The Sportster and Buell Motorcycle Forum - The XLFORUM®
 

Go Back   The Sportster and Buell Motorcycle Forum - The XLFORUM® > SPORTSTER MOTORCYCLE FORUM > Sportster Motorcycle Suspension, Frame, Forks, Handlebars, Fuel Tank, Oil Tank, Fenders
XLF Blogs XLF Arcade XLF Disclaimer/Privacy Statement/Terms Of Use

Notices

Sportster Motorcycle Suspension, Frame, Forks, Handlebars, Fuel Tank, Oil Tank, Fenders Discuss Sportster Motorcycle Suspension, Frame, Forks, Handlebars, Fuel Tank, Oil Tank, Fenders problems, advice, and/or how tos.

Active Threads
0 Case bolts and cyl base bolt torque
Last Post: bustert
Posted On: 6 Minutes Ago
Replies: 20
Views: 483
0 Food porn
Last Post: Stairman
Posted On: 11 Minutes Ago
Replies: 2,500
Views: 578,567
0 Official XL Forum Random Image Thread (NO NUDITY!)
Last Post: maltesefalcon
Posted On: 16 Minutes Ago
Replies: 52,033
Views: 8,757,803
0 ‘21 Forty-Eight Stage 1 Hi Flow A/C backplate gasket issue
Last Post: Ludwig von Buzzthoven
Posted On: 21 Minutes Ago
Replies: 5
Views: 138
0 video & pics
Last Post: cal43
Posted On: 22 Minutes Ago
Replies: 434
Views: 44,520
0 Keep & Kill
Last Post: Graywolf
Posted On: 52 Minutes Ago
Replies: 24,682
Views: 1,455,385
0 ....1
Last Post: Graywolf
Posted On: 55 Minutes Ago
Replies: 6,269
Views: 379,593
0 easy rider homage peter fonda ironhead
Last Post: Steve9
Posted On: 56 Minutes Ago
Replies: 15
Views: 1,225
0 Hottie of the day, no nudity.
Last Post: cal43
Posted On: 1 Hour Ago
Replies: 32,189
Views: 3,745,730
0 This is gonna hurt.
Last Post: cal43
Posted On: 1 Hour Ago
Replies: 8,910
Views: 2,075,508
0 Carb ???
Last Post: Iron Mike
Posted On: 1 Hour Ago
Replies: 219
Views: 48,997
0 Hot Chicks on Hot Bikes
Last Post: cal43
Posted On: 2 Hours Ago
Replies: 12,528
Views: 2,916,765
0 It's Glamazon's Birthday!
Last Post: Glamazon
Posted On: 4 Hours Ago
Replies: 10
Views: 122
0 Deeded Electrical
Last Post: Ark OB
Posted On: 7 Hours Ago
Replies: 11
Views: 522
0 Dragging clutch
Last Post: Ark OB
Posted On: 7 Hours Ago
Replies: 22
Views: 1,558
0 What oil temp do you run
Last Post: cal43
Posted On: 7 Hours Ago
Replies: 136
Views: 31,883
0 Peanut, 3.3 or 4.5 gas tank ?
Last Post: IXL2Relax
Posted On: 8 Hours Ago
Replies: 261
Views: 83,212
0 need help with 68 XLH
Last Post: andy2175m4
Posted On: 9 Hours Ago
Replies: 18
Views: 1,179
0 Finally some nice weather in the northeast!
Last Post: BKB
Posted On: 11 Hours Ago
Replies: 60
Views: 7,102
0 Mainshaft Oil Seal Leak
Last Post: Gold Member
Posted On: 11 Hours Ago
Replies: 34
Views: 8,862
0 Riding Around Smoky Yellowstone National Park in 2021
Last Post: sportsterpaul
Posted On: 12 Hours Ago
Replies: 9
Views: 84
0 Anyone go racing last weekend?
Last Post: mac93
Posted On: 13 Hours Ago
Replies: 3,408
Views: 385,431
0 For Sale 2003 XL883C 1200 Conversion
Last Post: webrehm
Posted On: 13 Hours Ago
Replies: 3
Views: 334
0 1983 Roadster
Last Post: RicThompson
Posted On: 14 Hours Ago
Replies: 28
Views: 1,114
3 still not a drop!!! 1979 1000xlh
Last Post: Ferrous Head
Posted On: 15 Hours Ago
Replies: 8
Views: 225
0 This week on Craig's list
Last Post: Fivecats
Posted On: 17 Hours Ago
Replies: 5,371
Views: 882,412
0 Automotive Motor Oil In Sportster
Last Post: Hippysmack
Posted On: 17 Hours Ago
Replies: 52
Views: 1,850
0 Iree's late night cafe
Last Post: Stairman
Posted On: 20 Hours Ago
Replies: 2,134
Views: 359,399
0 What song do you have stuck in your head?
Last Post: rokytnji
Posted On: 22 Hours Ago
Replies: 2,420
Views: 257,941
0 2021 Iron Butt Rally
Last Post: ChinCactus
Posted On: 22 Hours Ago
Replies: 133
Views: 14,097
More...
Members Birthdays
Reply
 
