Clutch slipping; wrong oil?

KZ650 B3

I've been trying to get the bike running right since I bought it in July. Finally have it sorted out, and am doing my first real riding on it.

I got on it last night. Under full throttle, the clutch slips pretty bad when I shift into second. Under normal driving, it's not a problem.

I'm wondering if the oil I'm using has anything to do with it. It's Castrol High Mileage 10w 30.

It's probably the clutch itself slipping (worn plates); the oils that cause clutch slippage are straight-synthetics and it's more normally associated with newer/extreme high-rpm motors...as I don't know anyone who has an air-cooled motor who runs straight synthetic.
I run Castrol in all my air-cooled bikes and have never had oil-related problems.
-KR

I am thinking the seal conditioners to help reduce leakage in that specific type of oil might cause a problem.
Although I have never used that brand.

Have you gone through the clutch adjustment?

I've learned recently to check not only the cable, but the pushrod as well (adjustable via the side cover). Seems to me that if it were a little tight, it would cause slippage.

Could be the adjustment, not just the oil.

Actually all the pushrod adjustment does is basically the same thing as setting the free play on the cable does. If you have ample free play in the lever, both the cable and the pushrod are set up good enough for normal clutch operation so if it slips you need plates replaced. The pushrod adjustment behind the cover is slightly more than the cable adjustment as it determines the angle of the clutch release mech arm so the cable can get the most efficient pull of the clutch. You can tell easily if the pushrod needs adjusting by simply looking at the 2 screws that hold the cover on. Are they all chewed up/stripped/beat up in any fashion? Yes= someone has fooled with the adjustment and it's all goofed up. Are the screws original untampered with? Yes= set up at the factory and no need to ever fool with for the entire life of the engine.

When mine started slipping at about 40k miles, I figured it was worn so I ordered a new spring and plate set. It turns out it was just weak springs. The plates had hardly any wear.

The motor oil to avoid is the stuff that says "energy conserving blend" or something like that because it has additives that get into the friction plates and make them slip. Most oils don't have it, I think Mobil-1 does and maybe Pennzoil (check the labels). I don't think any Castrol has anything bad in it, I used castrol many times in my bike.

Bad Kaw wrote:

as I don't know anyone who has an air-cooled motor who runs straight synthetic.

I thought everybody had switched to syn by now, I have been running it in my KZ-750 for many years. It actually stands up better to the high temps and shearing associated with bike engines.

I also used castrol regular for a lot of years before syn became available. It's good oil, I think the new syns are better, but castrol is probably the best of the conventional oils.

I remember that the other Kawasaki forum has extensive material on the question of dino oil versus syn oil and somebody there actually runs oil and has it analyzed to see the chemical properties after running it. The question keeps getting kicked around.

Here's a long thread on oil with a lot of very good information:

www.kawasakimotorcycle.org/forum/kawasak...l-vs-automotive.html

I been using the Mobile-1 fully synthetic motorcycle oil and found that the bike seems to run smoother. I've had no clutch (or any other) problems. It's not cheap, but I'm sold on it. Here's the info:

Synthetic Motorcycle Oil

Have you taken the clutch plates out and cleaned them? If not, try that. Take all the plates out, wipe them off and lightly sand them with emery cloth. It makes a huge difference if this is the problem. Do both the friction and metal plates. I sand til I see the friction plates have a dull look to them and the steel plates have light sanding scratches in them. It doesn't take much. You will when you have sanded enough. All you are doing is taking any glazing off the plates so they can grab each other. I have heard some guys say that some of the synthetic oils can be too slippery and can cause clutch slippage but it seems to be hit and miss on it though. Some have problems and some don't. Why? Not a clue. I personally use Castrol regular motor oil without a problem. You shouldn't need anything more than stock springs unless you have increased HP a lot. They could be weak but I would guess it's something else unless your mileage is way up there like bountyhunters.

Hey BadKaw,

You said "I don't know anyone who has an air-cooled motor who runs straight synthetic."

Sorry Guy! Ive been running straight AMS oil in more bikes that I can count and NEVER had a leak or a slipping clutch.

Did I forget to add that my KZ900, which I've owned since new, has never seen anything but AMS oil since about 5K miles and it's doing fine.

Let's look somewhere else for this guy's problem.

KZCSI

I also have been using Mobil 1 (full syn) for many years in my Z1R, drag racing, road racing, cruising, and highway hauling, narry a slip or any oil related problems.