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Discussion Starter #1
I have a 2002 ST4s that's all stock with about 30,000 miles on in. Although I love the bike and it handles well, I have never been quite able to dial the suspension in to my liking. I'm 6 feet tall and 247 lbs. When I got the bike, as a matter of maintenance, I took the front forks apart, inspected them and changed the fork oil to a stock weight. I then reset every suspension adjustment (compression, rebounds, etc.) to stock and set the tire pressure to stock PSI. The bike has a set of Michelin Pilot powers I just put on them that are balanced perfectly. Despite over a year of ownership trying an infinite combination of front fork and rear shock settings I still suffer the following issues:

1) The front end always feels like it rides too high. This is despite my raising the forks in the sliders (lowering the front end/steering head on the fork tubes) 5 MM.

2) The front end rides harsh and hits bumps sharply, despite numerous readjustments of upper and lower fork settings and going to a lighter than stock synthetic fork oil and trying different tire inflation settings. Sometimes when I go straight over uneven roadways with repetitive bumps, I almost get a little subtle "jackhammer" type of bumpiness that is subtly transmitted to, but not through, the handlebars.

3) The back end sometimes feels just a little bit like it's going to slide when I am in a turn despite numerous readjustments of the shock and rear spring. I have checked the rear strut bar and it is adjusted to factory length.

4) Sometimes when changing direction and lean angle from left to right (good example is an S curve) the bike feels a little tipsy in the left to right - right to left transition.

I realize I am heavier than most riders but don't currently have the big money to swap out springs, etc. I have tried reading everything I can on suspension, talking to folks, etc. but I am mystified why I can't dial in the stock suspension a little better. One thing that did made the bike feel more planted and more flickable is I had an upholsterer cut down my seat about an inch last week and remove the center of the seat's dome - the seat used to feel like it was giving me a prostate exam and would put my shoulders over the handlebars.

I don't want you to think the bike is a total piece of crap handling wise, it's a ball to ride. It's just that I have owned other bikes in the past where I've been able to tweak or slightly modify the suspension to handle better and I just can't seem to dial out or really minimize these issues on the ST4s to my satisfaction. I will be taking my bike in next month to my friends motorcycle shop for some maintenance and will be asking him to look at the setup but for now would be curious to get member's input and ideas.
 

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It sounds like the front is to high and the rear is too compressed- and I can see that this would lead to less than ideal handling A proper spring for your weight will not be too expensive. At the very least the rear shock and fork probably need a fluid change, after 8 years and 30,000 miles. Getting the rear sag correct with a proper spring will make all the difference, handling wise. I have had really good results with NCRick from Cogent Dynamics, he is a sponsor of this site and has done work for lots of folks here.
 

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The bike's suspension is reportedly set up for a mythical 160 lb. Italian rider. At 247 lb you definitely need a heavier rear spring for starters.
 

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Life is too short to worry !
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I would echo both the comments from Butch & Bill.

The rebuild on the rear shock is scheduled for 18,000 so at 30,000 yours is way overdue for a rebuild and a new spring even it had been originally correct - The cost is not too bad compared with a new Ohlins and worth getting a quote for.

The standard setting for the ride height si also not very popular and will add to the problem of a tail heavy bike.
A new , heavier , spring alongwith new oil and raising the ride height should sort things out. Going over ripples with the wrong damping set-up (too little comprression and too much rebound) can result in pump down where the suspension does not have time to rebound and thus (possibly in your case) you eventually run out of suspension until you reach a calmer bit of tarmac and the forks have time to rebound properly ready for the next bump.
 

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I'm with the new stiffer spring too.

As you're a little short on funds though, I also most definately go with Gearbox's ride height suggestion - this will cost you nothing (assuming you can undo the probably seized bolts of course) and will transform the handling no end and the bike will be much more flickable..

Lower the wheel (with the bike on the centre stand) till the tyre just touches the ground if the tyre is new, maybe 5-10mm shy off the ground if it's worn.

It's also a good idea to completely seperate the tie bar from the two eyelets, just to make sure that they are both screwed back in with an identical number of threads. Also put some copperslip on the threads, and make sure that you're happy that there are a secure amount of threads after the adjustment.

The tie rod/ride height adjuster has a right hand thread at one end, and a left hand thread at the other.
 

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http://www.ohlinsusa.com/us/
I just had my shock serviced and the remote preload repaired for $130. The turnaround was a little slow for me, but the work is quality, and the folks on the other end of the phone are very polite and knowledgeable. Ohlins USA is in Hendersonville, NC. They do a standard shop rate of $75 plus parts.
 

