Strange transmission issue

though I am NOT new at all to bike, I'm new to this problem ( which some of you guys will probably slap me for even asking....But here is my problem... When I roll on my throttle, all is good in the world, My KZ 750 would pull hell outta the ground ( if the devil would hold the chain) but when I hammer it sometimes, it's like the clutch loses grip and just free spins till I back off a little and give it time to grab....My bike is an '81, and only has 10K miles but I know that means little, what could it be? it happens in multiple gears and I just don;'t have enugh mechanical knowledge to know what this problem is....HELP ME!!!!!

Wrong kind of oil?

I'm using penzoil 10W40 like the cap and manual says...or is there something I am missing ( like the manual that I think my wife threw away....)

Your clutch is slipping. You should adjust it PROPERLY using the instructions in the Kawasaki Service Manual. Also, as elfmagic17 says, you may be using the wrong motor oil. Your oil should be designated JASO-MA on the container; otherwise it can lead to the clutch slipping as you describe - oil formulas have changed over the years and most car oils now contain friction modifiers that will damage wet clutches. If you adjust it correctly and it still slips you may get away with removing the clutch plates, cleaning them, and re-installing them. Don't even start that job without the manual. Ed

Thanks Ed, I will Definately look into it!!

An expanded explanation of engine oils:

JASO OIL SPECS:
Find an oil that shows the JASO-MA rating on the bottle; there are plenty of them available both dino and synthetic.

The ingredients in oils have changed over the years. For example, today's Castrol GTX oil (and pretty much all other AUTOMOBILE oil) is not the same as it was in the 1980's. Back then it worked great in KZ bikes. But, things have changed. Early AUTOMOBILE oils contained zinc phosphorus compounds (ZDDP) to protect engines from metal to metal contact. This was good for engines, but it was found to be destructive to catalytic converters. Consequently, in AUTOMOBILE oils ZDDP was virtually eliminated and replaced with different chemistry generically referred to as "Friction Modifiers."

These work fine and offer good protection for normal AUTOMOBILE engines. However, today's AUTOMOBILE oil "Friction Modifiers" are destructive to wet clutches. KZ bikes (and many other brands) have wet clutches. As a result of these oil chemistry changes a distinction needed to be made between those oils which are suitable for wet clutches and those which are not.

That distinction was documented by the Japanese Engine Oil Standards Implementation Panel (JASO). JASO developed a number of different oil specifications for different applications. The specifications that apply to 4 stroke motorcycles fall under the "4T Specifications." Within the 4T specifications the JASO MA class oils are specifically formulated for 4 stroke motorcycles with wet clutches.

Using oils that are not designated as meeting the JASO-MA standard may be destructive to KZ clutches. Here's a link that may be helpful:

JASO Oil Specifications - oilspecifications.org

Ok, so say I change my oil tomorrow....what oil SHOULD I use?

Shell Rotella 10w30 should work for you,10w40 if you live in a hot climate.

I'm In hot/Humid GA, so I tend to stick with 10w40....I will give the rotella a go.

Clutch push rod adjustment -- Need and Purpose
[This is a 1 minute job from start to finish, maybe 2 minutes the first time.]

The FSM covering Z1 and KZ900 includes a periodic maintenance chart requiring clutch push rod adjustment at 2000 mile (3000 km) intervals and explains the need therefor in separate text, which explanation is quoted verbatim as follows:

Besides cable stretch, clutch plate wear also causes the clutch to go out of adjustment, with a decrease in push rod play. Due to this wear, the push rod gradually moves closer to the clutch release lever (at the lower end of the clutch cable) until it touches the adjusting screw. When the rod is touching the screw and therefore has no play, the clutch will not engage fully and clutch slippage will occur. Note that the clutch push rod does not necessarily have play just because the clutch hand lever has play, and so hand lever play alone cannot be used to determine whether or not the clutch requires adjustment.


The FSM covering '77-'79 KZ1000's includes a periodic maintenance chart requiring clutch adjustment at 5000 km intervals, and explains the need therefor in slightly different language, which explanation is quoted verbatim as follows:

Clutch plate wear also causes the clutch to go out of adjustment. This wear causes the play between the push rod and the adjusting screw to gradually diminish until the push rod touches the adjusting screw. When this play is lost, the clutch will not engage fully, causing the clutch to slip.
NOTE: Even though the proper amount of play exists at the clutch lever, clutch lever play alone cannot be used to determine whether or not the clutch requires adjustment.

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end of excerpt

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Good Fortune!

If your bike is 4 cylinder you can download a manual here
mbsween.bike-night.com/kz750l3/index.html
Courtesy of mbsween a member here. Clutch adjustment is easy, just follow the procedure. Also make sure the cable is not snagged up somewhere. I had my exhaust off recently and managed to snag the mid cable adjuster between the frame and the header when I reassembled which did some weird things.

did you recently change your oil ?
possible incorrect clutch adjustment at the cable and/or on the engine or weak clutch springs ...... :dry: