Modifications - Performance Discuss aftermarket and DIY performance modifications

900rr front end swap issues

Old 07-22-2011, 04:31 PM
  #1  
Junior Member
Squid
Thread Starter
 
Join Date: Mar 2011
Location: germansville, pa
Posts: 20
Dan C is on a distinguished road
900rr front end swap issues

Just fitted a 900rr front end on my 04 sh and under hard acceleration around 100 mph forks just fully extend and im getting alot of head shake.Handles great on twisties but in a straight line cant even wined out 4th gear without getting shakey! I know the 900 forks were a little shorter so my question is what do i have to do to remedy this? I have stock rear shock and i have tryed dropping triple clamp down fork tubes about an inch but no real improvement. Any ideas thanks.
Dan C is offline  
Old 07-22-2011, 08:28 PM
  #2  
Banned
MotoGP
 
Join Date: Aug 2007
Location: Lake View Terrace, CA
Posts: 5,942
8541Hawk will become famous soon enough
Well mikstr is who you need to talk with about geometry issue and set up with the 900 front end.

Though I would ask if you have checked the steering head bearings as they might be either too loose or over tightened.
8541Hawk is offline  
Old 07-23-2011, 02:30 AM
  #3  
Out of my mind, back in 5
MotoGP
 
Tweety's Avatar
 
Join Date: Nov 2006
Location: Skurup, Sweden
Posts: 6,109
Tweety is on a distinguished road
Start with the basics... Head bearings, tire wear (ridges) & pressure (both ends), but other than that I have no specific info...

A question though... You said you dropped the clamp down the tubes to alliviate the problem... Isn't that backwards? The fork tubes are shorter than stock, creating a steeper angle... So going even shorter would make the bike even more nervous... I'd say try it with the tubes as far down as possible (top of tube flush) making the fork as long as possible...
Tweety is offline  
Old 07-23-2011, 03:21 AM
  #4  
Senior Member
SuperSport
 
Join Date: May 2008
Location: Central Fl.
Posts: 530
PUSHrod is on a distinguished road
I have 900 forks on mine.

The phrase; 'hard acceleration around 100 mph forks just fully extend and getting a lot of head shake' caught my eye. My bike is planted solid on Duda Farms road giggling past that speed and more. Extending the fork tubes above the triple tree quickens the steering response but also destabilizes it. My forks are set dead even with the tops of the triple tree. No wobble issues what so ever.

Reassure that the basics are correct. Forking fluid, bearings, tires front and rear alignment. You know the drill.

Check that the spring tension is set for your body weight, at 175# body weight I'm set to three lines showing. And then see that rebound damping is dialed in and your body ergos are compliant. If you sit up and pull against the grips the front end will get light, if you move forward and tuck in out of the wind, you weight the front end and stabilize it.

Go forth, now, and chase some ducks.
PUSHrod is offline  
Old 07-23-2011, 04:30 AM
  #5  
Senior Member
MotoGP
 
mikstr's Avatar
 
Join Date: Apr 2005
Location: Montreal
Posts: 5,561
mikstr is on a distinguished road
I agree with what's been posted here: forks flush with triples and check from there (tire condition and pressure, wheel alignment, steering head bearings,....) Also, have you the forks been modified at all? I am running a Gold Valve kit and proper springs FWIW.
mikstr is offline  
Old 07-23-2011, 06:55 AM
  #6  
Senior Member
SuperBike
 
JamieDaugherty's Avatar
 
Join Date: Aug 2005
Location: Fort Wayne, IN
Posts: 1,836
JamieDaugherty is an unknown quantity at this point
Shorter forks shouldn't cause that problem, I'd be looking elsewhere for the culprit. I agree, I'm wondering if there is something wrong inside the forks that's causing you the problems.

Head shake at speed is pretty weird. I'd start with making sure your mechanical bits are in order before going any further. Let us know what you find out!
JamieDaugherty is offline  
Old 07-23-2011, 12:14 PM
  #7  
Junior Member
Squid
Thread Starter
 
Join Date: Mar 2011
Location: germansville, pa
Posts: 20
Dan C is on a distinguished road
What would you charge to do a full rebuild on stock sh forks and what would it be for 900rr forks? I also belive its more of a mechanical issue at this point.
Dan C is offline  
Old 07-23-2011, 12:49 PM
  #8  
Banned
MotoGP
 
Join Date: Aug 2007
Location: Lake View Terrace, CA
Posts: 5,942
8541Hawk will become famous soon enough
What is the oil level set at in the forks? Did you change the fluid or at least check the level before you installed them?

Or the real question, do the forks have any fluid in them?
8541Hawk is offline  
Old 07-23-2011, 05:17 PM
  #9  
Junior Member
Squid
Thread Starter
 
Join Date: Mar 2011
Location: germansville, pa
Posts: 20
Dan C is on a distinguished road
Yes the forks have proper amount of oil. I rode about two weeks with fork tops flush with top triple, just tryed dropping front an inch to see effects on handling. No change for the better tho. And head bearings are tightened properly as well.Front tire good condition too.
Dan C is offline  
Old 07-24-2011, 09:05 AM
  #10  
Senior Member
SuperBike
 
JamieDaugherty's Avatar
 
Join Date: Aug 2005
Location: Fort Wayne, IN
Posts: 1,836
JamieDaugherty is an unknown quantity at this point
Originally Posted by Dan C View Post
What would you charge to do a full rebuild on stock sh forks and what would it be for 900rr forks? I also belive its more of a mechanical issue at this point.
The price is the same for either set of forks. Shoot me an e-mail and I can give you a current quote. Thanks!
JamieDaugherty is offline  
Old 07-25-2011, 11:18 AM
  #11  
Senior Member
Back Marker
 
Join Date: Nov 2008
Posts: 129
MC Leather is on a distinguished road
Try changing you body position. Slide way back in the seat or way forward. If one of the positions improves the handling make adjustments to the bike so the bikes weight is more like the position you liked. If the bike was happy with you way back on the seat, slide the forks down and maybe decrease rear ride height or preload. If it was happy with you way up on the seat do the opposite.
MC Leather is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
thedeatons
Technical Discussion
5
08-02-2013 04:40 PM
scooter72
Modifications - Performance
13
12-30-2010 07:55 PM
Letsrideinsc
Modifications - Performance
1
03-01-2007 08:12 PM
Letsrideinsc
Modifications - Performance
9
11-08-2006 08:29 PM
selztoad
Classifieds
7
10-01-2006 10:15 AM


Thread Tools
Search this Thread
Quick Reply: 900rr front end swap issues


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.