Do we have any suspension guru's hang around here?

[Dark]

Just wondering as i'd like to ask them about a few handling issues i'm experiecing.
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My Bikes in order:- Yamaha RXS100 / Suzuki X7 250 / Yamaha RD350LC / Kawasaki
KR1S 250 / Kawasaki ZXR750 H2 / Honda C50 / Kawasaki ZX7R P5 / Kawasaki ZX10R / Suzuki GSXR 400 / Honda CBR1100 Blackbird & Yamaha FZR 600

[feef]

not a 'guru' but I can try and help a bit. wassup?

a
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Mudskipper wrote: feef, that is such a beautiful post that it gave me a lady tingle
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[Dark]

ok, here goes:-

The bike is fine at a moderate pace, which is quick enough for most rides, but i've had problems at a lot of corners when pushing the pace. I'm finding it hard to describe, but i'll have a go.

After braking and turn in i pick up a smidge of throttle through mid corner and then get on that gas past the apex. This is fine up to a point. Once the bike gets to a certain angle of lean, which feels about three quarters of the possible lean angle it just doesn't want to lean any more, it feels like it just stops leaning. If i try and force it to lean a bit more the front then feels vague and if i force it some more it slides.

The problem feels worse when i hang off, its probably not, but it feels worse. So that means no knee down until i sort it out I have touched down twice i think but the front felt absolutely terrible. As you can imagine a tightening radius corner presents a bit of a problem, because as the radius tightens i lean over more and more and then the bike doesn't want to lean anymore but the corner is continuing to tighten, this is where i start to pray the front isn't going lto et go.

The only thing i can think of is that even the faintest wiff of throttle mid corner is compressing the rear shock and lifting the front a bit causing the front not to be planted enough at high lean angles. Therefore my plan is to stand the bike on its nose a bit more, thats why i pushed the forks through the yokes a bit which i think may have helped the mid corner problem very slightly but not enough. So the next step i think is to back of rear preload and see how that feels and if thats not enough maybe jack the rear end up with some shims. Of course i will have to revisit my damping settings again.

Since i pushed the forks through the yokes i've noticed some instability on the bumpier sections on constant throttle whilst leant over by small amounts. Its not bad in a straight line, but as soon as you lean it over the bumps cause it to wobble around a bit. It feels like the bike hits the bump and the suspension compresses ok (its quite a harsh ride, but i don't mind that) but the bike takes a bit to settle down after the bump for a bit. So i'm thinking i may need a little more rear rebound.

What do ya reckon?
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My Bikes in order:- Yamaha RXS100 / Suzuki X7 250 / Yamaha RD350LC / Kawasaki
KR1S 250 / Kawasaki ZXR750 H2 / Honda C50 / Kawasaki ZX7R P5 / Kawasaki ZX10R / Suzuki GSXR 400 / Honda CBR1100 Blackbird & Yamaha FZR 600

[feef]

what bike is it, and what adjustability do you have on your suspesion?

a
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Mudskipper wrote: feef, that is such a beautiful post that it gave me a lady tingle
Windchill calculator - London Bike parking
Blog and stuff - PlentyMoreFish dating

[Dark]

an 05 ZX10R and the suspension is pretty much fully adjustable. Front has rebound, compression, preload and the rear has the same
____________________
My Bikes in order:- Yamaha RXS100 / Suzuki X7 250 / Yamaha RD350LC / Kawasaki
KR1S 250 / Kawasaki ZXR750 H2 / Honda C50 / Kawasaki ZX7R P5 / Kawasaki ZX10R / Suzuki GSXR 400 / Honda CBR1100 Blackbird & Yamaha FZR 600

[feef]

dropping the forks thru the yokes will also have steepened your head angle, making the front less stable, hence the slight skittishness you detect at speed un bumpy terrain.

If you want to Stop the back end sqautting under power, you should increase pre-load, as that will stiffen it. More rebound damping just means that after the back HAS squatted down, it'll take longer to come back up. too much rebound damping and you can actually, over bumpy terrain, completely compress the spring before the shock's allowed it to recover from the first couple of bumps.

do you feel the back end moving at all when cornering? I mean feel the suspension working? or does it feel solid and harsh over bumps?

if the back was squatting too much, and the front was unweighting, you'd probably detect an element of headshake from the bars, especially over uneven roads. can you feel anything like that?

a
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Mudskipper wrote: feef, that is such a beautiful post that it gave me a lady tingle
Windchill calculator - London Bike parking
Blog and stuff - PlentyMoreFish dating

[NSR Mick]

What condition are your tyres in.
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If you dont like the way that I ride.......Stop trying to keep up!!!

[dainesefreak]

Similar lines to Mick, what tyres are they?