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Discussion Starter #7
UPDATE: I replaced the fork & shock springs with ones that were more suited to my weight. It took care of most of my problems. The problem with the front end always feeling like it rides too high was cured by fixing a problem with the rear shock installed spring length. The previous owner had the rear installed spring length at 135 MM for some reason & the shop returned it to 150 MM.

I am still mystified by the front end riding harsh and hitting bumps sharply. I've taken the forks off the bike & into shops twice. Despite dis-assembly, numerous readjustments of upper and lower fork settings and previously going to a lighter than stock synthetic fork oil, I still get a "jackhammer" type of bumpiness that is subtly transmitted to, but not through, the handlebars. I've even had the front wheel checked for balance and and if the tire/wheel was out of round. The tire and wheel was fine.
 

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Good. It sounds like you're getting there now.
This jackhammer business, it wouldn't be anything to do with brakes/discs would it ?
Has the bike ever been in a front ender that you know of ?
 

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Discussion Starter #9
No, the bike doesn't seem to have been in any front end accidents from what I can tell and the brakes rotors are not out of round, etc. I'm wondering if there's a plugged orifice in the forks somewhere or something of that nature?

Could a bearing in the steering head cause this? But that doesn't make sense because I can minimize the jack-hammer/pogo effect with the suspension settings but I can't make it go away entirely. @#$%^&$!!!!!!!!
 

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Loose or knackered steering head bearings are certainly worth looking into.
I was just wondering whether the brakes were sticking, or warped disc/s or stiction in the forks re the front ender question.
 

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I bought a 2001 st4s with 25000kms on it recently . The bloke i bought it off was a big bopper and he put a heavy duty spring on the shock . Its crap for me cause im 75kg (11stone) ringin wet . I,m gunna change back to an original spring , if you want mine your welcome to it if you wanna pay the frieght from australia
 

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Discussion Starter #14
Further Update: Thank god for Andrew Trevitt from Sportrider magazine. I found a clip from his book on suspension adjustment. His advice from the book was very detailed and his advice was perfect. I dialed out all the compression and rebound from the front forks (all clicks out) and added pre-load (about a turn and half) to the front end. It really improved handling and got rid of the "jackhammer effect."

P.S. appreciate the members offer on the spring upgrade, but I previously added upgraded springs for my heavier weight.
 

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Discussion Starter #15 (Edited)
Awhile back, Erikrichard P.M.'d me He had a similar problem with his ST fork and recommended I removed about a 1/2 into to an inch of fork oil from the forks. I removed an inch and the bike sure rode better.

Also, I have tried two times previously to increase the rear ride height via extending the "monoshock" (as the manual calls it) strut bar. The previous two times I couldn't budge it, ran out of time and gave up. This time I removed the strut again and coaxed the nuts on the strut loose with a torch. As the members here recommended, I extended the strut until the rear wheel just about touched the ground with the bike up on the center stand.

Took the bike for a really short ride, the front end really seems to feel more planted and the bike seems to turn sharper. Makes me really appreciate the wisdom of all the members on this site.
 

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Just as a side note, I have tried two times previously to increase the rear ride height via extending the "monoshock" (as the manual calls it) strut bar. The previous two times I couldn't budge it, ran out of time and gave up. This time I removed the strut again and coaxed the nuts on the strut loose with a torch. As the members here recommended, I extended the strut until the rear wheel just about touched the ground with the bike up on the center stand.

Took the bike for a really short ride, the front end really seems to feel more planted and the bike seems to turn sharper. Makes me really appreciate the wisdom of all the members on this site.
You may want to dial in your rebound and compression damping too, after raisng the rear, especially the rebound as it will now unload much quicker. :)
 

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David Alexander from FS2 Fluid suspension science did a work shop at Seattle Ducati last year. David produced a great hand out on how to set up suspensions. does anyone out there still have one?
 

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I'm having the same subtle "jackhammer" issue on my 2002 ST4S. It seems to come on at speeds over 65 MPH on less than perfectly smooth roads. I'll be trying these tips once I get the fuel issues sorted :/

Sent from my HTC Vision using Motorcycle.com App
 

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Further Update: Thank god for Andrew Trevitt from Sportrider magazine. I found a clip from his book on suspension adjustment. His advice from the book was very detailed and his advice was perfect. I dialed out all the compression and rebound from the front forks (all clicks out) and added pre-load (about a turn and half) to the front end. It really improved handling and got rid of the "jackhammer effect."

P.S. appreciate the members offer on the spring upgrade, but I previously added upgraded springs for my heavier weight.
Where did you find said clip? Thanks

Sent from my HTC Vision using Motorcycle.com App
 
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