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Suspension help
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kev



Joined: 18 Nov 2008
Posts: 6

PostPosted: Thu Dec 31, 2009 1:48 pm    Post subject: Suspension help Reply with quote

Hi guys, i have an SB6 luv it but......feels like its going to fall over going round corners/ bends, just tucks under so quick its scary. Tried setting suspension to stock settings i picked up off this site and was like riding a brick so hard it was trying to throw me off. Not sure if the bike has previously been set up for someone a lot heavier than me, possibly re-sprung i don't know. Any help or pointers much appreciated.
Cheers Kev
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oily



Joined: 05 Apr 2008
Posts: 4788
Location: worcestershire

PostPosted: Thu Dec 31, 2009 4:42 pm    Post subject: Reply with quote

Hi Kev,
Could be one of a hundred things Shocked
Are the headstock bearings good?
Is the rear shock set up properly?
How much wear on the front tyre and is the wear even?
Are the forks UP through the yolkes too far.
Are the front and rear wheels aligned correctly etc.etc.
Get everything else set up correctly before you blame the forks.
Has it handled like this since you've owned the bike?
Without riding the bike and with the limited information information you've given, my money would be on front tyre or headstock bearings Wink
Bring it down here and I'll give it a quick thrash for you Laughing
Or failing that, post a picture of you, flat out going round a bend and maybe we could tell somthing from the resulting high/low side. Laughing
Pompey's your man for setting up suspension Wink
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zombie



Joined: 10 Feb 2009
Posts: 272
Location: UK

PostPosted: Thu Dec 31, 2009 6:12 pm    Post subject: Reply with quote

We could add a wheel bearing check onto the end of that list.
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kev



Joined: 18 Nov 2008
Posts: 6

PostPosted: Thu Dec 31, 2009 8:41 pm    Post subject: Reply with quote

Well ....tyres appear ok although not a matched pair, forks 2/3mm above yolks i presume as standard, rear shock i've had to wind the spring compression ring all the way off just to get some movement.spring no. is 1091-24/3.00 ???, ive had bike up on abba stand and can't feel any play in head stock or wheel brgs. I suppose i should start with new set of tyres. And take it from there. possibly changing rear spring. The bike has ridden odd/strange since i've had it,sometimes get it on a white stripe and feels like its going to fall off it weird!!. I have played around wiyh tyre pressures still no change. So any reccomendations for tyres and pressures. Medium to fast road riding?
Cheers Guys.
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oily



Joined: 05 Apr 2008
Posts: 4788
Location: worcestershire

PostPosted: Fri Jan 01, 2010 11:24 pm    Post subject: Reply with quote

Kev, check the headstock bearings again. It's not "play" your looking for, just the opposite, too tight or notchiness Wink
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kev



Joined: 18 Nov 2008
Posts: 6

PostPosted: Sat Jan 02, 2010 12:45 pm    Post subject: Reply with quote

Will do, wont be today though bloody freezing out there!! I can't recall any probs although quite stiff i'd put that down to the steering damper. I'll get it up on stand and take panels off and check.
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oily



Joined: 05 Apr 2008
Posts: 4788
Location: worcestershire

PostPosted: Sat Jan 02, 2010 10:06 pm    Post subject: Reply with quote

Ah Ha..... steering damper. Forgot about the steering damper as I normally take them off or wind back the resistance to nothing. Try that first...wind the steering damper back to nothing and take it for a spin, see what difference, if any that makes.
All the problems you describe COULD be caused by the steering damper. Eliminate that first and get back to us Wink
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sapila racing



Joined: 14 Jan 2009
Posts: 67
Location: Athens, Greece

PostPosted: Sat Jan 02, 2010 11:36 pm    Post subject: Reply with quote

Like Oily says. the steering damper can be the cause, but get a pair of new matched tires also!
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Pompey



Joined: 31 Jul 2008
Posts: 2311
Location: Marlborough

PostPosted: Sun Jan 03, 2010 7:42 pm    Post subject: Reply with quote

Hey Kev, sorry to hear you are having problems with the suspension... sounds like a case of overcompensating the damping for an error in initial set up. I'll try to explain..

The problem with high end suspension of any type is that they are very sensitive to the slightest adjustments and contrary to popular belief they are very hard to find the sweet spot and very easy to chase an error from front to back and back again without being anywhere near close to a viable solution. Stock suspension on the whole for jap bikes are far better for offering a wider band of adjustment " acceptability" for the average fast road rider but rather then get the stock settings right people believe an expensive aftermarket shock to be the solution to their problems. It seldom is unless you go to a man who can to help them.

Basic rule number 1. You must try to get the front and back working at the same rate, even if not right it will still feel better then one right and not the other! I wont bore you with all the variants unless you want me to but the problems you are having sound like it could / should be the following...

A vague front end feel is normally the result of not enough weight thru the front of the bike. Why? Well it can be a number of things, an unusual rake angle due to soft rear set up, to much rear sag, weak rear spring OR and likely that your ride hieght adjustment is set on its lowest setting. This could also explain why the previous owner had wound the preload fully in to attempt to raise the back which is bad practice. It would make the ride feel rough over small lumps and bumps, to compensate for that error he probably softened all the damping in rear AND front. A false feeeling of improvement would be gained BUT the result of softening the front to lower the headstock and improve rake would result in the forks bottoming out on turn in for a corner especially under braking which would result the bike feeling like it is washing out from under you as you have already experienced. It almost feels like some one else is pushing at the bars and countersteering for you. All bad.

