83's XJ Fork Troubleshooting

Hello,
I am having issues with my front forks on my 83' XJ900RK. I drained the forks(dark black/silver fluid) and this time decided to up my fork oil weight to 15 instead of the 5 wt that's listed in the manual. The issue was my forks are bottoming out and bouncing so much its causing my speedometer needle to bounce with in 10mph. Also concerns for handling with the amount bounce i am chewing up. Does anyone have any suggestions, It also seems the longer i ride(after 45 min or so) that the oil must be heading up and the bounce gets worse along with the speedometer issue. I am about to try 30wt oil next....help please!

 

Have you taken the forks apart to inspect the inside? Draining dark/metalic oil is not a good sign. There are springs and check valves in there, they probably need cleaning. The fork main spring is getting weak with age and will need replacing with a heavy duty spring. Replacing them will greatly improve you handling , spring spacers will also help if you can't buy new springs yet.
30wt oil is to much, try dissambly and cleaning. Then refill with 15wt oil.

 

Hey mlew thanks for the reply. Do you know if the XJ900RK forks fit any other models? Incase i need to find a replacement tube, also i dont believe ill be able to fit a spacer in there. Also do you think the anti-dive will effect any of the issue i am experiencing? Thanks for your help.

 

I don't know if the 900 fork tube interchanges with any other bike. The tubes bon't usually wear out, they will get pitted from corrosion and cause leaks or they get bent from accidents. However the lower fork has a bushing that can wear out and cause a loose fit between the upper and lower tubes. If the fit is sloppy, look for another set of forks.
The anti-dive keep the forks from compressing durring braking, I don't think it would make the bike bounce.
Things I would do:
1 remove forks and dissamble. Inspect and replace worn out parts.
2 inspect and clean the anti-dive components
3 have front tire ballanced, check brake rotors for warpage
4 put it all back together, replace brake pads if needed, bleed brakes and anti-dive
I think you have several problems. Years of gunk built up in the forks that is preventing them from working. The front tire is out of ballance or the roors are warped.

 

Could this bushing wear cause a knocking sound? I have good bearings all around, but a persistant knocking.

cheers

 

I put a new set of progressive springs, 20w oil and a 1" pvc preloader.... Sorted ALL my fork issues

 

Yes mrblackstock that bushing could cause sounds from the forks. If it is extremely worn it can cause the forks to bind when compressing, thus making some kind of noise. The parts list say they are still available from Yamaha for around 20$. I have never put one in but it does not look hard to replace. If something is making noise in the forks when they compress then you need to fix it before it puts you on the ground. I hate to see someone hurt. Fork dissambly is not very hard nor does it require any special tools. Sometimes it can be difficult because of a stubborn bolt.

 

Do not attempt to do XJ900 forks without the service manual in hand. The oil locks in the anti-dive are delicate and you can easily damage them if you do it wrong. The locks are no longer available so if you damage one you're in a world of hurt.

 

Hey everyone.. just an update. Well it appears the previous owner was inside the forks and must of did some damage.. as the right tube cap was JB welded on, making it impossible to break loose to check the springs and disassemble. So its off to ebay and bone yards for replacement fork set. Old bikes sure do start to add up.. *sigh

 

uh-oh......................

dave

 

well found a replacement pair of forks on ebay..hopefully all is intact and works out..wish me luck