Share Thread Tools Display Modes
  #11  
Old 16th September 2007
XLXR's Avatar
XLXR XLXR is offline
XL FORUM LIFE MEMBER
 
Join Date: Aug 2006
Posts: 12,228
Sportster/Buell Model: XL1200 R
Sportster/Buell Year: 2006
Reputation: 932072
XLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond repute
Default

cbnightster - The 12 inch long 412's with a 75/120 spring (I think that is standard) is probably a good choice for your weight. That should raise the rear up about 1 inch for a total travel of 2 inches.

Correction: I double checked the Progressive web site, the 12 inch 412's have a 90/130 spring, the 12.5 inch long to get the 75/120.

To raise the forks, you will have to figure out if HD lowered them with extra rebound springs. If that is true, you will have to take a 1 inch of rebound spring to allow the forks to extend 1 inch. Trying to cram in a heavier main spring or adding more perload will only pull against the rebound springs and not give you the height increase you are looking for. Judging by the feed back on the forum, the standard Progressive spring is better that the stock Roadster fork spring. So far Hoghead has provided the only report I have read of the Progressive fork spring in a Nightster, but the guy still needs to do some fine tuning to get it right.

Taking the forks apart to change the rebound springs in not too hard IF you have the manual and better than average mechanical skills. There are no manuals on line, unless some one posts a copy of a page. If I remember correctly, the only special tools needed are snap ring pliers, and a seal driver. I used pvc fittings as a seal driver. A turkey baster with a long hard copper tube on the end can be used to measure and set fork fluid levels.

One of the problems with short shocks and forks that Whittlebeast and I have found out is that the short travel of the shocks and forks do not allow the spring enough distance to fully transition from the low rate to the high rate. 2 inches of travel is better that 1 inch, but still won't be as good as 3 or 4 inches. So the compromise is ride quality vs style of a lowered look. If you want to get really good suspension, I would recommend raising the suspension all the way.

Another option to consider is using 13 inch shocks combined with 1 inch lowering blocks. I am thinking this may be the only way for a 140 lb rider to get a good ride because the longer shocks have lower spring rates the lighter riders need.

I did not actually measure, but the Nightster forks have about 2 inches of travel and the Roadster have 4 inches of travel.

As to fine tuning, since you are going where no Nightster rider has ever gone before, I'll be happy to offer my services of free advice. But expect to do quite a bit of fine tuning.
__________________
Former Ricor test rider for IAS Shocks, Intiminators and Vibranators. Works Dual Rate fork springs, fork brace, Avon Venom X tires, loosen drive belt, and set frame rails level to floor. See "7 Pages of Suspension" thread in the Suspension Sticky Index. It's official, I am now in the "I've forgotten more than I remember club."

Last edited by XLXR; 18th September 2007 at 04:49..
Reply With Quote
  #12  
Old 17th September 2007
cbnightster's Avatar
cbnightster cbnightster is offline
Master Mechanic
 
Join Date: Jul 2007
Location: Lettuce Capital of the Universe
Posts: 247
Sportster/Buell Model: 1200N
Sportster/Buell Year: 2007
Reputation: 189
cbnightster is on a distinguished roadcbnightster is on a distinguished road
Default

The 1200N shares the same fork setup as the 883L with the exception of a spacer ring between the damper spring and damper tube which is unique to the 1200N. The 1200L only shares the slider tube with the 1200N and 883L ( some components fit all). The 1200L shares the same fork set up as the 1200R with the exception of the damper tube and fork spring which is unique to the 1200L. In the exploded view the 1200N and 883L use a collar (pre-load spacer) the others do not.
I am assuming (dangerous) the slider housings are the same for all except the the rt side on the R, the N has a different p/n, but I assume it is because it is black as well as the 883R which is matte black.

