Bouncy front end on a 99 ST 1100 with 49K.

EZ-STRider said:

the entire front end sways up and down on uneven surfaces.

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Do you mean the forks? Or do you mean the whole bike is moving up and down on the front, as if there is no fork action at all? Too heavy a fork oil could cause that.

Do the forks compress easily, or not, if you hold the front brake on and push forward?

The previous owner might have upgraded the front springs, can you talk to him?
Also perhaps the front end is not aligned properly after the last tire was installed.

It seems that the whole bike is going up and down on the front, as if there is no fork action at all. The forks do compress when the brakes are applied, to what degree i am not certain as i have no previous experience with this bike. The previous owner did not do any modification on the bike, to the best of my knowledge. The issue was present even when the old tire was on. i will try to align the front end as suggested on one of the threads by loosening the pinch bolts and depressing the forks a few times. Any other suggestions?

You should be able to push/compress the forks easily about half way through full travel, at least. Can you still talk to the PO to ask if he did change the fork fluid and what he used?

The forks do compress easily and go about halfway as expected. I had mentioned the problem to the PO and he confirmed that he did not change anything on the bike at all other than the rear tire and the occasional engine oil (he only had it for a year). I am the third owner and not much is known about the first owner.

It would be a good idea to state the year and abs (if you have it) in you profile to help ID some specific things on your Bike
How is the Back adjusted Stiff, loose? it will affect the front action.

Also what PSI are you running in the front and rear, are you SURE your pressure gauge is correct?
I once had a gauge that read 10 lbs high and couldn't figure out why it slid around in corners.

Not knowing whether or not the forks have ever been re-built with new fork oil would be MY next step. That's not just leaving in tack and changing fork oil either. That's like changing motor oil and not changing filter leaving some of contaminated oil in. They need to be removed, dis-assembled, throughly cleaned internals and new fork oil put in to the specs listed for those forks. Remember to, that compression dampening is only on left fork, rebound dampening, both.

The air pressure is 38 psi and has been confirmed with two different gauges. The year is 1999 and it a non ABS model with just 49k on the odometer. I tried different settings at the back, from the maximum to the minimum, it did not make much difference. It is currently set up at the second notch from the minimum compression and the dampener is set on the soft side. Everyone seems to point towards the fork oil and forks servicing/cleaning. I can get that done and see what happens. Anyone has any feedback about the Michelin Pilot road 3 tyres?

38 Front is what I run, I had one of the PR4 GT (Heavy sidewall) fronts and dropping to 36 helped some as the ride was a little harsh.
I ran PR3s at 38 no problem
It would probably be good to service the Forks, it sounds like the previous owner did only the most basic service, Oil and Brakes.
Cupping could easily mean not enough front Dampening.
When you depress and let go is there reasonable dampening in the front.

Also If you Increase Dampening in the rear you might feel less POP from the front.

When depressed and let go the front end springs right back with a bounce. I do not see much slowing or dampening action. Also when removed from the centre stand the front end drops quite a bit and seems soft. I will have to compare the motion with another ST to see the difference. Thanks for the suggestions folks. I will have to service the forks first it seems and then find out if that works. If not I will ask for further help at that point. The front tyre was severely cupped, that seems to be the effect and not the cause. What are the causes for cupping, may be that is the answer to my issue.

EZ-STRider said:

When depressed and let go the front end springs right back with a bounce. I do not see much slowing or dampening action. Also when removed from the centre stand the front end drops quite a bit and seems soft. I will have to compare the motion with another ST to see the difference. Thanks for the suggestions folks. I will have to service the forks first it seems and then find out if that works. If not I will ask for further help at that point. The front tyre was severely cupped, that seems to be the effect and not the cause. What are the causes for cupping, may be that is the answer to my issue.

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Some cupping is normal, its a result of the braking forces on the tire. Excess cupping can be caused by underinflation, or probably other misadjustments in the forks.

Change the fork oil to the proper level, adjust the preload to the proper sag, and report back.

