Which fork oil do you prefer?

Hi all,

I finally found a set of original Z1000J forks.

I'll be using the original springs in it. I'll be changing seals and steering bearings. Which fork oil would you recommend? 10W or 15W?

Thanks.

I've been using Bel-Ray 15w fork oil in my 1977 KZ650 forks since my bike was new, and I've never had a fork seal leak in 60k miles. I weighed 165 lbs. in 1977 and 200 lbs. now, and even with a passenger on board the forks perform very well. One nice thing about Bel-Ray is if you find you need to adjust the weight of the fork oil different weights of their product can be mixed with no problems. Also, they make it in 7 different weights ranging from 2.5w - 30w (see link below). I replace the fork oil about every 2 years. Ed

www.belray.com/bel-ray-high-performance-fork-oil

The '79 Z1000 manual says 10W. Not sure about the J bikes though.

Nessism wrote: The '79 Z1000 manual says 10W. Not sure about the J bikes though.

Looks like the "J" calls for 10W20. I see that on page 1-22 in the link below. Ed

www.kzrider.com/modules/ServiceManuals/K...Service%20Manual.pdf

There is a KZ1000/1100 pdf available that has the info for the KZ1000-J1/J2/J3. It has the various specs for the forks.
The fork oil table says to use SAE 10W20. There's also a fork free spring length table.

10W20 = 10W fork oil

The W indicates Winter, which references the viscosity at cold temperature. Fork oil doesn't get overly hot so testing viscosity at high temp isn't typically done, thus the reason fork oil is sold in W grades.

Ok thanks. I'm always tempted to put some heavier oil in older bikes..

Just got my seals and bearings in the post today so I'll be changing them tomorrow.

The KZ1100 has the air-ride suspension, which I eliminated for Progressive fork springs...an incredible improvement in my estimation.
Been using Golden Spectro 15W fork oil. Should the weight choice be different with such a suspension upgrade?

Tell us how it goes with the seals. Lately seals have not been good at all.
Iv tried All Balls to original and both look the same and leak the same.

By Nessism: 10W20 = 10W fork oil The W indicates Winter, which references the viscosity at cold temperature. Fork oil doesn't get overly hot so testing viscosity at high temp isn't typically done, thus the reason fork oil is sold in W grades.

Thanks. it seems odd to me that Kawasaki would specify a multi-weight fork oil. I'm assuming they mean fork oil & not motor oil. I have no idea how much the forks heat up or at what temp 10W20 would act as a 20W. I would probably go with 15W fork oil.

I bought some 10w in the end.

I haven't used allballs yet. I use pyramid fork seals. I've used that brand several times already and never had a leak. Only once after a year but that was due to the condition of the fork.. I installed them again today, without any problems.

But I'm having problems removing the steering head lower cup since I don't have a driver. Tried ticking it out to no avail. It wouldn't move at all. And I'm out of grinding discs for my dremel so it will have to wait till monday.