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Suspension/handling diagnosis

Discussion in 'Technical and Troubleshooting Torque' started by UDLOSE, Aug 3, 2011.

  1. I took my mates bike for a ride last night and the suspension does some weird shit! It's a 96 cbr900rr, i actually owned the bike a few years ago and it was great. My mate has stuff around with it a fair bit, steering damper, clip ons, the forks are raised about 5mm through the tripple and apparently set the suspension up. He is running metzeller M3s in decent condition.

    What it does;
    The initial turn in is very good almost twitchy but after you lean it say 30% it becomes hard to go further I tried to muscle it a bit and I didn't like the feel from the front tyre. You need to kind of hold decent force on the bars to maintain the lean and the bike just wants to stand straight up. When you countersteer into a low speed corner you actually feel/see the wheel turn into the corner, it's like the bike wants to stay upright and be steered like a car :/

    I backed the steering damper off to the lowest setting and it was still rubbish.

    I haven't had the chance to look at anything, I've got the bike at my place now so I'll take a look over it. I suspect the pressures are down which would explain alot of it but the bike still liked to stand up last time I rode it.

    Any ideas where to start? I suspect the bars should be put back to flush with the triple (standard for that bike).

  2. I'd start with tyres. Get the pressures sorted then you can move onto geometry.

    Check your sag settings front and rear. I suspect the rear may be a little on the soft side or the front way too stiff.

    As for the bars, having the forks higher in the trees will steepen your rake/trail giving you in theory better turn in at the expense of stability. I might be inclined to put it back to stock and go from there.
    • Like Like x 1
  3. first thing - tyre pressures.
    Then get it back to standard and start from scratch, unless you have notes of how it was setup when you owned it.
  4. When I owned it, it was my first big bike and I knew nothing about setup and didn't have the experience to read what the bike was doing so I set everything to bog stock (even preload) and it made a huge difference.

    The way I did my 675 and 600 was to set everything to stock, set the sag then make small adjustments to the dampening and fork height from there.

    It's just weird that it's so wrong! I've never felt that "bike wont stay leaned" on a bike before and never read that as a symptom in any setup guides I've read.
  5. Sometimes people say the bike isn't finishing corners. Similar thing. Usually a sign of not enough weight over the front on the power whether it's because of to soft rear or geometry (front preload too high/fork height)
  6. Ha ha well first your jumping from something that is stable yet turns on a dime to something....not.
    5mm is a huge drop in the front. Me thinking it would squiggle and squirm badly under brake and initially into corners too.
    First thing I would do is go back to stock settings on everything. Maybe 1 - 2mm down with the triples from stock if you want it to turn in a bit more. But at braking and stability's expense.
    Much easier to raise the rear for more turn in. It will spin up a bit more but that can be fun too.
  7. Nah I don't have high expectations of it. My daily is a 99 VTR1000F, the suspension is rubbish (much lower spec than the 900rr) but it's still way better than the state of my mates 900. I wasn't talking about pushing it hard under brakes and out of corners, I rode it for about 40km at the speed limit and it felt like a death trap.

    My mate is doing his first track day with me next weekend so we gotta sort his bike out or he'll bin it. He hasn't been riding due to having a suspended license. He was probably got used to it how it was but if he got back on it tomorrow (after 6 months of no riding) he'd be shocked, I know I was!

    Moving the front forks through is a funny thing, on my 675 I stiffened it up for better braking performance but then it turned in like a slug. I dropped the forks through more and it was great. Then I switched tyre brands and it was way too twitchy, put the forks back how they were and it was great again, but still kept the stiffness.