1978 kz750 engine noise

first off new to forum so hello but i have been searching the forums for a while trying to find answer to my question ok my kz750 has a rattle like a chain slap at a sertain rpm goes away at higher rpm and lower and only seems to do it 4th or 5th gear also feels like the drive sprockets and chain is grinding then it happens like its slipping chain is adjusted just right i have checked the valves, timimg,carbs have been rebuilt and jetted for uni pod filters i completely removed the starter clutch and chain cause i thought that might have been the problum good thing i did one bolt was sheared off and they all where loose but this did not fix the problum the timing chain guides look good just woundering if anyone has a clue before i pull the right side cover on the primary side and the oil pan also the bike only has 14,000 orginal miles and shifts good through the gears and runs like a dream other that that noise hope its not the tranny

welcome to the forum.

There are only three chains inside the engine that I know of: the camshaft drive chain, the primary drive chain, and the balancer chain. If you hear a chain inside the engine, it's got to be one of those.

I think my primary chain makes a loud clack every now and then when the engine is idling, but the engine has 75k miles on it. I never hear the other two.

The only thing I can think of is maybe your cam chain tensioner is funky?

The other thing is it may just be your external drive chain and/or sprocket. At least those are easy to change and relatively cheap. If your bike has 14k miles on the original chain, it's time to chuck it.

Chuck the chain, Keep the bike.:dry: