If it's the twin cylinder model check the starter clutch. If it came apart as some do it can and will lock it up tight.

 

it is the twin cylinder model.
i'll check that out.
thanks

 

Prop the bike leaning to the right at about the same angle as it would be on the kick stand and you'll not lose much oil.

 

both engines i have are out of the bike frames, so i'll just lean them over a bit to work on them. thanks.

any ideas as to the initial knocking i was hearing? it seemed to be in the top end. i've never ripped an engine apart so i don't have many leads yet.

 

kz400.com

This webite shows a guy rebuilding one with good pics. It might help.

 

Without having heard it I really can't even guess.

 

update

here's some more info:

1981 KZ440 LTD - Chain drive, 2 Cyl, ~12,000 miles

the only thing missing (besides the engine now . . .) is part of the air filter + element. i have the air box on it, but it's missing an attachment that houses the actual filter. pretty common to be missing off of these bikes (used) from what i've read.

i started pulling the engine apart today. its looks like its the 1st time its been apart, so if anyone can give advice and/or suggestions if anytime looks funny (since i've never done this before . . .) it would be much appreciated.

here goes:

i have the piston bosses off now. i haven't seen anything blatantly broken yet. there seems to have been some rubbing against the right piston shown in the picture. and the left side seems like its getting more oil than the right (the right side being pretty dry actually). i'm trying to find the source of the original knocking sound i was getting. maybe thats what the "rubbing" marks are from?

 

Looks pretty normal for an engine with a good many miles. Oil on top of the one piston would suggest leaking valve seals. Knocking could have been "detonation". Check the piston wrist pins are in tolerance and the rod bearings. Is that scoring or just the way the light is hitting the cam cradle between bolt holes 6-8?