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KZ750E1 engine rattle

  • Thread starter Thread starter 11csive
  • Start date Start date
do you have a workshop manual ?

For GS bikes there's a section that describes measuring the length of 20 cam chain links to determine cam chain wear.
 
Rijko said:
do you have a workshop manual ?

For GS bikes there's a section that describes measuring the length of 20 cam chain links to determine cam chain wear.
Click to expand...

I do. Thought about measuring that, but then I noticed that the tensioner doesn't seem to be bottoming out at all, which made me doubt that it's worn too bad. But maybe I should do it anyway to exclude that as a possibility.
 
The type of oil used has nothing to do with that noise.

This engine doesn't use cam bearing inserts. The cam rides directly on the aluminum cam journals machined into the head.

When you checked the valve clearances did you remove the cams and change shims? If so, maybe a couple of the cam caps came loose now. I'd pull the valve cover and look inside for something obvious.
 
Nessism said:
The type of oil used has nothing to do with that noise.

This engine doesn't use cam bearing inserts. The cam rides directly on the aluminum cam journals machined into the head.

When you checked the valve clearances did you remove the cams and change shims? If so, maybe a couple of the cam caps came loose now. I'd pull the valve cover and look inside for something obvious.
Click to expand...

Yes I adjusted the valve clearances, almost all of them were out of spec. Also a couple of the cam cap threads were ruined, so I had to fix them as well. I'm pretty sure I did so properly, and I got them all torqued to spec. Used heli-coils to preserve the bolt size and prevent having to drill the caps and drilling "too large" in the cylinder head.

The engine sounded the same before this though, and I didn't notice any obvious damage back then. But I will definitely pull the valve cover again, and maybe also the cam shafts to inspect them properly. Anything in particular to look for besides loose cam caps?
 
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Had the time to have another look at the bike today. Pulled the valve cover and inspected the cam caps. None of them were loose. Torqued to spec and seated properly. However, I decided to pull the camshafts and try to have a look at the cam chain guides. I'm unsure of how these are "allowed" to look when used, but to me they seem worn down? Aren't they supposed to be covered with black nylon or whatever material it is, like the one in the valve cover? If so, I imagine them being the reason for the rattle/slapping noise.

9zazx1h.jpg



Ai6wRPw.jpg


The one with a little black left is the rear one/the one that the chain tensioner applies pressure on.
 
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Yes, they're worn - but if the tensioner is working that of itself wouldn't make noise.Seen worse...
I can't see the vid but I'll ask - does the noise go away with some revs ?

The 550/650/750 family of engines use rubber inserts in the clutch cush drive. These collapse with use.
Typically if the noise disappears with revs, that's the problem.
I have no idea if the rubbers are available. For a couple of race engines I've made up urethane inserts with good results. I'm told that making up tubular pieces to go around the inserts which are then press fitted into the backplate also works. For a while anyway...
 
Comparing those tensioner guides to some on ebay they look the same. I don't think those are the problem.
 
Finally had the time to look at the bike again today. I've checked the chain wear which is fine. Just about 128mm on the 3 readings I made, the service limit being 128.9mm. I have a workshop stethoscope laying around somewhere, so I'll try and put the bike back together and try to pinpoint the sound some more. I'll also try and be more aware of if it disappears with rev.

If anyone have other suggestions, please let me know. And thank you to everyone for spending time helping me out.
 
11csive said:
I have the manual cam chain tensioner.
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?
Thanks a lot for the help :)
Click to expand...

This doesn't sound like a manual aftermarket cam chain tensioner if it has springs on the side and it popped into place.
I just got APE manual tensioner in the mail last night, plan to install this morning, my bike is making a similar noise that just started occuring recently.
 
Carter Turk said:
This doesn't sound like a manual aftermarket cam chain tensioner if it has springs on the side and it popped into place.
I just got APE manual tensioner in the mail last night, plan to install this morning, my bike is making a similar noise that just started occuring recently.
Click to expand...

It's not an aftermarket one. The early ones shipped with a stock manual tensioner. There's no spring on the side, the spring I meant is the one pushing the rod onto the cam chain guide :)
 
If the can chain and tensioner are good then its the primary chain that drives the clutch hub. If The sound lessens as you bring the revs up to around 2000 ..but doesnt completely go away..its the primary chain. Just replaced the on in my 77 KZ65B1 not too long ago and no more noise. Had to split the cases to do it though. As Ed said, the primary "should" last the life of the bike but not if it has been raced and beat to death like most KZs were in the day.
 
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