In order to convert to the 1200R fork set up I would need to replace:
Fork spring (2) 45376-04 (Replace with progressive)
Slider tube (2) 45395-04
Damper tube ring (2) 45469-90
Damper tube (2) 45925-04
Seals
All other components common to all.

Down side to the conversion is that the fork gaiters will no longer fit properly, I guess I could find something that may work?

I agree that most of the problem with the N (and 883L) suspension is due to a lack of travel, so trying to tune it is very challenging as there are not as many options as there is with the other models.

At this point I am going to install the 412 12" rear shocks and then progressive front springs, at minimum it will be an improvement over stock and any improvement will be well worth it!

CB
__________________
"Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety". Ben Franklin
"When the people fear their government, there is tyranny; when the government fears the people, there is liberty". Thomas Jefferson
Reply With Quote
  #13  
Old 17th September 2007
XLXR's Avatar
XLXR XLXR is offline
XL FORUM LIFE MEMBER
 
Join Date: Aug 2006
Posts: 12,228
Sportster/Buell Model: XL1200 R
Sportster/Buell Year: 2006
Reputation: 932072
XLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond repute
Default

Good work. Good information.

However, I don't think you need to actually convert the Nightster forks to Roadster forks to get an increase in travel. I only have the 06 manual, so I can't be sure. But I think what you are refering to as the "damper spring", in my book is called the "rebound spring." It is a spring about 1 inch long that keeps the fork tubes from hitting metal to metal when the forks fully extend.

I think the "spacer ring" does the same thing that lowering springs do in the after market fork lowering kits. It basically adds length to the rebound spring to lower the forks by pulling the upper fork down into the lower fork. It is hard to explain, but if you take apart the forks, it is easy to understand.

So, I think if you simply take out the "spacer ring", the forks will raise by whatever its length is. If the spacer is 2 inches long and you only want to raise the forks 1 inch, replace the spacer with a 1 inch long rebound spring.

Another question that needs to be answered is if the damper tubes are the same length, or is the difference due to the holes for compression and rebound dampening being different?

Make sense?

EDIT:Since looking at 06 and 07 fork parts manual, I have no idea if it is possible to convert Nightster forks to Roadster forks, or how much you can increase travel in the Nightster forks. If you try this, you will be the first that I know of to try.

Last edited by XLXR; 18th September 2007 at 04:56..
Reply With Quote
  #14  
Old 17th September 2007
sportytrace's Avatar
sportytrace sportytrace is offline
OzChick
 
Join Date: Jun 2007
Location: Mt Tamborine, QLD, Oz.
Posts: 3,456
Sportster/Buell Model: XL 1200N
Sportster/Buell Year: 08
Other Motorcycle Model: Triumph Bobber
Other Motorcycle Year: 2017
Blog Entries: 61
Reputation: 12256720
sportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond repute
Default

It would be interesting to know what the setup is on the UK and European 1200N too, as they are higher; I'm assuming both front and back??!! Which fork spring are they using I wonder? Have they left out the preload spacer?

Quote:
Originally Posted by cbnightster View Post
The 1200N shares the same fork setup as the 883L with the exception of a spacer ring between the damper spring and damper tube which is unique to the 1200N. The 1200L only shares the slider tube with the 1200N and 883L ( some components fit all). The 1200L shares the same fork set up as the 1200R with the exception of the damper tube and fork spring which is unique to the 1200L. In the exploded view the 1200N and 883L use a collar (pre-load spacer) the others do not.
I am assuming (dangerous) the slider housings are the same for all except the the rt side on the R, the N has a different p/n, but I assume it is because it is black as well as the 883R which is matte black.

In order to convert to the 1200R fork set up I would need to replace:
Fork spring (2) 45376-04 (Replace with progressive)
Slider tube (2) 45395-04
Damper tube ring (2) 45469-90
Damper tube (2) 45925-04
Seals
All other components common to all.

Down side to the conversion is that the fork gaiters will no longer fit properly, I guess I could find something that may work?

I agree that most of the problem with the N (and 883L) suspension is due to a lack of travel, so trying to tune it is very challenging as there are not as many options as there is with the other models.

At this point I am going to install the 412 12" rear shocks and then progressive front springs, at minimum it will be an improvement over stock and any improvement will be well worth it!

