Hi,
I'm going to be rebuilding my front fork on an '82 750 seca because of a leaky oil seal and remembered seeing a description in an old thread, but wasn't able to find it again. I was wondering if I should be replacing the dust seal also, and does anyone have any words of wisdom or little tricks i should know about. Any help would be much appreciated.
Thanks
Mark

You may want to check out this link should give some insight on how to change the fork seals. http://members.fortunecity.com/brevans/tech/forks.html
A good place to buy a set of new fork seals check out http://www.denniskirk.com

Definately change the sust seals. They are cheap and most likely contributed to your current seals leaking. I highly recommend using the Yamaha fork seals. I bought a set of the "Leak Proof" seals and didn't like them. The Yamaha seals are far better. I had trouble getting the old seals out at first and then figured a way to retrieve them. I went to Auto Zone and rented a slide hammer. The small 3 bladed attachment worked great. It grabbed the inside of the seal and with 2 hits they were out. Best part, the tool is a free rental at Auto Zone. A piece of PVC pipe worked well as a drift for seating the seals.
Make sure you replace the wire clips also. They usually gather rust after this many years and can fail at any time. My forks leaked sue to the dust seals letting water through and the rust off of the wire clips degraded the fork seals.
Used 15 wt. fork oil and have never regretted it. Of course I am down in the humid south. May not be what you want in New England or Canada. Also to grip the inner 19mm hex head a special is needed. I have been told that reversing a spark plug socket will work. The hex end is the same size so just add it to the end of 2 long extensions and go fot it! Once that is loose if the lower leg doesn't pull off you may have to gently heat it to seperate it from the stanchion. Feel free to ask questions!

If you want to save some money on fork oil try automatic transmision fluid. It works for me.

Thanks for the help, i guess i'll go with yamaha oil seals. this will be a good winter project. Thanks again
Mark

I recently replaced my fork seals without taking the forks apart:

Remove the dust seal and any circlips or washers holding in the old oil seal.
Pop the top cap and remove the fork spring.
With the fork not quite compressed (leave about an inch of travel), fill the fork tube right up with oil. Don't leave any air space.
Re-install the top cap.
Compress the fork using a bar clamp. Leave it alone.
Since liquids can't be compressed, in a couple of hours the fork oil will force the old seal out of its hole.
Dump the old oil, install the new seal, put everything back together. I used an ABS pipe that just fit over the fork tube to drive the new seal home.

You won't have to remove any bolts at the bottom of the forks or replace any worn or mangled sliders. A lot easier than taking your forks apart if all you need to do is replace a leaking seal.

Good Luck,

Shil

"Once that is loose if the lower leg doesn't pull off you may have to gently heat it to seperate it from the stanchion. Feel free to ask questions! "

Need to correct myself on this point. They should come right apart , the heating was for replacement of the bushing. You won't be doing that. Sorry 'bout that!

You might want to look at replacing the fork bushes if you're overhauling the forks
2 reasons for this:
1. If they are worn, the seals will inevitably leak again.
2. If they are worn, they will make the front end feel sloppy.
There's 2 in each fork leg - one on the bottom of the slider and one in the top of the fork leg (under the seal). They are made of copper or similar soft metal (so they don't scratch the forks) and are designed to wear. Here in Australia, they are not very expensive to buy from Yamaha.
Also, you can split the forks fairly easily by keeping the springs in and undoing the bottom damping rod bolt with an air impact wrench. This way the fork spring tension holds the damping rod in place - no need for Mr Yamaha's special tool to hold the rod. Then take off the dust seals and any circlips and pull the forks apart. Easy.
I had an old GS Suzuki that kept blowing fork seals only in one leg and it ended up being the bushes. After replacing them, the leak disappeared and the front end handled better, too.

i think I will be replacing the bushings also, might as well if it's all apart. i might also put in progressive springs while i'm at it. Hillsy when you say "split the forks fairly easily by keeping the springs in and undoing the bottom damping rod bolt with an air impact wrench" do you mean just lossening it? I would think undoing the bolt all the way would result in the two tubes flying apart. Anyway, thanks for all the help.
Mark

Undoing the bolt on the bottom of the fork will not make the forks spring apart. All the springs are inside the slider (top section). The damper rod sticks out of the end of the slider inside the bottom fork leg - and this is what the bolt goes into to hold the 2 parts of the fork together.
If you clamp the caliper mounts on the bottom fork leg in a vice so the forks are horizontal you can work on them easily, too. I use a couple of short lengths of aluminium angle as soft jaws in my vice so they dont scratch the forks. With the bottom bolt undone and the dust covers and circlips out, you may still need to use a bit of force to pull the slider out of the fork leg (the bush on the slider will either pull out the seal or have to squeeze past it). Dont be afraid to force them.
If you're going to change / take out your springs as well, make sure you loosen the fork caps (half a turn) while they are still on the bike. Makes it easier to undo them later when you disassemble them on the workbench / in the vice.
Lay all the parts out in order on your workbench and dont mix up the parts between the forks. It's a good idea to have a workshop manual to refer to (which should have an exploded parts view), because the previous owner / workshop may not have put all the parts back together in the right order. You'll be surprised how often this happens (I worked in a bike shop a few years ago). Oh yeah - fork springs are tapered so the coils are "tighter" at one end compared to the other. Always have the spring so the "tighter" end is at the fork cap.
All this is quite easy once you get stuck into it - and you'll be satisfied that you did it yourself, you saved yourself money, and you know it's done right.