intermittent lower end knock

i got my bike all together enginewise the other day and started it up. started first kick,and purred like a kitten. sounds wonderful. but after running it for about 30 or so seconds i noticed every few seconds at about 1000 rpm it would make a slight lower end knock. the problem doesnt increase with engine speed though. anyone have any ideas? my thoughts were a) not enough oil pressure, b) backfiring or detonating (since i havent rejetted it for the intake or exhaust) or c) cold engine. not too sure as i havent dealt with a vast amount of kz's

synch your carbs

so you think its just hickuping, as i call it? how do you sync mechanical slides, i have only done it on CV's and cable connected carbs

There should be screws on top to adjust the slides up and down. you will figure it out pritty quick when u take the caps off. Dif carbs use dif meathods.Hope this helps.
I'm sure there will be details in your manual.

i know the screws your talking about. but i thought taking the caps off while the engine is running would alter the vacuum pressure. i guess then again it wouldnt matter that much if all the caps are off. ill do that then.

how many miles has the clutch done?? might also be loose dampersprings in your clutch basket...

im assuming its stock, so about 27k

Capn, light noises from lower end are common at low rpm, usually as M alludes (clutch basket), quick checks, If noise goes away by picking up idle to 1100-1200 rpm, or by slipping into 1st gear and applying light load, be at ease. I've been searching for sewing machine quiet/smooth for years and it's elluded me so far.G

A sad/funny tale for you. My '74 Z1A had a similiar "knock" at idle. The sound didn't change when I pulled the clutch in. The motor ran perfect otherwise and since I beat the s**t out of it on a daily basis, I figured I'd damaged something in the lower end, even with the excellent maintainence provided. I tore the motor apart expecting to find a loose rod or main bearing. I didn't find anything except that everything bearing related was just fine. So, what made the knock noise? It ended up that the alternator rotor was the culprit. The aluminum portion that holds the magnets had worked loose from the steel core. There was about .010 to .015" of play. Just enough to make a slight noise. Lesson learned. Check the easy stuff first before tear down. Ride safe, Steve