'80 KZ1000B4 fork oil

I have some new seals I need to install in my forks so, I thought I'd pull them apart and check them over and clean.

The manual calls for 180-188cc of SAE 10W20 oil. Are they talking motor oil or does fork oil come in multi-viscosity? In the past I've only used single weight oils in forks.

Any recommendations for a good oil to handle my 220lb's and heavy front brake usage?

Sonny

Does your bike have an air valve in one of the fork legs? if so do not forget to bleed this off before doing any maintenance.

My understanding of the oil required is that it is made just for fork applications as the engine oil may not go through the oil control orfices as well as a thin oil will.

As for a good oil choice ask at the bike shops or try the internet for oils.

MFolks wrote:

My understanding of the oil required is that it is made just for fork applications as the engine oil may not go through the oil control orfices as well as a thin oil will.

As for a good oil choice ask at the bike shops or try the internet for oils.

That was my understanding also but, the manual didn't make it clear and, when they recommend multi-viscosity, I just don't ever remember seeing that in fork oil.

As for what oil to use, I was hoping someone on here might have first hand experience as to what weight worked best for my weight and riding style. Otherwise, I'll experiment.

Sonny

sbulla wrote:

I have some new seals I need to install in my forks so, I thought I'd pull them apart and check them over and clean. The manual calls for 180-188cc of SAE 10W20 oil. Are they talking motor oil or does fork oil come in multi-viscosity? In the past I've only used single weight oils in forks. Any recommendations for a good oil to handle my 220lb's and heavy front brake usage?
Sonny

For comparison, FSM for 1977,1978, and 1979 KZ1000 specifies common motor oil SAE 10W for 1977 and 1978, and SAE 10W20 for 1979.

Most bike shops carry various brands of fork oil specifically blended (touted?) for forks. Bel-Ray comes to mind. Many owners use motor oil, others prefer using ATF, and some use fork oil.

Thinking the important thing is to not allow the existing oil to becomed rancid or depleted.

Am guessing the 10W20 would be just fine for 220 lbs and heavy front brake usage, but perhaps not any lesser viscosity. Would use whatever results in performance most preferred, from a softer cushier bump-absorbing "touring" ride to a stiffer more controlled ride usually preferred for higher performance cornering, etc.

On a side note, watch for any front end "wallowing" which might be more prevalent with the lighter weight fork oils, especially during long fast sweepers (and even more-so with a passenger or heavily loaded bike.)

Good Luck!

Patton wrote:

n a side note, watch for any front end "wallowing" which might be more prevalent with the lighter weight fork oils, especially during long fast sweepers (and even more-so with a passenger or heavily loaded bike.)

Good Luck!

I'm getting a bunch of that wallowing you mentioned right now! I think I'm low on fluid as the seals are leaking and the forks are greasy.

Since I just purchased this bike and don't know the maintenance history, I'm going to tear 'em apart and clean them up pronto! I found almost a full quart of Bel-Ray 15w back on the shelf that I used on my other bike (KLR650) so, I think I'll give it a try. It works good on it. Finding 10w20 might prove to be difficult as I usually only see 10w30 or higher in the auto parts stores.

Thanks for the reply,
Sonny

went through this on my 83 750 ltd. Whatever you do DONT use 10 weight .Too light. I ended up using BelRay 20 weight fork oil. Made a hell of a difference.

30w synthetic motor oil works good in the heavier bikes;)