Need fork seals- any advice?

I tried to slowly (hand) pump my air forks, and noticed that the air leaks back out in about 2 minutes.
So- what type (brand) of fork seals work well on an '82 XJ750 Maxin. I see a few different brands offered on-line.
Also, how difficult is the actual replacement? My Yamaha shop manual has instructions, and they refrence the special tool to seat the seals- is this really needed?
Thanks for your thoughts-
Bill in Loganville

 

Are you sure it's leaking at the seals and not the schrader valve(air valve).
I replaced the valve cores in mine with the short automotive ones they work great. Got them at Advance AutoParts for a couple bucks.
Do your fork seals show signs of leaking? Do they look cracked?
I'd check the valve cores first.
I think snosheriff had the same thing happen to his bike.

 

Definitely check the air valves first. Failing that, the best replacements for these beasts has been the factory seals at twice the price of aftermarket. I've run aftermarket without issue but I have heard from several sources (a few in our numbers) that have had issues and swear by the factory seals. I've compaired the two and the factory appear to be better constructed to my eye. Schrader valve first, fork seals second. They are not that difficult if you happen to have an impact gun. The fork tube bolt on the bottom of the tube can be a real pain if you don't have the toy to hold the keeper inside the tubing. A quick shot with the impact has always made my life a lot easier. Don't forget to put it all back together in the correct sequence or you'll have trouble. I've also heard (again, somewhere on this site) that you can remove the spring, fill the tubes completely with oil, close the tube and force the seal out in that fashion. Sounds plausible but I've never tried it. They did mention it was a bit messy too. Let us know where you end up and we'll chip in to help out. Good luck!

 

ye i have same prob here

oil leaks very badly and wets rotor!!

so do u need a special tool?

if so what for?

and can i do it without it?

thx

 

Ditto on the factory seals. I had already bought the "Leak Proof" seals and after seeing the factory seals bought them. Still have the others sitting on my pc desk.
The special tool is used to hold the top of the damper rod while loosening the bottom allen bolt that holds it in and holds the fork leg to the stanchion tube. All you need is a sparkplug socket and about 3 long extensions. Reverse the sparkplug socket on the extension so that you have the hex sided part going toward the damper rod. Some sparkplug sockets are different so just make sure a 19mm wrench fits the hex sided end. Let a buddy hold it in place while you turn the allen bolt on the bottom end of the fork leg.
I removed the old seals using a slide hammer with a three prong puller. The slide hammer part is over kill but the tool was free to rent from Auto Zone.

 

The spark plug wrench is a great idea Max! I just stacked some 19mm nuts on a 19mm bolt and tightened them all down real good. Then I dropped the bolt head down with all the nuts into the tube and put a deep socket on the nuts with a bunch of extensions. Of course I graduated to an electric impact driver and don't have to do that anymore. I don't suppose there are any Auto Zones in Guatemala are there Secaman? The puller Max suggested is a great idea too. I always used a seal puller and ended up scoring my seal seat with the stupid thing. Arrgh! Hope this helps. Secaman, have you looked at Harbor Freights web site yet? I don't know if they ship to Guatemala but it's worth a shot, they have an electric impact gun for about $40 and a slide hammer set up cheap. Might be an option for you. And DONT ride with contaminated rotors!!!!!!! Get those seals replaced pronto! All the best, Rob.

 

nope we dont have it here

but from what i heard from you

it's a reat (cheap) place!

www.harborfreights.com ?

 

Re: Need fork seals- Update

Yesterday I replaced the Schrader valve in the air nozzle, and I still have the slow air leak, so I guess the seals need replacing. However, after doing some further research and speaking with a local dealer mechanic, it seems as if the air fork on the XJ750 is not too desireable. In fact, one review I read from Cycle World (back in 1982) suggests replacing the stock fork springs with Progreesive Springs, and running without any air pressure. Right now, the forks don't bottom out and I don't see any oil leakage, so I may let things ride. AFAIK, it may already have Progressives in there.
Question for those of you that do run air in these forks- how many pounds do you prefer? How does the air affect the feel of the suspension?
Bill

'82 XJ750 Maxim

 

Well I just started riding mine so I can only tell you from my experience.
I recently built my forks. I put 7lbs. at first and kept getting a jumping or up and down shake. I increased the pressure to 12lbs. and it seems to be better.
But I also have a bad rear shock problem, so I don't know if the rear is affecting this or not. I ordered new shocks this morning.
Progressive springs will be next on my list, I didn't have the funds when I built my forks.

 

One of my seals is moist too. Though, I'm not there yet. I'll keep progressives in mind. A friend had a Yamaha back in the 70's , did a wheelie came down and blew both fork seals. I wonder if this is a weak point of the bike. Achilles seal!

 

It sounds to me like you have an air leak, which would only require replacement of the o-rings that seal the air valve assembly at the top of the tubes. This would not require disassembly of the forks, just remove them from the bike and slide the valve up.

Now, as for the replacements: Don't buy the cheap ones. Chacal has good ones. The cheap ones on ebay are not worth it. Spend the extra few dollars or redo the seals in a couple years when the cheap chinese rubber deteriorates. Unless you just enjoy tearing the front end apart every couple of years.

 

Heres a picture intensive thread I made while rebuilding my XJ750 Seca forks. Yours dont have the antidive so they are MUCH simpler.
http://xjbikes.com/Forums/viewtopic/t=41895.html

Id suggest buying the oil seals, dust seal and oil from Chacal at a minimum. The seal which is visible is actually the dust seal/wiper, the oil seal is hidden underneath. I spent about $400-$500 rebuilding mine, and a lot of the clips or orings can probably be reused in retrospect. Be prepared to replace the upper and lower bushings. A turkey baster is perfect for filling the forks afterwards, Walmart has a 30ml syringe one with ml markings down the side, perfect. Pay extra close attention to the disassembly order. There are washers and seals which must not only be in correct order, they must be facing the correct direction(the wave washers when you pull the bottom bolt and the washers between the dust seal, oil seal and upper bushing. Once you remove the bottom bolt and start slide hammering the upper to get it out of the lower tube, the two thin washers on the oil lock/bypass valve will be loose and can easily be damaged by slamming the upper tube back down into the lower tube.
Take one fork completely apart, once you begin reassembly of it you can dismantle the second one if you forgot the order of assembly.

 

http://www.xjbikes.com/Forums/viewtopic ... rt=30.html

See my thread...I replaced mine last Oct on an 1982 XJ750J Maxim