front fork dampering

i have a 78 kz 650 b model and i only have a problem with my front forks whenever i am stoping they seem to be traveling too far and it has scraped my front finder on the header. the suspension is good and firm other wise and just sitting trying to push them down you only get about two and a half inches of travel. thats with me doing it and i weigh 220. they seem solid as in no air pocket give to them but was wondering if they are adjustable some how or if i have other problems?

check the oil and some forks have a air valve too.
not familiar with your bike but mine had loads of travel too.
replace seals filled with oil and they were much better.

ok thanks. i have checked the seals and i dont have any leaks that are coming out of the shocks. they seem to be ok in that retrospect.

Might be a good idea to maybe drain them out and re-fill them with maybe some 15W oil since you're a heavier rider.

When you're stationary and trying to push them down, you're only really fighting the spring as its a viscous damper. When you're braking, as its a dynamic force, damping comes into effect. I'd say either you have some old low weight oil in there or you have a stuck open valve. You should have seen the gunk that came out of my shocks last time I changed the oil. I put new stuff in, rode it for a few days, still squishy, so I drained it again, oil came out pretty black-ish, filled it up again, rode it all fall. Now I'm gonna change it again when I put in my progressive springs in May, hopefully it'll come out a bit cleaner, I dont really want to go in there but it might be a last resort to get them clean.

ok i didn't think about old fluid in there lol so just a staight 15 weight oil should be ok then?

Yeah, I use straight 10W detergent free oil in mine, but you're a bit heavier so 15W I think would be good.

I'm probably going with 15W this summer since my rears are now very stiff, and I'm putting progressive springs in the forks. Gonna be a bit rough, but fun in the twisties.

yeah i know what you mean about the twisties i just went on a ride two days ago to brown count in indiana its around little nashville and there is plenty of those lol i did have that nose dive so i had to take it easy on some of them but other than that it was a wonderfull trip!!!!

When you rebuild your forks, be sure to measure the free spring length - there should be a service limit listed in the factory manual. Others have mentioned that the stock springs aren't the greatest, and they've suggested getting new progressives.

I rebuilt/refurbished the forks on my 81 650 a couple of years ago. Each spring measured >508mm, which is above the service limit of 497mm (your svc limit will be less - most likely). I don't know what their length was when new. After reassembly, the correct amount of the specified 10W fork oil was used, and they're aired up to ~12 psi. I guess the front suspension is fine, but it could be better I suppose. One of these days I'll try a heavier oil or go ahead & splurge for some new modern springs.

USE FORK OIL - NOT MOTOR OIL!!! Every motorcycle shop on the planet sells it. Bel Ray is an outstanding product, but there are others that will also work. Fork oil is meant to be used in hydraulic systems; motor oil is a lubricant intended to reduce friction between metal parts. The two are NOT the same. Just like olive oil isn't the same as cutting oil. You should get a Kawasaki factory service manual for your bike so you can perform all the normal maintenance items. They're always available on eBay. Ed

ok now how do i know when they are full?????

chevyhead wrote:

ok now how do i know when they are full?????

FSM should specify volume when filled "dry" (as after overhaul or complete draining) and maybe also the volume when drained and refilled "wet".

If lucky, the FSM or some other source, may reveal the measurement of fluid level from top of fork tube (with front wheel suspended and spring remaining inside the fork). Makes it easy to check. Once level and volume are known correct to specs, just fashion a "dip-stick' from a wooden dowel or whatever.

Good Luck!

Be carefull when changing the oil in the front forks especially if you have an air valve on the suspension system. If you don't let the pressure out,you will get an unexpected shower when the fork drain screws are removed!!!