Solution attempt 1. You can drop the bars thru the yoke but before you do lets get under the seat / tank to the forward end of the shock and see where the ride hieght adjustment is... it is probably wound fully in so undue the nut for ten mil from fully in to start with. You should know if you are going in the right direction as the seat hieght will increase from the floor and probably mean you need to adjust the side stand but thats another story. The result will be putting more wieght back thru the front. You can then stiffen the compression because it is not compensating for the rake angle and that should stop bottoming the shocks and thus provide you with a bigger contact patch thru the tyres and a feeling of security thru the turn transition.

It also takes weight off the back to allow you to decrease the preload on the spring and soften the back end damping for both compression and rebound. A good way of checking is to get a mate to push down thru the petrol filler cap which is close to the centre of gravity and look to see if the front and back compress and rebound at similar rates.. Adjust accordingly before you try a road test.

Solution 2: Which I had to do with mine, is in addition to the first steps is to increase the oil in the forks to 15 grade from 10. It is not ideal and a bit of a cheat but is cheaper then paying for stiffer springs!

Anyway, let me know the result of checking your ride height adjustment in the rear shock and play with damping settings to where you think its close and let me know what clicks you have put in and we can go forward from there. Laughing
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Pomps
Bimota's Db2, Db5 ,Ducati's 851' 92, 888' 93, Honda blade' 93, Triumph speed triple' 07, kawasaki zxr 750 k1
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Pompey



Joined: 31 Jul 2008
Posts: 2311
Location: Marlborough

PostPosted: Mon Jan 04, 2010 12:16 pm    Post subject: Reply with quote

Kev, forgot to ask where you are located and if it is a viable distance from Wiltshire for a visit half way with spanners and flathead at the ready?
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Pomps
Bimota's Db2, Db5 ,Ducati's 851' 92, 888' 93, Honda blade' 93, Triumph speed triple' 07, kawasaki zxr 750 k1
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sapila racing



Joined: 14 Jan 2009
Posts: 67
Location: Athens, Greece

PostPosted: Mon Jan 04, 2010 5:56 pm    Post subject: Reply with quote

Pompey wrote:


Solution 2: Which I had to do with mine, is in addition to the first steps is to increase the oil in the forks to 15 grade from 10. It is not ideal and a bit of a cheat but is cheaper then paying for stiffer springs!


I also run the front with 15W oil and it has improved a lot.
Springs and damping are two completely dofferent things. In my case I don't really need stiffer springs as I weigh 70kg, and the front is now much better controlled with the heavier weight, sag is OK.
I also have the rear as high as possible, and I need more I think. In the meantime I lowered the yokes 5mm and it is better than before.

With stiffer springs you would need more damping, but W15 is already too much for cartridge forks. The correct solution would be revalving.

I also have a problem with the rear shock, as it is fine until it gets too hot during track days and looses damping almost completely. I 'll have to get it serviced soon.
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kev



Joined: 18 Nov 2008
Posts: 6

PostPosted: Mon Jan 04, 2010 9:10 pm    Post subject: Reply with quote

Cheers for the offer Duncan but i'm up in Manchester.........having said that if i can't get it sorted might have a ride down to you come the good weather. I weigh about 10 1/2 stone perhaps 11 with all my gear on. Will have a go at the things you have suggested, i'm still slightly unsure about the rear spring strength, had a look on ohlins site but got cofused i'm afraid. So i have got it quite soft with the spring compression ring wound pretty much right off, only way i could get any sag on the rear. From what you have said this could be part of the problem taking weight away from the front. Have a mate coming round on wed so will have a look and try adjusting. Looking out o the window and its snowing again so god only knows when i'll be able to test. As a side thought has anybody tried altering the rake through the adjuster? not sure if this bike has been raced at some point so could have had all sorts done to it. Anyways thanks for all input so far, just glad to know there's some pepes i can ask who know more than myself (not a lot). Cheers again guys.
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oily



Joined: 05 Apr 2008
Posts: 4788
Location: worcestershire

PostPosted: Mon Jan 04, 2010 9:17 pm    Post subject: Reply with quote

A dead give-away for en ex race bike is a drilled and lock-wired sump plug amongst other things Wink
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oily



Joined: 05 Apr 2008
Posts: 4788
Location: worcestershire

PostPosted: Mon Jan 04, 2010 9:35 pm    Post subject: Reply with quote

Well, well, well, Just as I thought, I'm abought dead centre between Marlborough and Manchester, with a big, heated garage, all the tools you can twirl and shed loads of tea and cakes Laughing Laughing
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Pompey



Joined: 31 Jul 2008
Posts: 2311
Location: Marlborough

PostPosted: Tue Jan 05, 2010 1:08 pm    Post subject: Reply with quote

Oily, you are a genius Exclamation Will travel for cakes anywhere, could pick up the screen at the same time...
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Pomps
Bimota's Db2, Db5 ,Ducati's 851' 92, 888' 93, Honda blade' 93, Triumph speed triple' 07, kawasaki zxr 750 k1
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