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.

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. ;)

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...

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.

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.

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!

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.

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?

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.

The price is the same for either set of forks. Shoot me an e-mail and I can give you a current quote. Thanks!

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.