Forks: To rebuild or reseal?

I've got a 650 and drained some old muddy oil out of the forks which are leaking.

My question is can I get away with flushing them with solvent and then ATF and just replacing the seal without taking them apart or is it worth it to do a complete tear down? Please keep in mind I'm on a budget and summer is fleeting! Thanks in advance for the knowledge. Also if there is anyone who has a link to a good fork rebuild tutorial that would be cool.

If you don't have it, then purchase a used Kawasaki shop manual (not Clymer, etc.) from eBay...this will detail the steps need to rebuild your forks. Special tools are required (but it is possible to fabricate some of these). You should disassemble your forks to replace the seals. I'm sure someone will drop in and provide a link if this manual is on-line free somewhere

I just rebuilt my forks Saturday to replace the leaky seals. It's easy as pie. I putzed around and took most of the day to do it, but really it's not a long job. Get your seals, Z1 Enterprises will ship them to you for about $15. Use 15w fork oil, I think ATF is too thin. Buy a seal puller at the auto store



With the bike on center stand, and get something like a jack, jackstand or wood block as a support under the engine. Once you remove the front end the bike will want to fall forward, so support it.

Remove the front wheel and fender. Insert a thin piece of wood between the caliper brake pads and tape it in there to hold it. This keeps the brake in good shape in case the lever gets squeezed. Unbolt the caliper and use something to hold it up out of the way, some string or wire will do.



Before you pull the forks off loosen the handlebars out of the way and remove the top bolt from the forks. The spring will pop up an inch so hang on to the cap, nothing to worry about. Snug up the handlebars again.

Loosen the fork clamp bolts and twist out the forks.
Remove the spring and drain the rest of the oil out.

At this point you need to remove the allen bolt on the bottom of the fork. By far the easiest way is with an impact wrench; get an air, electric, or battery powered one, it won't matter.



If this is not an option then you need to take a broom stick and cut a V wedge in the bottom and jam it in the tube (where the fork spring was) to hold the inner parts while you take a wrench to the bolt.

Once you have the parts out clean them up. I use kerosene.

Remove the clip and flat washer that holds in the seal. Use the seal puller and a piece of hardwood or soft metal as a fulcrum for the puller. Hook the bottom of the seal and pry it out. Try not to damage the aluminum fork.

I use a little grease on the outside of the seal and the fork before gently tapping the seal in with a block of wood and hammer. Make sure it goes in straight. To get the seal all the way down and seated you need something the same diameter as the seal. I have a PVC pipe fitting that's a mm or two smaller OD and I used that. Tap it down and replace the washer and clip on the seal.

Replace the innards in the fork tube and use some liquid gasket on the small washer on that allen bolt. Put some blue loctite, NOT RED LOCTITE, on the bolt threads and use the broomstick to hold the works while you torque the bolt to something like 16-19 ft/lbs. Check the manual for torque settings. Remember to put the drain screw back in the fork bottom.

Get some 15w fork oil and measure out what the book says, my '78 used 190cc. Pour it in, drop in the fork spring, screw down the top bolt and that's about it. Put them back on the bike, follow the manual for torque settings.

When you install the wheel make sure the little arrow on the axle caps face forward, and finger tight the cap bolts. Torque the front bolts to about 15 ft/lbs FIRST. Then torque the rear bolts. You will have a gap at the rear bolts, it is normal.

That's it! Enjoy the ride!

By the way, if you have the time this is a good chance to polish and clean up the lower fork tubes before you put them back together. I stripped mine down with stripper, and then used WD40 and regular sandpaper to clean them up. I used 150g and then 220g with lots of wd40 and got them shiny.




Then I polished them with Mothers Mag polish. Before and after pic, the bottom is shinier than the picture shows.

Doing them is so easy after, go ahead & take 'em apart. There's a learning curve, of course, but after doing one, you'll see what I mean.

To make the job less messy: after draining the old fork oil, I poured in some solvent, reinstalled the fork caps, inverted a few times, removed the caps & dumped out the mess, did a second rinse, then proceeded w the job. I used lacquer thinner - it's what I had handy.

An air impact wrench should make removing the bottom allen bolt easy. You could apply some heat to the allen bolt w a propane torch beforehand.

The manual has service limit info for the springs; it may not matter, but I went ahead & measured mine. They're well within spec, but new springs would probably be a good idea.

Well, I had already disassemled and cleaned them but that allen bolt is driving me crazy. I impacted it and it spins freely, i jammed a pointed dowl into it and it cut into the dowl and was not enough to hold it. I took it to a shop and they said to reload the springs to give it some tension and hit it with the impact but still it spins freely. Please help me out. I'm goin to try torchin them a bit next. Thanks for the replies all. I appreciate it.

www.networksplus.net/n0nb/fork/fork.html

Try to make a holder like this link above, or instead of using a pointed stick, make it a 'V' notch on the end of the stick and jam that on the part.

Thanks duder, you're awsome, that just what I was looking for.

What year 650? Or, do you know what the head of the damper rod looks like (inner cylinder)? Is there a welder handy? If the head is smooth like in the pic below, you may have to fab the tool - the tip of the special tool looks kinda like a pyramid.

I rigged up a long woodworking clamp to jam a rake handle against the head of the damper rod. With some blocking, a pipe wrench & vise grips holding everything in place, I was able to stand on the end of the fork w one foot & stomp on the ratchet handle w the other to spin the allen bolt.

Here's the pic of 70's 650 damper rod:
....

Damnit,that is what it looks like, the bolt can be reached down inside there correct? Or do I have to stop that from spinning, which I've tried may times in vain.

Apply some heat to the allen bolt using a propane torch.

You have to stop the damper rod from spinning.
The special tool is made of metal, so it'll grip better than wood.

The heat may preclude the need for the special tool.
Apply heat, dunk in water. Etc if necessary.