engine sticky when hot?

Hi,

I experience something that I don't understand. I'll try to describe it, and if it rings a bell, please tell me your ideas.

So I start the engine, with the electric starter it rotates quickly and starts instantly. When it is warmed up it idles around 1100rpm. Then I pull the clutch, switch to first gear, and it idles at around 1100, and the bike stays put.

Now after some half of an hour later in the traffic jam, I see a different behaviour: the idle speed in neutral is around 900rpm or lower. Many times when I stop at a red light I have to keep the engine running with applying a little throttle, else it would stop. When I switch to gear, it seems that the clutch is sticky, the rpm drops somewhat, and the bike would crawl forward, so at the red light when in the first gear I have to brace my legs against it, and also keep the engine speed with the throttle.
Sometimes I don't give throttle, or something, so the engine stops. I try to start it, and the starter motor turns it slower than normal, and it takes some time for it to start.

I think that this only happens in the traffic jam, and when I can go faster, it is gone.

Of course I would like to see the first behaviour.

So, what do you think, what can cause this? Overheating? Something sticks? Can it be the oil? I have changed it in May, some 500-600 kms ago. But I couldn't change the oil filter in May, so it is possible that there is some old oil in the system (old is 2002 in this case).

Cheers,
Gabor

Your clutch is dragging when the engine warms up. It could be caused by too much free play, the cable, the worm gear, the clutch plates or the oil.

What bike is it? 2002 vintage oil is realy something that needs to be addressed.

gee wrote:

...But I couldn't change the oil filter in May, so it is possible that there is some old oil in the system (old is 2002 in this case)....

Dude. Seriously. Don't sweat the oil, but filters are just not designed to live that long. What if the element is breaking down and circulating through the engine? Don't mean to scare you , just mentioning a possiblity...

Besides what larrycavan mentioned, you might want to check your clutch cable and see if it's fraying and stretching, too. The description reminded me of when my clutch cable broke... slowly ... over about a week plus... while I waited for the new one to arrive.. I *know* I shouldn't have been riding it...

Some more suggestions in addition to the ones above.
Maybe it's time for a good overall tune up. Check timing. Check valve clearances. Synchronise carbs. Check crankcase breather for blockage ....if you have one.

All of the above being out of whack have given me the same symptoms you describe

Your clutch is dragging when the engine warms up. It could be caused by too much free play, the cable, the worm gear, the clutch plates or the oil.

How can I check these?

Too much free play for example? Free play at the clutch lever? It's normal there, 1-2 mm.

I don't know about the others what shall I look for? How do I check the cable, the worm gear or the plates?

What bike is it? 2002 vintage oil is realy something that needs to be addressed.

It's a KZ650, from 1978 I think. I have bought it in 2002, and rode it that year and 2003, then it did not stick. Then I was working in France for 2 years, and the bike just stood in a garage. This year I have changed the oil, cleaned the carbs, changed the battery, and that's it, it's on the road again. I wanted to change the old filter along with the oil, but I couldn't move the screw securing the cover. And I didn't have the time.

Next time when I change the oil (next spring I suppose) I will have the right tools, when I have the time, and will start with the filter.

Or probably I will drain it during the winter, just to be sure.

well to change the oil filter all i needed was a socket wrench and a 17mm socket and it will give some trouble to get out from in the exhaust, but once you feel thescrew is loose from the hole, I think i had to be tough and wriggle it out sideways

Those symptoms all point to overheat.

KawasakiJockey wrote:

Those symptoms all point to overheat.

thats what i was thinkin too

install an oil cooler as a fix??