TOPIC:

I have a mid-1980s KZ1000P. It does this weird thing, where I'm out on the highway, I start shifting up through the gears, and-- say, for example, I'm in third of fourth gear-- I hit the throttle. The bike accelerates normally, but then it hits this weird spot where it seems like the engine suddenly revs up, the bike doesn't seem to gain any acceleration relative to how hard the engine starts working, and then it seems to rev normally and takes off.

At first I was thinking that maybe the clutch is slipping, but I don't have any shifting issues (no weirdness with the clutch grabbing as I shift). Then it occurred to me that maybe this is some weird ignition advance issue, as this always seems to happen around the same RPM band as I'm up-shifting or getting on the throttle.

Does it seem to anyone out there that this might be caused by a sticking ignition advance unit? 

I'm used to older KZ's that have points and advancers, so I'm not sure yet if this bike even has an ignition advance unit under the cover with the pulse generators-- but it does seem like some kind of weird ignition curve issue.

What do you all think?

It´s the slipping clutch and not the ignition that causes this wierd effect. So higher the driven gear so more torque the clutch has to hold by clutch spring pressure. First to know is your clutch accutator adjusted to spec, if not do it first. A wrong adjusted clutch accutator can cause this effect because of no play and pre-pressure to the clutch push rod. This can cause a "no full surface binding" between the friction and steel plates.

Thanks very much. I'll check out that adjustment tomorrow. If the adjustment doesn't do it, would that likely mean the plates are worn out?

A non JASO MA  spec 4 stroke engine oil can cause a slipping clutch. Don´t use automotive oils, they contain anti friction additives and are used in dry clutch engines.

www.oilspecifications.org/articles/JASO_MA_JASO_MB.php
 

Very interesting-- thanks. I've always just used standard 10-40 (non-synthetic) in my bikes. What do you use?

I use Shell Rotella T4 15W40.  It has the correct JASO certification.   

Your clutch friction plates may be worn, but first you should check your clutch lever to make sure it disengages well before it's fully released.  Sounds to me like it only partially releases.  This is often caused by someone setting the clutch release too close to the end of the lever travel.

Cheap stuff--kawasaki motorcycle oil 20w-50 non-synthetic.


JASO  www.jalos.or.jp/onfile/jaso_e-2.htm

The list from JASO
www.jalos.or.jp/onfile/pdf/4T_EV_LIST.pdf


 

Thanks. I adjusted the clutch actuator, the cable and the lever. I did have the engagement set a way out on the lever, so you may well be right. I've just ridden it up and down my driveway and it does feel better. I'll take it out on the highway tomorrow and report back. Hopefully, I'll have results that will be useful to people checking the forum with similar issues in the future.

Thank you for the oil recommendations as well. Will check them out.

I finally got a chance to check this out and figure out the issue. The issue I was experiencing was due to improperly adjusted clutch actuator and cable. I went through the adjustments, from the actuator to the lever, and it resolved the issue. The clutch as a little pre-loaded.

So, if anybody else ever runs into this issue, maybe this experience will be useful.

Good to hear that you could solve your clutch problem, thanks for the feedback.