CB
__________________
Sportytrace ~ "Orange is the happiest color"
OzChick ~ Riding 90"Nyx DownUnder ~My Photography Website: www.photobytrace.com

Work/Life Balance? Just work more at Living!
Nyx: 08 XLN~ 90" Dyno Results; 90" of Street-based FUN coming downunder; My six year refresh adventure
TBob: 2017 Triumph Bobber; Making a Decision on a New Bike
Muse: 1982 Honda CBX Shed Find
Photography: My take on the world
Reply With Quote
  #15  
Old 17th September 2007
XLXR's Avatar
XLXR XLXR is offline
XL FORUM LIFE MEMBER
 
Join Date: Aug 2006
Posts: 12,228
Sportster/Buell Model: XL1200 R
Sportster/Buell Year: 2006
Reputation: 932072
XLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond repute
Default

Quote:
It would be interesting to know what the setup is on the UK and European 1200N too, as they are higher; I'm assuming both front and back??!! Which fork spring are they using I wonder? Have they left out the preload spacer?
Harley doesn't tell us how any bikes are set up. If you want to improve your suspension, it will be trial and error like every one else. Understanding what I have been describing in this and my other suspension threads will be a good start. I will keep everyone posted about the progress we make with Road Chicks Nightster. The next question I ask people who want to improve their suspension is ... how much work do you want to do? If you describe how your bike rides, I will try to explain why it rides that way and what you can do to improve it. I am off work for the next week because of surgery, so I have nothing better to do than sit here and type.

If you want to measure suspension sag of the forks and shocks and post the results, maybe someone else will do the same for a US bike.

Jack the bike up so both tires are off the ground. For the rear, measure the vertical distance up from the axle to some point on the chrome side piece on the fender. For the front, pick one point on the upper fork tube (EDIT: like the top of the cap) and another on the lower fork tube. Using a piece of tape to mark the points is the easiest way.

Lower the bike to the ground, have some one hold the bike up vertical, off the kick stand. Measure the same points and subtract the short measurement from the long one. That is how much the bike's weight compresses the springs. That is called bike sag or unloaded (no rider) sag. (EDIT: If you sit gently on the bike the forks may not compress at all, you may have to bounce the forks to get them to compress, just be consistent. Push them down and let them slowly come up, use that point to measure. There is so much internal friction (stiction) in these forks it is hard to get them to stop at the same point everytime.

Since the bikes are all the same weight, if the bike sag measurements are different, the springs will also be different. Well, not quite. The length of the preload spacer can affect bike sag, so everyone will need to set the shock sag to the lowest setting before taking the measurements. If two different bikes have the same preload spacer and the same spring, the bike sag measurements will be the same.

Last edited by XLXR; 18th September 2007 at 05:03..
Reply With Quote
  #16  
Old 17th September 2007
sportytrace's Avatar
sportytrace sportytrace is offline
OzChick
 
Join Date: Jun 2007
Location: Mt Tamborine, QLD, Oz.
Posts: 3,456
Sportster/Buell Model: XL 1200N
Sportster/Buell Year: 08
Other Motorcycle Model: Triumph Bobber
Other Motorcycle Year: 2017
Blog Entries: 61
Reputation: 12256720
sportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond repute
Default

Hi XLXR, I actually have the same setup as the US bike. The Oz bikes have the 11" rear suspension and lowered fork springs, same as RCs. I was just curious as to how the UK / Euro bikes were riding, and was hoping one of them would pipe in. I suspect that their bikes may be riding somewhat better and as such nobody has had the need/desire to look into what's actually on the bike yet. But as CBNightster is trying to lift his nightster up; I just wanted to alert him to the thought that the parts that were used in the forks of the Euro bikes may help him solve his queries. Don't know if anyone has access to the '08 parts manual (hasn't made it's way to Australia yet) to know what the differences are in terms of parts and part numbers etc.

