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KZ750E1 engine rattle

  • Thread starter Thread starter 11csive
  • Start date Start date
1

11csive

Guest
Hi everybody.

First of all, let me know if making a non-GS post is considered a no-go. I'm posting this on here since we seem to have a lot of people with almost unlimited knowledge when it comes to these older bikes.

I've acquired a Kawasaki KZ750E1, which I'm trying to bring back to life. What I've done so far is:

Carb cleaning.
Carb syncing.
Oil change.
Oil-filter change
Valve clearance adjustments.
Cam chain tensioner checked a while back - will try have a look at it again if anyone thinks it is the cam chain.

PO put cheap no-name pods on it, and a quite noisy aftermarket exhaust, both of which I'm planning to pull of when time comes.

My problem is that the engine makes a rattling noise when running, which I'm trying to diagnose. From what I've read, it could be the cam chain, primary chain or even perhaps the starter clutch?? It's been a while since I looked around the almighty internet for a solution, so excuse me if I remember incorrectly or I'm saying something else which sounds stupid.

I've recorded a short video, trying to catch the sound from the engine. It's a little bit tough because of the loud exhaust, but I did the best I could. I'm hoping that someone with better experience could come up with a more qualified guess than me.

 
My guess is cam chain noise. Does your cam chain tensioner have the cross wedge w/spring cap or does the bike use the earlier type? Either way, I'd verify the tensioner is doing what it should.

One thing many people don't understand is that the tensioner needs to be removed and/or loosened any time the valve cover is about to be installed. The valve cover has a rub block that depresses the cam chain so if you don't loosen the tensioner installing the cover results in an overly tight chain.
 
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If it is the cam chain tensioner, at idle it makes a slapping noise. Won't hurt to take the cam chain tesnsioner off and verify its working properly then refit it taking care to follow the correct install procedure. The Z650/750 engine has, as you say a primary chain. I don't know if that has a tensioner...? Also is it a chain drive to the starter or is it gears?
 
Nessism said:
My guess is cam chain noise. Does your cam chain tensioner have the cross wedge w/spring cap or does the bike use the earlier type? Either way, I'd verify the tensioner is doing what it should.

One thing many people don't understand is that the tensioner needs to be removed and/or loosened any time the valve cover is about to be installed. The valve cover has a rub block that depresses the cam chain so if you don't loosen the tensioner installing the cover results in an overly tight chain.
Click to expand...

When I get back to the bike tomorrow, I will check what tensioner type it has. And also doublecheck that it's in working condition.

That makes perfectly good sense, and honestly that's something I haven't thought of when doing the valves. It did sound like this prior to the removal of the valve cover though, but who knows, someone else might have made the same mistake as me. Would a cam chain being too tight be able to produce noises like the ones on my bike?
 
Jonathan said:
If it is the cam chain tensioner, at idle it makes a slapping noise. Won't hurt to take the cam chain tesnsioner off and verify its working properly then refit it taking care to follow the correct install procedure. The Z650/750 engine has, as you say a primary chain. I don't know if that has a tensioner...? Also is it a chain drive to the starter or is it gears?
Click to expand...

I'll have a look at the tensioner again. From what I know, the primary chain doesn't have a tensioner, but I'm not certain. I've had the bike for a while, but only now had the time to start looking at it, so I'm not really familiar with the engine yet.
 
An overly tight cam chain won't cause the noise, but if someone installed the valve cover before releasing the tensioner they may have over tensioned the cam chain and wound up breaking one of the tensioner shoes/guides.

The primary chain does not have a tensioner. The chain typically lasts the life of the engine though.

The starter clutch is located on what's called the secondary shaft. The secondary shaft is driven by the primary chain, and then a gear between the secondary shaft and the clutch transfers power to the transmission.
 
Nessism said:
An overly tight cam chain won't cause the noise, but if someone installed the valve cover before releasing the tensioner they may have over tensioned the cam chain and wound up breaking one of the tensioner shoes/guides.

The primary chain does not have a tensioner. The chain typically lasts the life of the engine though.

The starter clutch is located on what's called the secondary shaft. The secondary shaft is driven by the primary chain, and then a gear between the secondary shaft and the clutch transfers power to the transmission.
Click to expand...

I see. Will have a look at both the tensioner and the chain guides.
 
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Went to have a look at the bike today. I have the manual cam chain tensioner. So theoretically it shouldn't be subject to the over tightened cam chain, correct? It's locked into place so it doesn't pick up the slack created by removing the valve cover?

Anyway, removed the tensioner and inspected it, it seems to work as it should. Reinstalled it per the factory service manual and I could hear it "pop" into place. Is it possible that it's still the tensioner being at fault? Could the spring be too weak to keep the chain as tight as it should? Or what would you suggest to do from here on?

Thanks a lot for the help :)
 
If the tensioner springs out like it should then the issue is likely something else.
 
And does the noise sound any different? It is difficult to diagnose a possible fault by third party descriptions of a noise...
 
Jonathan said:
And does the noise sound any different? It is difficult to diagnose a possible fault by third party descriptions of a noise...
Click to expand...

Noise seems to be exactly the same, so as it sounds in the video :)
 
on the video, the sound seems to be louder on the rh side of the bike.
Could it be behind the clutch cover ?

Have you tried to locate the sound by using a large screwdriver, one end
to the ear, the other end to different places on the engine ?
 
Rijko said:
on the video, the sound seems to be louder on the rh side of the bike.
Could it be behind the clutch cover ?

Have you tried to locate the sound by using a large screwdriver, one end
to the ear, the other end to different places on the engine ?
Click to expand...

Haven't tried locating it with the method you mention. I did however try running the engine with the oil cap off, which didn't enhance the noise. So I'm thinking not the clutch? :)
 
11csive said:
Haven't tried locating it with the method you mention. I did however try running the engine with the oil cap off, which didn't enhance the noise. So I'm thinking not the clutch? :)
Click to expand...

agreed, probably not the clutch then
 
just remembered, a friend once put synthetic oil in and the cams were making noise after that.
Switching back to 10W40 mineral solved it.

You did use mineral oil, right ?
 
Rijko said:
just remembered, a friend once put synthetic oil in and the cams were making noise after that.
Switching back to 10W40 mineral solved it.

You did use mineral oil, right ?
Click to expand...

It's running semi-synthetic as far as I remember. 10W40. Could that really be making this? Was the noise similar to this?
 
the sound was a bit louder actually, but that was on a GS without cam guides directly in the aluminium head.
I think the KZ has metal half-moon cam guides (not sure, i am not familiar with this Kawa) so the sound may be different.
 
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try the large screwdriver 'stethoscope', it amplifies sound big time.
At least you can usually tell where the sound is coming from.
 
Rijko said:
the sound was a bit louder actually, but that was on a GS without cam guides directly in the aluminium head.
I think the KZ has metal half-moon cam guides (not sure, i am not familiar with this Kawa) so the sound may be different.
Click to expand...

Okay. This is completely new to me. Had no idea the type of oil would be able to produce problems like this. I'll probably try to locate the sound and if it's coming from the cams, maybe I should try to change the oil then.
 
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