Shifter won't return

On the KZ750 ('81) when I am riding I can shift up just fine but most of the time when shifting down, I can normally get to 4th or 3rd gear with no problem but when trying to shift lower I can not. The shifter doesn't seem to want to return upward once in the next gear down. It just sits there at the bottom.

Sometimes it will pop up and allow me to shift to the next gear. Seems to be more willing to pop the shifter up if the engine is in the higher RPM's. Once the RPM's go down it doesn't want to pop up at all. Currently I can't even get it in neutral. It's sitting in the garage in 3rd or 4th right now.

The oil level is at the top of the max fill mark. The oil and filter no doubt need to be changed. I picked it up a few months back and have been working on some mechanical stuff such as carbs, electrical (coils, regulator and wiring) and also cosmetics. Now working out the rest of the kinks on the mechanical side.

Any suggestions on the shifter problems?

I am sure that those with more experience than myself will chime in...But on my 650, when last I replaced my clutch cable, I had a hella time with binding shifter after cover installation...(they do make a special pilot tool to keep it centered while tightening cover bolts) fiddled & wiggled it while tightening, took a couple tries...Did you grease the shifter shaft seals? That helped iimmensely in my case.

No I did not and it is horribly dirty (greasy) in there. I will clean out under that cover tomorrow evening and grease the shaft and check the shaft to ensure everything is lining up. Thank you for your suggestion. I think there is a pretty good chance that what you suggest is the issue. The whole cover is only held on by a single bolt at the top. The p/o broke all the other bolts off when he tried to remove the cover. I am planning to Heli-coil them all but haven't done it yet. Looks like I will be working on that tomorrow. I should be able to get to a few without removing the engine.

Thank you again.

No probs! Hope that fixes it! I would defiinitely address the cover bolt situation though! Stand to the left of the bike, watch the cover while you squeeze clutch lever...the whole cover will move outward, as if it's "breathing....probably not good! LOL!

lol, you are exactly right. That is exactly what it does. I had seen that before. Also the last bolt holding it on stripped the treads out of the hole so looks like I am being forced to heli-coil. That's what I am working on right now.

As far as the clutch problems, I cleaned up and it seemed to shift alot easier but still not returning to center. I think the clutch cable may have been too tight thought (assuming that might cause the sympton) as with the cover off I am having to shift gears and the shifter clearly returns to center.

After I heli-coil a couple of these bolts I will tweak the cable some more and take her for a ride. Probably going to be tomorrow before I get a ride in.

Pretty sure those shifter shaft seals are still available, and are pretty cheap...def clean & lube the old ones first...that might do it...I have a chunk of the bottom rear bolt broken off in the block's boss down there...ask me how I know about the "breathing" LOL!

Does the 750 use the "lobster claw" and spring on shift linkage like the 900/1000?
Maybe check the spring.
It will be behind the cover under counter shaft sprocket if it does.