I've been following what you are doing with Rene's bike very closely, and am really appreciative that the three of you are sharing so much and posting all the findings and trials and errors, it'll certainly help me to make a more informed choice on my suspension setup and to help me enjoy my bike even more. So thank you! Hope you a speedy recovery and are out riding again soon.
Cheers
Trace
Reply With Quote
  #17  
Old 17th September 2007
Screw Loose Dan's Avatar
Screw Loose Dan Screw Loose Dan is offline
I think I like Sportsters
 
Join Date: Oct 2006
Location: Collegeville, PA
Posts: 7,108
Sportster/Buell Model: 883L (sorta) & a 1200R
Sportster/Buell Year: 2007
Sportster/Buell Model #2: 1200CX
Sportster/Buell Year #2: 2016
Other Motorcycle Model: XR1200X
Other Motorcycle Year: 2012
Reputation: 3389903
Screw Loose Dan has a reputation beyond reputeScrew Loose Dan has a reputation beyond reputeScrew Loose Dan has a reputation beyond reputeScrew Loose Dan has a reputation beyond reputeScrew Loose Dan has a reputation beyond reputeScrew Loose Dan has a reputation beyond reputeScrew Loose Dan has a reputation beyond reputeScrew Loose Dan has a reputation beyond reputeScrew Loose Dan has a reputation beyond reputeScrew Loose Dan has a reputation beyond reputeScrew Loose Dan has a reputation beyond repute
Default

Quote:
Originally Posted by XLXR View Post
Hoghead - great report, thanks. Your report of the Progressive spring in a Nightster is the first one I have read.
XLXR - Here's a few threads/discussions on the Nightster/883L fork springs you might be interested in:

http://www.xlforum.net/vbportal/foru...ad.php?t=51825

http://www.xlforum.net/vbportal/foru...ad.php?t=64875

http://www.xlforum.net/vbportal/foru...ad.php?t=51157

http://www.xlforum.net/vbportal/foru...ad.php?t=70885
__________________
Screw Loose Dan
Current fleet:
2007 - 1200R (Orange bike)
2012 - XR1200X (XR)
2016 - 1200CX Roadster (new one)
2007 - 883L/90" -current project - (Black bike)
Reply With Quote
  #18  
Old 17th September 2007
ColinB ColinB is offline
Senior Master Custom Bike Builder
 
Join Date: May 2007
Posts: 3,745
Sportster/Buell Model: 883R
Sportster/Buell Year: 2007
Reputation: 1721574
ColinB has a reputation beyond reputeColinB has a reputation beyond reputeColinB has a reputation beyond reputeColinB has a reputation beyond reputeColinB has a reputation beyond reputeColinB has a reputation beyond reputeColinB has a reputation beyond reputeColinB has a reputation beyond reputeColinB has a reputation beyond reputeColinB has a reputation beyond reputeColinB has a reputation beyond repute
Default

I've been following these threads closely trying to get my 2007 883R riding as well as possible. I'm about 144lbs in full riding gear - so I'm in trouble already!!

Mines a UK bike and this is what I've found so far.

The rear shocks are 13" and on their lowest pre-load position they sag to 11 7/8" with me on it - so giving a sag of just over 1".

The forks have a fully extended length of 5 1/2" from the top of the slider to the bottom of the lower tripple clamp, and with me on it they sag to 3" - giving a sag of 2 1/2". Far too much! I took the top off one of the fork tubes - and there's about 3" of spring sticking up with no spacer at all!! I've dropped the front of the bike down the forks by 3/4" to get the front of the frame rails 2 1/2" of the ground and the rear 2 1/4". The bike handles OK but the lack of damping and rubbish forks are very obvious.

I've ordered some 12 1/2" Progressive Suspension 412s as they have a spring rate of 75/120, while anything lower goes up to 90/130. I'm thinking that the sag on these will lower me with a decent amount of sag AND give a better ride quality for my weight than shorter, harder shocks.

When they arrive I'll fit them and let you know what I think with some measurements to back it up. Then I'll try and sort out the forks when I know my ground clearence.

Hope this helps the discussion.
Colin
Reply With Quote
  #19  
Old 17th September 2007
XLXR's Avatar
XLXR XLXR is offline
XL FORUM LIFE MEMBER
 
Join Date: Aug 2006
Posts: 12,228
Sportster/Buell Model: XL1200 R
Sportster/Buell Year: 2006
Reputation: 932072
XLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond reputeXLXR has a reputation beyond repute
Default

drsctang - Thanks for the info and the links. I read through them quickly.

ColinB - Congratulations, now that is an excellant report. Stating both your weight and the spring rate of the forks or shocks is MANDATORY.

PLEASE GUYS, ALWAYS STATE YOU WEIGHT AND SPRING RATES, EDIT: AND PRELOAD SETTING, otherwise your impressions as to ride quality are meaningless.