[Dark]

Metzeler Racetec K0's (the softest compound) in good condition too. They are currently at 30 psi front and 33 psi rear
____________________
My Bikes in order:- Yamaha RXS100 / Suzuki X7 250 / Yamaha RD350LC / Kawasaki
KR1S 250 / Kawasaki ZXR750 H2 / Honda C50 / Kawasaki ZX7R P5 / Kawasaki ZX10R / Suzuki GSXR 400 / Honda CBR1100 Blackbird & Yamaha FZR 600

[Dark]

[feef]

the problem could possibly be due to a combination of sag and ride height settings that leaves your bike riding high up front. Having a front tyre skip over bumps on the exit of a turn is a sign that the fork is topping out--without enough sag to allow the suspension to sink into depressions in the road.

Check your front and rear static sag to ensure correct spring preload.

set your suspension and geometry back to stock (or near as damnit)

With the preload set, take your bike for a spin to determine if there's any change in its behavior. If the problems persist, backing off the front preload will drop the front of the bike a bit, quickening the steering and letting the wheel track over bumps more effectively. If, however, the fork starts to bottom under braking with the preload backed off, the forks can be dropped thru the yokes to sharpen the steering while keeping the original preload setting.

Static sag is the amount your bike's suspension compresses when you sit on it. It's best to have two friends to help-one to hold the bike while the other one measures-while you (fully dressed in your riding gear) do the compressing.

First, extend the front suspension completely. Measure from the seal to the lower yoke for a conventional fork, or to the axle clamp for an inverted fork. Call this number L1. Sit on your bike in a normal riding position, and have one helper steady the bike. Your second helper should push down on the fork, let it extend slowly and then re-measure as before. This number is L2.

Finally, the fork should be extended by hand, settled slowly, and re-measured. This figure is L3. Halfway between L2 and L3 is where your suspension would settle if there were no friction in the system. Static sag can be calculated as follows: sag=L1-(L3+L2)/2. Repeat this process to determine the rear sag-measuring from the axle to a point directly above on the frame for each of the numbers. If you have too much or too little sag, dial in more or less (respectively) preload as needed.
____________________
Mudskipper wrote: feef, that is such a beautiful post that it gave me a lady tingle
Windchill calculator - London Bike parking
Blog and stuff - PlentyMoreFish dating

[dainesefreak]

I changed my tyres from Diablo Corsas to standard Diablos and the bike feels more planted. Funnily enough I was reading a few months old Bike mag this morning (gotta do something when I'm on the bog) with a K5 gixer and he was complaining about the bike bouncing/throwing him about on his commutes unlike the K3 he'd had before. He actually changed tyres a few times and ended up sticking to sports touring tyres like the Sportec M1's and said it cured the problem.

I was at the stage you're at now a couple of months ago and even got to the downloading setup guides of the web bit. I haven't touched them after a tyre change and fiddling with my pressures. Admittedly for me the tyres really needed changing though and it's a bit of an expensive test if it makes no difference to your problem.

[Dark]

I've just had a reply back from a friend who has the same bike as me, he has just ran his in and is attempting to set his suspension up too

[feef]

[dainesefreak]

I also installed a PCIII which did wonders for the injection setup and made the bike 100% more rideable through corners/part throttle/neutral-throttle situations. The combination of the two have made a huge difference. It's almost like a steroid injected 125.

[Dark]

[feef]

[Dom_]

I'm no expert but 30/33 seems awfully low for a bike of that size, i run higher pressures than that on my 400, and back when i worked at a bike dealers all the new bike (big ones anyway) were filled 36/42 iirc.
Although not saying yours should be that high, you could possibly try 33/36 and work from there etc..?

[Dark]

[feef]

been doing some digging, and found these 'recommended' settings for the '05 ZX10R


front preload: 5 lines showing
front rebound damping: 4 clicks out from full stiff
front comp. damping: 7 clicks out from full stiff
rear preload: 14mm thread showing
rear rebound damping: 1.5 turns out from full stiff
rear comp. damping: 3.5 turns out from full stiff

This is with the forks flush with the yoke.

how do your settings compare with those?

Might be worth doing a comparison to see if there's anywhere that it's widly different.

a
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Mudskipper wrote: feef, that is such a beautiful post that it gave me a lady tingle
Windchill calculator - London Bike parking
Blog and stuff - PlentyMoreFish dating

[Dark]

[Dark]

[feef]

your rear compression is firmer, and your front rebound, less than the "suggested" settings. That 'could' give the feel of an unstable front end, and until you get the power on, once past the apex, and shift the weight further back, it'll be chattering a little, losing a bit of grip.

you're right, that it doesn't take into account rider weight, but other than front rebound, and rear compression, your settings seem pretty close.

try tweaking the front rebound damping up a bit, and see if that helps.

a
____________________
Mudskipper wrote: feef, that is such a beautiful post that it gave me a lady tingle
Windchill calculator - London Bike parking
Blog and stuff - PlentyMoreFish dating

[Dom_]

[Dark]