...
One would hope that 15w fork oil would be 15w fork oil. I have heard that it might not be necessarily true.

.
 
I also wonder about the tire being out of balance. Did you have it balanced on the rim before installing? Your bouncing issue sounds an awful lot like a tire out of balance. You won't see an unbalanced tire by spinning it on the rim. You need to have it spun on a machine or get a tire balancer that uses a bubble level.
 
As long as your bearings are alright, you can do a static balance with a couple of axle stands and a piece of rod or something. Just spin the wheel and see if it stops in the same spot every time. The point at the top is where you'll have to add weight. Keep spinning and adding weight until it stops in different spots every time. I've done this to lots of wheels and it always turned out smooth as glass. Your local bike shop will sell you wheel weights. Just tape them on at first to make sure before sticking them on more permanently as you may have to move them around.
 
try the alignment thing!!??!!

man this is how rookie mechanics get themselves KILLED!!!

there are warnings about suspension modifications.

every time that front axle comes off and goes back on, the forks need to be aligned on the axle to each other.

when the tubes and sliders come out of the trees they need to be set for equal height and spun to verify straight, tightening sequence starts at the top and goes to the bottom. just not from the middle out getting every thing straight and level takes a lot of practice.

less air softens the rebound heavier oil slows the rebound
less static pre load softens the ride.

your headlight bouncing around is no judging factor for how the new springs are working.
 
Yes, the bike has always had 15W in it. And I know this bike pretty good actually, and have had the forks off times before, just not had a problem like this. Everthing fork-wise was aligned, jsut as I have done in the past. never a problem till now. Tires are balanced using tire beads, and they are not new springs, they have been in the bike for several thousand miles. I used the headlight bouncing thing, as I test rode it at night, and the headlight verified (to me) what I was feeling, as it never bounced like that before....
 
I came home from work, and removed 2 ounces of fork oil from each leg, then rode. Bike settled down quite a bit. thinking perhaps it was hydro-locking and i just didn't see it?
And would also like to thank all those that responded for the advise and help.
 
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