I was able to compare the parts listings for 06 and 07 bikes, I assume US bikes. It does not appear Harley used extra rebound springs (as called in the service manual, but called spring slider in the parts manual) to lower the forks of Lows and Nightsters. Something else is different, but I cannot tell what it is. So I have no idea if the forks of Lows and Nighsters can be raised or how much they can be raised. Someone will have to totally disassemble their forks to determine that.

One of the problems is Harley does not tell us what the spring rates are for the different springs used. In addition, the 07 Nightster had such a big preload spacer that put so much force on the spring, even knowing the free spring rate would not help much. I can tell you this, the standard FORK spring in a 07 Nightster is too light for a 180 lb rider, because the forks bottom out too easily, even with a 140 rider.

A word about spring rates. A straight rate (non-progressive) spring is rated in how many lbs of weight it takes to compress the spring 1 inch. For example, if the spring was a straight rate of 100 lbs/ inch, 100 lbs would compress the spring 1 inch, 200 lbs would compress the spring 2 inches, and so on untill the forks bottomed out at the end of their travel.

A progressive rate spring is rated by stating the initial spring rate and the final spring rate. Using shock spring rates as an example, a 75/120 lb spring indicates 75 lbs will compress the spring the first inch, but somewhere in the travel the spring rate increases to the point where 120 lbs are required to compress the spring one inch. 75 is the initial rate, this provides a smooth ride over small bumps in the road. The 120 final rate means the spring is getting much stiffer towards the end of the travel and is much better at preventing bottoming out. A 75 straight rate spring would be too light and bottom out, and a 120 straight rate spring would ride too stiff to be comfortable.

The big question is how far down the travel does the spring transition from a 75 to 120 lb rate. That is especially important to know because if you have short travel suspenion, your spring may not even fully transition to the heavier 120 lb rate, and you will bottom out all the time.

Whittlebeast and I are in constant communication about all aspects of bike set up. His has a better shop than mine. Road Chick sent him her stock shocks off 07 Nighterster, and he found the shock travel is so short, the springs are not transitioning to the higher rate. I suspect the same is happening with the forks.

A few words about fork oil. Changing to a heavier fork oil slows the speed at which the bottom fork tube can move up (compression) and down (rebound). It slows the fork movement throughout the entire range of travel. The slower the forks move, the worse the ability of the tire to track bumps in the road will be. I know two people who tried the Harley SE heavy duty fork oil. Road Chick in her 07 Nightster, it made things worse and she took it out. The other guy has a 07 Roadster. I rode his bike, his forks were mush compared to mine. In addition, while riding along side of him on the highway, I could occassionally see light under the tire because it was in the air, not in contact with the road. This illustrates why using a heavier fork oil to compensate for a weak spring is not a good idea.

It is much better to add extra oil to the forks, about 1 oz for Lows and Nightsters, 2 oz for Roadsters, which will prevent bottoming.

Got to go, heading over to a buddies and supervise him changing his suspension, more to follow.

Last edited by XLXR; 19th September 2007 at 06:55..
Reply With Quote
  #20  
Old 18th September 2007
sportytrace's Avatar
sportytrace sportytrace is offline
OzChick
 
Join Date: Jun 2007
Location: Mt Tamborine, QLD, Oz.
Posts: 3,456
Sportster/Buell Model: XL 1200N
Sportster/Buell Year: 08
Other Motorcycle Model: Triumph Bobber
Other Motorcycle Year: 2017
Blog Entries: 61
Reputation: 12256720
sportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond reputesportytrace has a reputation beyond repute
Default

Quote:
Originally Posted by ColinB View Post
Mines a UK bike and this is what I've found so far.
The rear shocks are 13" and on their lowest pre-load position they sag to 11 7/8" with me on it - so giving a sag of just over 1".
The forks have a fully extended length of 5 1/2" from the top of the slider to the bottom of the lower tripple clamp, and with me on it they sag to 3" - giving a sag of 2 1/2". Far too much! I took the top off one of the fork tubes - and there's about 3" of spring sticking up with no spacer at all!! I've dropped the front of the bike down the forks by 3/4" to get the front of the frame rails 2 1/2" of the ground and the rear 2 1/4". The bike handles OK but the lack of damping and rubbish forks are very obvious.
Thanks Colin for piping in! So HD didn't get the Euro suspension much better it seems. Good luck with sorting out your forks.
Reply With Quote
Reply

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



All times are GMT +1. The time now is 14:41.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
XL Forum® - Linson Media LLC