Sunday 30 June 2019

FJ Fork Seal Replacement

I recently noticed a small leak on one of the FJ's forks. The bike's MOT (annual safety check) was due so I decided to replace the seal. This is fairly simple job and one I've done in the past. A couple of special tools are needed though. From my records I see that the seal was last replaced 8 years and 55,000 miles ago so not bad.   
The leak is very slight but I guess it won't get better

Tip - loosen the fork top bolt before removing the fork otherwise it's tricky to get off

Fork removed

Drain oil

This is the dust seal

The metal inside the seal has corroded and burst the seal. I don't think this caused the leak but it's not good because flakes of rust could score the fork leg.

I got a pair of oil seal & a pair of dust seals

To strip the forks a special tool is needed. It's a long bar with a 27mm hex head. I made this one years ago.

It goes down the fork to allow the damper screw to be removed

The fork then comes apart

There is some pitting on the fork leg

The pits are outwith the stroke of the seal (otherwise the tube would be scrap) I buff them smooth to avoid damaging the new seal when fitting.

New seal installed

To push the seal into place I made this tool a long time ago

New oil

The dust seal on the other fork was a bit crusty so I replaced it as well

All done. The fork protectors are after market. I don't know if they do any good but why not?


  1. Hi Stuart, as a fellow FJ owner I have had to change fork seals at about 50,000 but they failed again within 10,000 on investigation the Patten seals had failed I fitted Yamaha genuine seals and they seem to be good so far, seems its a known issue according to the FJ owners Club, any way keep riding and blogging it keeps me amused. If you are down in reiver country again give me a shout.

    1. The dust & oil seals were cheapies from eBay but hopefully they'll last.

      Glad you like my Blog.