squishy forks

took the forks off my 78 650b today and took them apart.cleaned al the parts. installed new seals and put them back together with 190cc or 10w fork oil. they are stll just as squishy, only they dont leak oil now. ay ideas what could be wrong? is m chiltons book correct with the fork oil volume? any ideas at all? thanks guys

By squishy if you mean easy to compress then the springs would be what I'd be checking. Did you check the length of the springs or the sag of the fork after reinstalling them?
If by squishy you mean no dampening then hopefully you put that end of it back together correctly, if so then you can try a heavier weight oil to see if that helps.



The tapered piston at the bottom of the dampening rod must be oriented as shown with the taper up.

Easy fix:
Step 1. Give the Chilton manual to your dog as a chew toy and get a Kawasaki Service Manual.
Step 2. Drain all the 10w oil out of your forks; this is NOT what is called for.
Step 3. Buy some 15w Bel Ray fork oil.
Step 4. With the front wheel raised off the ground (put a bottle jack under engine with bike on center stand) add the 15w fork oil until the oil level is 385mm (15 1/8”) from the top of the inner tube. You can measure this by inserting a thin wooden dowel marked with the measurement.
Step 5. Ride the bike for a couple days then check and if necessary adjust the oil level.

it is squishy as in easy to compress. I did not measure the springs when they were out. do u really think 15w opposed to 10w will make that much difference? if it is the springs is it possible to get new ones? i noticed that just the weight of the bike sitting there ompresses the bike an inch o two...... ideas?

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Two cheap things that you could do. Make a spacer for going between the cap and spring, like maybe 1-1.5", or/ also drill and tap the caps for an air fitting. A bit more preload on the spring, maybe also a few pounds of air, and the 15w oil. Should be a pretty cheap set up, as while the new springs would be great, they are probably about $100 w/shipping.

The weight of oil affects how the suspension reacts to bumps. It will be particularly noticeable on sharp, rapid bumps. The difference between 10 and 15 weight is noticeable, but not dramatic, particularly if everything else is in good shape.

The amount of sag you have seems like a lot; it should be closer to 25 - 30mm. New springs will make a world of difference in how the bike handles and rides. Progressive probably makes the most popular replacement springs, but you might check with Sonic and Racetech as well.

here is some related info

www.onthethrottle.com/howto/setting-sag-...suspension-business/

I just rebuilt the forks on my 1980 650 LTD over the weekend and replaced the springs with new ones from Progressive. I found them through Dennis Kirk here in MN for about $75 and free shipping. If you go this route take note that the Progressive kit specifies that a spacer is not required for KZ650's, but after installing them and calling their tech line, I confirmed that I did need to cut spacers out of PVC to get their suggested pre-load.

650ed wrote: Easy fix:
Step 1. Give the Chilton manual to your dog as a chew toy and get a Kawasaki Service Manual.

Now that's what I call a first step! :lol:

I do feel sorry for the poor dog though as I doubt it will even digest properly! :silly:

Ok, to be fair some of the info is fine in those manuals it is just not one that I would recommend without first having the FSM and using the Cylmer/Chilton as a second reference possibly for the diagrams or photos more than the instructions/specs.

martin_csr wrote: You can get some Progressive springs. I've seen fork springs at Z1Enterprises.com but can't seem to locate them.
If you get new springs, it might be a good idea to upgrade the rear shock absorbers as well. Otherwise, you may end up with a firm front end & a mushy rear.

I rebuilt the forks on my 81 650 & used the specified 10W fork oil. The springs were well within the service limit. I'll use 15W next time, but the bike probably needs a suspension upgrade.

I read this and thought - I just checked the genuine Kawasaki KZ650 manual this morning and verified that it specified 15W fork oil before posting my answer in this thread, so why would Martin say "specified 10W fork oil?" Was he using a Clymer or Haynes manual? Then I though - just for once, before I shoot my big mouth off disputing someone's information let me do a bit more research. Here's what I found. The Kawasaki KZ650 manuals are all over the place regarding the fork oil weight. In them I found multiple places where SAE 10W; SAE 10W20; and SAE 15W were specified. So Martin's assertion of "specified" is also true. Personally, I've always used 15W Bel Ray fork oil and have been very please with the results. Ed

so it sounds to me like some spacers are in order. im not gonna be to thrilled if i order new springs and i end up still needing to make spacers. u say to use PVC....as in PVC pipe....this will hold up to the pressure and abuse without cracking & chiping?? it sounds like i need some 15w oil as well...is 20w overkill/too much? the rear suspension is new and quite a bit stiffer so im excited to finally sort the front end out.