An odd Rattle...

Always seems to work this way, fix one thing and the very next day another issue rears its ugly head. So my '79 KZ400H1 started making a little extra racket out of the left cylinder today. This included some movement in the corresponding spark plug. I haven't had the chance to pull anything and look since I just now finished walking it home. Man I never noticed how many hills Florida has until I'm pushing 300+lbs of weight after a long day of work. Anyways, when running the engine feels sluggish like the clutch is slipping, and the rattle/vibration intensifies with higher RPMs. Eventually though the bike acts as though out of gas an slows to a stop, leaving me on the side of the highway cursing the morons who try to run me over (but they do that no matter how fast I'm moving.) The following changes were made prior to this problem rearing up today. 1) New Rectifier/Regulator. 2) New Handlebars. 3) Mirrors... (obviously the reason for this problem!!!) 4) New Ignition Points. I'm just hoping I didn't break a valve or something. Really don't have the money or time to do a tear-down of the engine.

do a compression check first
that will let you know what is happening

pull all plugs out and wide open throttle when doing test

if all is good i see you said clutch is feels like its slipping that would be next
but when clutch rises hell you know it

I was thinking it might be the clutch, but the noise is coming from the engine and there is noticeable movement on the plug. I hope the rod didn't break and the damn piston isn't smacking stuff inside.

Robwolf wrote: ... noticeable movement on the plug....

Is the plug broken, or loose, or stripped plug hole threads?

Good Fortune!

Ok, plug was loose, however its 10pm and I live in an apartment so I'm not going to fire it up, neighbors might kill me. I'll find out if that was the rattle problem in the morning, could this also cause the lack of power, rev limiting, dying... etc? I guess if the plug isn't grounding well? BTW it isn't broken, was just loose. I guess I forgot to tighten them down well after putting them in a few weeks ago. Almost forgot, there was another issue earlier on in the day. Right as I was heading out from work I noticed the extra noise and felt a bit of a power drain. When I stopped to check on it, I found my tach cable had come loose from its position on the front of the head. There was oil spray all over it an the area in front of it. I tightened it back down and topped off the oil on the way home to make sure this wasn't the cause of my problem.

Robwolf wrote: Ok, plug was loose....

Should not run the engine with a loose spark plug.

Good Fortune!

I'm guessing one reason would be, loss of compression through gaps in spark port causes engine to not function quite right. I'll find out in the morning if this solved the initial problem. To bad I broke the clutch cable (or maybe just pulled it out of its proper place) before I made it home, adding another piece to be fixed. Anyone know what size clutch cable I should use with the KZ400 (using clubman bars instead of the LTD ones), I've had too much slack on the cable since I got the bike and its been a constant battle between loose lever and sticky clutch.

Running the engine with a loose spark plug is likely to strip the threads in the plug hole and blow the plug out of the head.

Good Fortune!

Well that fixed the problem with the engine rattle. When the clutch works again I'll see if the lack of power also stemmed from this. You've got to love how easy it is to make everything stop working, but just as easily fix. Just wish it didn't always seem like something way worse than what is actually wrong.

You should get into the habit of using a torque wrench when working on your bike, especially on stuff like spark plugs. It's not good to under or over tighten them. Ed

on your clutch you have to adjust the screw on the side of push rod for some play (at trans cover)

this picture just only referance www.kz400.com/KZ440MaintainanceFrameset.html