I am having a similar problem so I look forward to seeing your solution.opcorn

EZ-STRider said:

When depressed and let go the front end springs right back with a bounce. I do not see much slowing or dampening action. Also when removed from the centre stand the front end drops quite a bit and seems soft. I will have to compare the motion with another ST to see the difference. Thanks for the suggestions folks. I will have to service the forks first it seems and then find out if that works. If not I will ask for further help at that point. The front tyre was severely cupped, that seems to be the effect and not the cause. What are the causes for cupping, may be that is the answer to my issue.

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Well, No.1: radials tend to show cupping more than bias....#2: underinflation mutiplys that(once cupping starts, CANNOT be reversed).......and lastly, if ya' want the tires to give good handling and maximize mileage, inflate to tire manufacturers specs. on sidewall, not what bike manufacturer has on their cute little sticker on frame under seat, or whereever its located. My bet that is 42psi. A fork rebuild, using one weight viscosity HIGHER than originally listed(seperate subject if disputed) is your first step, BEFORE replacing front tire. If you choose to follow that path, be careful, as the permanent grin may be hard to remove.

Thanks everyone for taking the time to provide the suggestions. I tried the front wheel alignment procedure as suggested, by loosening the pinch bolts and depressing the front end hard a few times. That unfortunately did not make any difference. next will be trying a few days with the manufacturer recommended inflation on the tire and thereafter the fork oil replacement/service. Will post the result ..hopefully with a smile.

In reading this thread I think there are potentially one or two issues. One the fork oil viscosity is to heavy and/or there is to much fork oil reducing the amount of air space in the forks providing less dampening.

The only real way to check either is to replace the fork oil with the Honda recommended weight and the appropriate amount of oil.

One other issue is the road. One my ST1100's there are a couple of roads near where I live that are just bouncy roads. And my bike only have front end bounce on those roads.

Also check the front wheel for roundness, not the tire.

Grabcon said:

One other issue is the road. One my ST1100's there are a couple of roads near where I live that are just bouncy roads. And my bike only have front end bounce on those roads.

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Same on a few roads over here, as if the asphalt machine crated slight "ripples" with the crests at a distance of 20 to 30 ft...

Race Tech recommends straight wound springs , not progressives, BTW, because progressives are too difficult to set up properly ( the preload ). And they say the stock springs are way too soft ( according to their spring rate calculator they are perfect for a rider that weighs ZERO pounds ! ), and Honda compensates for the soft springs with way too much damping.

If you want to improve on the old '98 design , install a Race Tech Gold Valve and Emulator kit and the proper straight wound springs for your weight. The result is a "plush, but firm" ride. I'm happy with the results. You can find the kit & springs for less than list on Amazon, etc. Sonic springs are a little cheaper than Race Tech springs, too. And make sure your fork bushings are in good shape.

+1 on the recommendation that the only way to service the forks is to unscrew the top "plug" ( dissasemble, basically ) and dump, flush with ( ATF & pump & dump ) x 3. If the ATF keeps coming out really nasty looking, try some Simple Green to help the process along. I recently serviced my front forks and the cartridge side was really dirty after only 20K miles. Using the Simple Green helped clean out the gray stuff really well.

Some very interesting observations folks! Its comforting to know the amount of support out there for the ST owners. One of the mechanics I took my bike for a test drive recently, mentioned that my forks are 'stiff', very similar to what Grabcon has suggested. When buying a used bike over the internet one can only do so much. I drove the bike round the block and everything seemed great!. It was only afterwards that I felt the annoying bounce. The PO says that he did not feel anything, which is hard to believe.

The issue is not with the roads in my area, it is apparent everywhere between the 60-70Km/hr speed. It is quite possible that the original owner may have tampered with the forks or modified them as per his requirements. I always ride single and weigh around 175 lbs. maybe he was riding double and on rough roads. I think a good Honda mechanic should be able to pin point the issue, but i am not sure where to find one. I will have to try and eliminate one thing at a time. This afternoon I increased the air pressure to 42 psi as recommended and drove for almost 80 Kms...unfortunately it did not make any difference. Next would be servicing the forks...

I wasn't aware that the PO might have tempered with the forks... or maybe not... might be that they just have never got serviced/overhauled and are only in need of some TLC...