| Author | Message | ||
     Xbgraham |
Picked up a new 09 Uly xt last spring and it was fun at first ride. Initially I was pleased with the bike however I rode it a second time. When packing two up with loaded bags the rear suspension is really soft and was pogo'ish (okay thats not a word). Upping the compression damping and a bit more rebound slowed the shock action but the spring rate is still too soft. Does anyone know what the rate is so a stiffer spring can be installed? Also at full compression the bike makes an irritating growl/vibration through the seat. Would one of those spring loaded belt tension thingies be the answer to that issue? | ||
| Buellfan |
Are you at max preload? Verify that when you turn the preload adjuster that the spring preload actually changes (could be a leak in the adjuster). Don't be afraid to increase rebound as well as there is "cross-talk" on that circuit (more rebound gets you more low speed compression too). Lots of spring motion is usually from not enough rebound damping anyway. The vibration you are feeling is normal for a fully bottomed shock but you shouldn't be there often unless you are at or over GRAW (gross rear axle weigh). Check the owners manual for the max amount of weight you can haul and how much can go on the rear of the bike. When the shock sits on the compression bumper engine vibration is transmitted thought the shock body to the frame. The XT has a longer bottom out bumper, we couldn't get a triple rate spring in that length. I don't remember the spring rates anymore. | ||
| Xbgraham |
I did bump the preload but if the spring is too soft more preload isn't the fix (soft is soft, preload won't change the rate), I did add more rebound to slow the shock extending action. I didn't check the GRAW but hopefully we are under or I have to stay home while my wife rides  | ||
| Blake |
Preload is important to give the rear shock an adequate amount of compression travel. With a passenger on back, it likely needs to be maxed out or very close to it. The compression damping too will need to be turned way up. | ||
| Buellfan |
Don't forget you are dealing with a dual rate rear spring, more preload will get you into the second stiffer rate sooner in the travel. You aren't changing the spring rates but you are changing how much travel you have before the higher rate comes into play the sooner the better. Also more preload will reduce sag providing additional travel before touching the bumper. You are correct the spring rate is a compromise between 180 and 400 lbs. With ideal spring rates for GVWR the bike would be hardly ridable with one person and no bags because it would be way too stiff for that condition. There is more range of adjustment on the Buell suspensions than typical because we tried to make them work for most people but there are limits with how far you can go. The ends of the spectrum always give up performance for the sake of the majority. | ||
| Blake |
>>> more preload will get you into the second stiffer rate sooner in the travel. ... you are changing how much travel you have before the higher rate comes into play the sooner the better Preload only adjusts the ratio of compression travel to rebound travel. The spring is compressed the same amount no matter the preload. It can just compress more if the preload allows more compression travel, but it won't reach a higher rate sooner. | ||
| Xbgraham |
Hmmm, dual rate shock spring and linkless rear suspension, sounds like a pre 2011 KTM dirt bike. Thanks for the input but does anyone know what the actual rate(s) of the stock spring is? I think for my application I would drop the dual rate spring and go for a slightly stiffer single rate spring. Compression could be reduced for more compliant ride and rebound bumped up slightly to reduce "kicking". I thought the growling noise was normal but it is kind of disturbing. | ||
| Gringo |
looks like the right place to put this, cant remember where i found it but this guy, Sean Onipede, has done a great job of putting science into english, even if its weerid english. crud, cant seem to get the pdf compressed enough to download. anyway i have a really good writeup on suspension if anyone wants it pm me with an address (Message edited by gringo on February 17, 2011) | ||
| Netty2424 |
I was given a Firebolt Service Manual with my 2004 Lightning XB12s and need to adjust my suspension. Are the specs the same for both R and S model? And until I can get my hands on the correct manual, can someone shoot me the factory specs for 225lb rider for both front and rear suspension? thanks in advance... |
