| Author | Message | ||
     John_vreede |
Hi all I've just bought an '06 XB12XT with 45k miles on the clock. The handling leaves me feeling insecure after my previous bike (M800S Ducati). Suspension is way more plush but under-damped by comparison (winding up the preload a turn and upping the rebound setting 1/4 turn helped but its harsher and still doesn't inspire confidence). What I didn't expect was that it doesn't like changing direction in tight twisty stuff (30-50mph corners), something Buells are good at. I can't see any inherent reason a Uly should behave like this, so my question is where to start looking to fix/improve it? - jv | ||
| Cyclone8u |
With 45K I would say the rear shock is probably spent, and the forks are most likely due for a rebuild. You can buy a new shock for fairly short money, but given the performance you're looking for I'd opt to find a shock rebuilder that would give it the Race Tech treatment. Likewise with the front end, Race Tech valving and some springs to match your weight and riding style may be I'm order. Don't forget the steering stem bearings, at 45K they've probably lived their life by now. | ||
| John_vreede |
Thanks, I suspected that's where I'd have to start but I don't know and of the 'lore' surrounding Buells. The shock and spring are too hot to touch comfortably (~120F?)and that can't be good for the performance of any shock. Is that normal for an XB? What can be done to reduce the temperature? Does that heat have any affect on the electronics (EMC?) under the seat - jv | ||
| Screamer |
Second on the shock and especially the steering stem bearings (on set #3 at 27k on my 06 Uly). Heat was typically not an issue for the Ulysses ECM. | ||
| John_vreede |
I'm about 80-90% there but its not completely to my liking yet, for which I'd like some feedback. Firstly what worked and what didn't: - Checked the bearings per advice above. The wheel bearings were ok but there was a SLIGHT tendency for the front wheel to self-centre. I've felt damaged head bearings before and the they clicked from indent to indent on the race, this was smooth, even if it did swing to the centre, so I figured it was good enough if not perfect. - When cornering the bike didn't turn in naturally, you had to push it into the turn. Then I seemed to have to push back on the inside bar to hold it on line through a turn. - As mentioned above, the shock did need rebuilding so booked the bike in with Robert Taylor https://www.youtube.com/watch?v=8VGl9jdz4M4. - Just before delivering the bike to him, I figured maybe it was not so smart to go with headset bearings that were not perfect, so I replaced them with OEM parts. What a difference! Now the bike just flopped into the turns like the front tire was flat, even though it was in mid -30's psi. - Pumping the front up to an indicated 40psi seemed to cure the 'flopping in' just like it did on my old dirt bikes. No wonder I had to push on the inside bar, the duff head bearings were masking the flopping in. - Even though the major problem was fixed, I went ahead with the rebuild of the shock and front forks anyway, since I wanted to know what effect that would have. They re-shimmed both rebound and compression stacks on the shock and both fork legs, and added new single rate springs both ends as well as the normal seal replacement. He also confirmed that shocks were supposed to operate above 60C (140F) and the underseat heat on the Buell would just stabilise the shock temperature more quickly. Anything less than about 100C (210F) he said was OK. - He set it up with 53mm sag to give the same ride height I given it to him with. Its more sag than the books say is desirable, but I'm happy with it as it gives me a more compliant ride (more extension travel as a proportion of total travel) since I don't hit bumps as fast as racers, so long as it has enough rebound damping to prevent wallowing, which it now does. - It doesn't nosedive like it used to when the brakes are used hard, the extra control is really noticeable. - The shock now operates in the design range for rebound and compression damping. (were way further in on all settings when I got the bike) - He also drilled and tapped a fill screw into the banjo of the hydraulic preload adjuster and added oil to restore its full range of movement (first 5 turns did nothing before). - Other than that there is not a lot of noticeable difference for all the money spent ($1800NZ). The before and after traces on the shock dyno were very similar, so even worn, the Showa shock had aged well. - The tires are well worn but even over the whole tread, no hint of flat spots. - The suspension guy thought the tires should operate at 32f/35r psi but it still felt like the front tire was flat so I'm back to 40f/42r psi. - He gave me a ranges of suspension settings for all parameters to experiment with including dropping the fork legs down through the triple clamps to try to slow the steering up. He also told me the order to make the changes in, and a process to evaluate them, which I can post if anyone is interested. - So far I've only tried the tops of the fork legs flush with the top triple clamp (about 20mm (3/4") drop) but it made no difference to the turn in, I still need tire pressures at 40f/42r to get (nearly) neutral steering. My question is do other Uly owners have to stop the front wheel turning in too far when cornering at the manual-stated (36f/38r psi) tire pressure, or is 40f/42r psi (or even higher since its not entirely gone away) normal? Rgds - jv | ||
| Screamer |
When new neck bearings are installed on an XB they may sometimes need to have the stem cap loosened and re-torqued (after the bike has been ridden several miles). Front isolator condition can also impact handling. | ||
| John_vreede |
Thanks Screamer, I'll loosen & retorque the s/head bearing to make sure. What should I look for to determine if the front isolator is worn? Was talking to a M/C mechanic friend who has forgotten more about bikes than I know and his immediate reaction was that I need to get a new set of tires on the bike asap, which he guaranteed would cure the excessive turn-in. Also said NZ has higher camber on roads than most anywhere else in the world and that we need to run 38fr/40r psi to compensate. I had a set of Metzeler Z8's fitted today and although they're not scrubbed in yet, the turn-in is neutral at 38fr/40r tire pressure - what I've been looking for. I'm not sure why the turn in has changed so much as the front tire was only ~half worn and the rear more than that, but not worn out and both had even wear over the whole surface - no flat spots, but it is what it is. It seems the last part of my quest for decent handling has been achieved. In order of importance the biggest improvements have come from: 1. Steering head bearings ($125NZ just parts) 2. New tires ($500NZ) 3. Tire pressure higher than std (maybe just an NZ thing) ($0) 4. Suspension setup ($0) 5. Rebuilt shock and forks ($1800NZ) Thanks to everyone who responded - jv | ||
| Screamer |
Front Isolator condition is a little tough to examine while on the bike. Supporting the engine and removing the vertical bolt may allow you to determine if there's obvious failure, but molding variations of the rubber may be misleading. Usually, a bad isolator has symptoms beyond just loose handling: excessive handlebar vibration when accelerating, horn rattle, and my clutch lever rattles when my isolator needs replacing. With the exception of a few periods of molding issues from the supplier, the isolators are pretty durable. But, wheelies with hard landings and stoppies impact isolator life. Good decision on replacing the tires. XB models seem sensitive to tire wear, and tires that look usable may cause a degradation in handling. |
