Kawasaki Motorcycle Forums banner
1 - 19 of 19 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
Hello,
Replacing the fork oil and I don't know how to remove the top of the fork to pour in the fork oil. Old oil is drained and drain plugs are screwed back in. Front wheel is suspended.
I've included a picture. I'm reading manuals and seeing "
43343
remove top plug." However, there isn't a step by step procedure.
Thank you for your time.
 

·
Registered
Joined
·
273 Posts
It should unscrew using the hex around the valve to turn it.

If you don’t fancy doing that though, you could remove the valve inner and inject the correct amount of oil through the valve, using a syringe and tube.
 

·
Super Moderator
Joined
·
2,312 Posts
You could certainly try to add oil through the hole once the air valve is removed. But if that is too slow or does not work, then you should remove the fork cap. It is held in place by a circlip and is under spring pressure so be careful. First, bleed off any air pressure. Then remove the top pinch bolt and push down on the cap so it relieves pressure from the circlip and then pry out the circlip. The spring pressure should then push the cap out of the fork tube.
 

·
Registered
Joined
·
4,608 Posts
I would remove the fork caps & completely disassemble the forks to give them a good cleaning. There's a good chance they're overdue for service & the old fork oil is probably going to be nasty. Be sure to relieve the air pressure beforehand. After dumping the old oil (and before disassembly) I poured in some solvent, inverted a few times, dumped that, then proceeded with the job. It's a messy job even after rinsing, but worse without using the solvent rinse.
 

·
Super Moderator
Joined
·
2,312 Posts
It is a lot more work, but I agree with Martin.

A bike this old should have the forks flushed and cleaned. While you are in there, pop in some new fork seals and measure the overall spring length to see if they are still within spec. It might be time for some nice new progressive rate springs.
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #6 ·
Thank you for the input.
I will dive into the suggestions and peruse the Recommended Reading.
I contacted wemoto and they returned my inquiry, stating they sell fork seals.
Lastly, am I simply looking in the wrong places or does information for the 1981 Kawa gpz550 D1 seem very difficult to find?
(Shop manuals, parts, how to info.)
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #7 ·
Ive put a sprocket on the hex nut and it turns, but that's all it does. Just spins.
There's no weight on the front wheel. I've pushed down while turning...
Do I need to loosen the top of the triple tree where it attaches to the top of the forks?
Apologies for what seems to be something I'm obviously missing.
 

·
Super Moderator
Joined
·
2,312 Posts
I think you meant socket and not sprocket LOL. You probably need a deep socket. I am guessing your shallow socket cannot engage the hex because of the air valve hitting the ratchet. Select a 6 point deep socket of the exact correct size.

Slip it on making sure it covers the nut entirely and then rotate it with your fingers forwards and backwards. There should be almost zero play between the socket and the nut. The nut looks a little banged up so you may actually have to remove some burrs before the socket will fit.
 

·
Registered
Joined
·
4,608 Posts
Is the fork cap spinning along with the air valve assy? Already stated above, but you have to remove the circlips to remove fork caps (listed as Fork Spring Seats in the diagrams).

Here's the fork diagram from Partzilla for the 1981 KZ550-D1 (USA):

ps: not sure what brand those Wemoto fork seals are, but I would try to get OEM or K&L. I use K&L made in Japan.
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #11 ·
The entire issue came from the wheel not being completely suspended. Once that was fixed, I could push down on the cap, remove the clip and wallah, the cap popped right off.
I really appreciate you all taking the time to help me.
And I will take your advice on the seals.
 

·
Registered
Joined
·
4,608 Posts
A disclaimer: I've never had a problem with any K&L parts (fork seals, brake caliper rebuild kit & piston, etc), but others will say get only OEM if possible.

Bushings. If the motorcycle has a lot of miles, the bushings may be worn. I don't know anything about replacing those or what to look for. not sure if the manual would say anything about them.
 

·
Super Moderator
Joined
·
2,312 Posts
My manual only says to check for wear on the guide bushings but it does not give any way to measure for wear. I would suggest to assemble without oil seals and then test for play by attempting to wiggle the tube from side to side. But then it is up to you to decide what is acceptable play. Since the oil seal will have to accommodate any side to side play, I would measure it there, and if more than .005" or so I would be looking into new guide bushings. But that is just my guess.
 

·
Registered
Joined
·
10 Posts
I've done a LOT of forks on this vintage bike as part of my business and even way before that for myself. You need to jack up the bike front end, yank the front fender, front wheel and have the forks only attached to the steering tree. To test for guide or slide bushing wear, simply grab the bottom of each fork and try to feel for movement of the fork lowers (the larger aluminum part) in relationship to the top clamped into the bike. You feel for it only. If there's no play, or very little play, the bushings are ok. Check both sides. I've seen one side only being bad and causing a misalignment on that one side causing binding.
You really need to then remove the forks from the bike and at least, pump out the old oil with the top cap and spring/spacers (if any) removed, then upside-down in a pan, pump it out with the fork itself in compression and extension. Then, refill and pump them out again and again until clean. This is if you're not tearing them down. However, I've NEVER just done that, all my fork jobs the forks come apart, everything is cleaned with brake clean and microfiber towels then reassembled with new seals and bushings if required.
You will also likely need a special tool to hold the inner piston while unscrewing the M8 Allen cap bolt on the bottom of the fork leg itself. There's a copper seal washer, replace that. Use Loctite on the bolt and torque to spec, it's very important.

Forks of this vintage are extremely easy, once you do one, every other regardless of brand are a snap. The only significant variable is the special tool needed to hold any fork innards to get them apart, I end up just making one using an appropriate (or approximated) sized bolt and welding to a junk 3/8 drive socket, then a long extension and it's done. Cheers.
 

·
Super Moderator
Joined
·
2,312 Posts
That sounds like a good method. As a retired machinist with dial indicators on hand, I like to put a number on it.

Here is how I disassembled the forks on my 1984 ZN1100. The first picture is the 12 point internal hex of the piston rod.
The 2nd photo shows the long extension needed to hold the male hex socket.

43383

43384
 

·
Registered
Joined
·
29 Posts
Is the fork cap spinning along with the air valve assy? Already stated above, but you have to remove the circlips to remove fork caps (listed as Fork Spring Seats in the diagrams).

Here's the fork diagram from Partzilla for the 1981 KZ550-D1 (USA):

ps: not sure what brand those Wemoto fork seals are, but I would try to get OEM or K&L. I use K&L made in Japan.
Listen to Martin, he is correct. Remove the circlip.
 

·
Super Moderator
Joined
·
2,312 Posts
Listen to Martin, he is correct. Remove the circlip.
Thanks for jumping in Kawasaki Nut, but perhaps you should read the entire thread more carefully before jumping in.

If you did, you would have seen that the owner solved the problem in post #11 not only by following Martin's and my advice to remove the circlip, but he also realized he had to take all weight off the front wheel first.
 

·
Super Moderator
Joined
·
2,312 Posts
Hey no worries at all. We all read too fast sometimes and miss stuff. Been there. Done that.
 
1 - 19 of 19 Posts
Top