Engine noise.

Ok, I'm sure this won't help much but here goes. My engine is making a noise from the top end somewhere. Maybe the cams, cam chain, valves heck I don't know. It's like a zzzzzzzzzzzzzzz and is constant. It's been going on for a while but lately my ears are really dialing in on it. It's not getting worse but now it annoys the S#$%#@ out of me.

It's a 76 KZ900 and the engine has about 35,000 miles on it. I really doubt that it has ever been rebuilt.

At some point I will get a 1075 kit, but I wanted to take a little more time on that and get all the cosmetics done first.

Anyway thanks for any suggestions.

Has the camshaft chain tension been adjusted?

Probably sometime in about 1976 before the bike hit the showroom. Haaaaaaaa

Oh well, my cam side caps are leaking a little oil. I guess I will order some new ones and a gasket and check that chain tension while I'm in there. Should I just get a new cam chain while I'm at it, or will that be a major PITA?

Austin...You might want to hold off on the cam chain Bud,and just get in there first and have a look-see.If You're going to replace ANYTHING...wait til You pull it apart,and I can guarantee that You'll end up with a list of parts that You'll want to replace,from the top end.
There's a lot of activity going on in the head,and if it IS all original,then You will want to do it right.Don't short-cut in that area,or You'll regret it.
That noise You're hearing could be a chain roller that's ready to let go(hopefully not).
Anyway...plan on spending some money in there,once You pull it apart...so worth it,Bud.

Hmmm, maybe it's time to bust this head out that's been collecting dust in my garage for a year or so. I think I bought it last year. Here's a picture of the parts that were included and a write up from the seller.




"all new S.S Over size Intake valves,new exhaust valves. new valve seals. shim under buckets, new high lift valve guides, .500 lift springs, shim under buckets with shims. chambers are polished. there was some port work done when I started on the head so I never had anything done to them. the head was decked .020. APE cam gears. There could be more its been a while since I looked at it. I have over $400 in parts and almost that in labor."

Post edited by: austin3119, at: 2007/05/15 02:24

Dang looks like your almost set headwise. I would go for the 1075 kit and a set of good cams. But then you will need carbs, cam chain, welded crank, undercut gears and on and on and on... My God where does it end? :woohoo:

Actually Don, I have these carbs also in a box in the garage that I rebuilt a while back. I think I can get away without the welded crank and undercut gears, so I probably just need the slugs, cams, cam chain and some gaskets and I may be almost there.

Post edited by: austin3119, at: 2007/05/15 11:45

Post edited by: austin3119, at: 2007/05/15 11:46

Wow -- this repair potential seems to have quickly escalated from a possible simple routine maintenance item (adjust cam chain tension) to consideration of rather extensive engine work.

Just checking back in to be sure the quick easy routine 2000 mile cam chain tensioner adjustment has been done and failed to quiet the noise. You know the drill, working underneath the carbs from the left side. Best done with warm engine. Kick the motor over a few times. Use the 17mm bolt under the points cover to turn the engine forward until the T mark on the advancer unit lines up with the fixed mark on the engine. Never go backward. If go past the T mark, just go around again. This position puts maximum slack on the back side of the cam chain.

Loosen the lock nut and bolt on the automatic tensioner unit. Internal spring automatically takes up the cam chain slack. Tighten the bolt and then tighten the lock nut. If it's chain noise, and this adjustment doesn't stop it, the chain guide rollers may be worn out and need replacing.

This adjustment does not require removing the valve cover or even seeing the cam chaim.

That said, sure won't hurt to have a look inside, and what better excuse to go forward with that fine looking new head and absolutely beautiful carbs.

Post edited by: Patton, at: 2007/05/15 12:24

Patton, thanks for the advice. I will give it a try. Be forewarned, I'll probably be back to ask for more advice on this after I screw it up.

Post edited by: austin3119, at: 2007/05/15 12:36

austin3119 wrote:

Ok, I'm sure this won't help much but here goes. My engine is making a noise from the top end somewhere. It's like a zzzzzzzzzzzzzzz and is constant. It's been going on for a while but lately my ears are really dialing in on it. It's not getting worse. . .

Austin. . .DO THIS FIRST, before you get set on all the engine stuff.

Take the bike out on a quiet two lane road and run it up to about 65 mph.

While cruising at that speed, pull the clutch, and shut off the motor.

LISTEN TO A SILENT ENGINE.

Maybe the noise is chassis related.

Be careful re-engaging the engine.

Patton wrote:

. . . Use the 17mm bolt under the points cover to turn the engine forward until the T mark on the advancer unit lines up with the fixed mark on the engine. Never go backward. If go past the T mark, just go around again. This position puts maximum slack on the back side of the cam chain . . .

I have a question.

On my 650, the proceedure is to roll the engine past the T mark on the 2-3 cylinder, to a point about 20 degrees past it, to where there is a place on the advancer that is designated at the chain adjustment point. Where did your information come from?

Maybe there is a difference I need to know about.