KZ650 vs KZ750 clutch

I agree with Irish Yobba; just because an oil is not tested for MA that doesn't mean it's bad for bikes. I've used various types of diesel oil over the years and all have been fine.

BTW, Rotella is MA certified. The only diesel oil that is to my knowledge.

Irish Yobbo wrote: ............. there are plenty of oils that are not JASO-MA but will work just fine. Just because an oil has not been tested for compliance doesn't mean it won't work. There are many people who swear by Shell Rotella in motorcycles, and that's a heavy duty diesel oil.I've never tried it personally, it's not JASO-MA, but it is very well tested.............

Shell Rotella actually IS JASO-MA certified, and that certification in printed on the label. I've been using it for several years in my KZ650. Ed

Nessism wrote: BTW, Rotella is MA certified. The only diesel oil that is to my knowledge.

650ed wrote: Shell Rotella actually IS JASO-MA certified, and that certification in printed on the label. I've been using it for several years in my KZ650. Ed

Well TIL. Perhaps I'm just showing my age - I can find some forum posts from 11 years ago when they were talking about how they had just added the rating.

For the record I've never used the stuff, it doesn't seem common in Australia. But it comes highly recommended on just about every motorcycle forum. For the record I use Penrite HPR Gas10 in my motorbikes, it's always worked well for me.

Nessism wrote: Have you adjusted the clutch per the factory manual specs? I'd do that and lube the clutch cable before looking at changing parts.

Oils get way too much blame when clutches start slipping. Most of the time when parts need replacing it's just the springs anyway.

BTW, what kind of oil did you use? A motorcycle oil that damages clutch plates would be extremely unusual. Only oils with friction modifiers do that.

It is Castrol 20w50 4t motorcycle oil. Now I just looked for it to send you a picture and the one I found did mention JASO-MA compliance - so that just points more sharply at friction plates or springs as you say.
I have made the factory adjustment of the clutch, but I have not lubricated the cable - I will try that as well and see if it totally disengages properly each time. Thanks a lot for the tips!

q-base wrote: It is Castrol 20w50 4t motorcycle oil.

Having a 20W oil might be a little thick when cold, and that could also cause issues with a slipping clutch. It shouldn't cause the clutch to slip on its own, but combined with some age and wear a 20W oil might put it over the edge. Best to stick with a 10W if you can.

But yes, the first thing to do is go through all the adjustments - lube the cable, set the push-rod adjustment screw to the correct level, and make sure the push-rod lever itself is clean and lubed (if it's corroded or just dry it can catch and not return completely). Once that's all done, the next step is to try changing the oil, and if that's still no good, it's time to look at the plates and springs.

Irish Yobbo wrote:

q-base wrote: It is Castrol 20w50 4t motorcycle oil.

Having a 20W oil might be a little thick when cold, and that could also cause issues with a slipping clutch. It shouldn't cause the clutch to slip on its own, but combined with some age and wear a 20W oil might put it over the edge. Best to stick with a 10W if you can.

But yes, the first thing to do is go through all the adjustments - lube the cable, set the push-rod adjustment screw to the correct level, and make sure the push-rod lever itself is clean and lubed (if it's corroded or just dry it can catch and not return completely). Once that's all done, the next step is to try changing the oil, and if that's still no good, it's time to look at the plates and springs.

Yes I also plan to go with 10w after I change the plates and springs. I will give it a last shot with the cable, but I would be surprised if that changes anything.

20W-50 oil won't cause the clutch to slip. I'd change the clutch springs first and the friction plates if that's not enough. Grease the cover gasket so it won't stick just in case.

Shell Rotella t4 is definitely JASO-MA approved. Use it