After scattering various questions and experiences across a variety of revived zombie threads, I figured I should do the reasonable thing and just start a new thread of my own.
Last fall, I bought a 2002 C10 with 12k miles, in excellent shape, but it had been sitting for most of the last 15 years (indoors, thankfully). After doing a full carb rebuild this winter, along with brake flushes, clutch system rebuild, valves, and a bunch of other minor stuff, I got it on the road this spring, but have been struggling with some handling issues that just just makes me uneasy, especially at highway speeds. When I got the bike, it had OE-spec Dunlops on it, in good shape with plenty of tread, but a late 2005 date code, so after doing just 100 miles on around-town shakedown riding, I promptly swapped them for a fresh set of Avon Spirit STs in 110/80ZR18 and 150/80ZR16. I don't know if the feeling was there with the old tires, or if I was just riding it so cautiously that I didn't notice, but ever since I've been on the new tires, it feels less stable than any bike I've ridden (granted, not a lot, and none as heavy or with as much fairing).
It just feels like it wants to wander at slow and mid speeds, and on the highway (above 60mph) is feels like it wants to wander and wobble at a slow rate. It's not nearly as rapid as a proper death wobble/tank-slapper, but still kind of unnerving. The turn-in effort is very, very minimal, and odd for such a big heavy bike (my Ninja 250 took a lot more countersteering effort). I'm not sure if that's part of cause or effect.
Here's a list of things I've done on the bike in attempts to suss out the issue:
I'm still trying to get to the bottom of it, and getting close to swapping my old tires on to see how that feels. The Avon's don't look uneven and I can't feel any wobble, vibration, or lumps, either rotating by hand, or when riding. I've got about 150 miles on them so far.
This afternoon, I did try loosening the steering bearing 1/8 turn, and maybe it helped, but still felt weird. I rode about 30 minutes, and the last 10 on slower city streets felt worse. When I got home, my damper (still connected) seemed stiffer, and the adjustment knob was jammed. I think it may be heat-soaked, so it probably stiffened up as the ride went on. It's a cheap Chinese unit, and I bet it's over-filled with oil so there's not enough expansion volume. I rode it this time without the bags, but generally intend to ride the bike with bags (it's a big part of why I got the bike. When I'm just jaunting around town without need of storage space, I take my 600).
I loosened the bearings up another 1/8 turn, and the bars now freely bounce off the stops and back to the other side, but still no play. I also disconnected my damper. so I'm going to try that again and report back.
I can't think of much else to try other than steering bearing adjustment and tires. At this point I may be hoping it's the tires, as I don't know what else to try. I am thinking even if it gets over this wobble, these are not the style of tires for me. I would prefer more turn-in effort, and feel like the sharp profile (and maybe the 110 front?) is part of what makes it sensitive and twitchy?
Last fall, I bought a 2002 C10 with 12k miles, in excellent shape, but it had been sitting for most of the last 15 years (indoors, thankfully). After doing a full carb rebuild this winter, along with brake flushes, clutch system rebuild, valves, and a bunch of other minor stuff, I got it on the road this spring, but have been struggling with some handling issues that just just makes me uneasy, especially at highway speeds. When I got the bike, it had OE-spec Dunlops on it, in good shape with plenty of tread, but a late 2005 date code, so after doing just 100 miles on around-town shakedown riding, I promptly swapped them for a fresh set of Avon Spirit STs in 110/80ZR18 and 150/80ZR16. I don't know if the feeling was there with the old tires, or if I was just riding it so cautiously that I didn't notice, but ever since I've been on the new tires, it feels less stable than any bike I've ridden (granted, not a lot, and none as heavy or with as much fairing).
It just feels like it wants to wander at slow and mid speeds, and on the highway (above 60mph) is feels like it wants to wander and wobble at a slow rate. It's not nearly as rapid as a proper death wobble/tank-slapper, but still kind of unnerving. The turn-in effort is very, very minimal, and odd for such a big heavy bike (my Ninja 250 took a lot more countersteering effort). I'm not sure if that's part of cause or effect.
Here's a list of things I've done on the bike in attempts to suss out the issue:
- Adjust rear shock sag and damping (it's got a Hagon shock with hydraulic remote preload adjustment). I can bet between 1" and 1.75" of sag, but neither seems to make much difference
- Adjust front fork preload. Also did not make much difference
- Re-torque all motor mounts. The rear two were pretty loose, while the fronts were fine. I think? it may have helped the high-speed feeling, but if so, it was small.
- Check rear swingarm and re-torque bearing adjustment. It was right about at spec anyway. No apparent change.
- Full front fork rebuild with Racetech emulators and 0.90kg/mm springs. I had planned on doing this anyway, so it wasn't primarily to address the handling issues. No apparent change on stability. The ride quality is so much better, though! I highly recommend the mod.
- New steering head bearings. The old ones were about as tight as you could get them with my adjustable spanner, yet still didn't feel like they were binding. The upper race had grooves from the rollers all the way around, which suggests it had been over-tightened for a while, and after taking it out and cleaning it, I could feel slightly notchyness in the bearing, but I never noticed it on the bike. I set the new bearings to what felt good, with minimal drag and zero play.
- Steering damper. I realize it shouldn't really be needed, and probably doesn't serve any benefit for this kind of slow and low-frequency, but it wasn't that much work, and I was curious to experiment.
I'm still trying to get to the bottom of it, and getting close to swapping my old tires on to see how that feels. The Avon's don't look uneven and I can't feel any wobble, vibration, or lumps, either rotating by hand, or when riding. I've got about 150 miles on them so far.
This afternoon, I did try loosening the steering bearing 1/8 turn, and maybe it helped, but still felt weird. I rode about 30 minutes, and the last 10 on slower city streets felt worse. When I got home, my damper (still connected) seemed stiffer, and the adjustment knob was jammed. I think it may be heat-soaked, so it probably stiffened up as the ride went on. It's a cheap Chinese unit, and I bet it's over-filled with oil so there's not enough expansion volume. I rode it this time without the bags, but generally intend to ride the bike with bags (it's a big part of why I got the bike. When I'm just jaunting around town without need of storage space, I take my 600).
I loosened the bearings up another 1/8 turn, and the bars now freely bounce off the stops and back to the other side, but still no play. I also disconnected my damper. so I'm going to try that again and report back.
I can't think of much else to try other than steering bearing adjustment and tires. At this point I may be hoping it's the tires, as I don't know what else to try. I am thinking even if it gets over this wobble, these are not the style of tires for me. I would prefer more turn-in effort, and feel like the sharp profile (and maybe the 110 front?) is part of what makes it sensitive and twitchy?
so many owners have either cut down the top edge or get an aftermarket version like Cee Bailey's which I did.
